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Evaluation of Solid Fuel Char Briquettes from Human Waste
Abstract
The developing world faces dual crises of escalating energy demand and lack of urban sanitation infrastructure that pose significant burdens on the environment. This paper presents results of a study evaluating the feasibility of using human feces-derived char as a solid fuel for heating and cooking, and a potential way to address both crises. The study determined the energy content and the elemental composition of chars pyrolyzed at 300, 450, and 750°C. Fecal chars made at 300°C were found to be similar in energy content to wood chars and bituminous coal, having a heating value of 25.6 ± 0.08 MJ/kg, while fecal chars made at 750°C had an energy content of 13.8 ± 0.48 MJ/kg. The higher heating values of the studied chars were evaluated using their elemental composition and a published predictive model; results found good agreement between the measured and predicted values. Fecal chars made at low temperatures were briquetted with molasses/lime and starch binders. Briquettes made with 10% starch had an average impact resistance index of 79 and a higher heating value of 25 MJ/kg. These values are comparable to those of commercial charcoal briquettes, making fecal char briquettes a potential substitute that also contributes to the preservation of the environment.
... However, there exists a compelling opportunity to advance beyond these conventional practices or be replaced by an improved version of fuel generated from solidified fecal sludge. Nevertheless, the energy efficiency of dried FS only is suboptimal due to the low calorific value of the fuel content, though fecal sludge charcoals are often proven to serve high energy efficiency (Sagor et al., 2022;Ward et al., 2014). ...
... Fecal sludge valorization offers a promising pathway for recovering energy and nutrients from waste, while simultaneously mitigating the financial burdens associated with treatment processes and alleviating the environmental and health impacts. Various methods for obtaining biofuel products from sewage raw materials are extensively being researched (Otieno et al., 2022;Sagor et al., 2022;Ward et al., 2014;Xu et al., 2023;Yahav et al., 2023). Various studies have explored the utilization of different waste materials, such as fecal sludge, pineapple peels, food waste and sewage sludge, to produce biochar-briquettes (charred or non-charred) for cooking and heating purposes (Ariani et al., 2023;Kizito et al., 2022;Atwijukye et al., 2018;Sagor et al., 2022;Ward et al., 2014;Xu et al., 2023). ...
... Various methods for obtaining biofuel products from sewage raw materials are extensively being researched (Otieno et al., 2022;Sagor et al., 2022;Ward et al., 2014;Xu et al., 2023;Yahav et al., 2023). Various studies have explored the utilization of different waste materials, such as fecal sludge, pineapple peels, food waste and sewage sludge, to produce biochar-briquettes (charred or non-charred) for cooking and heating purposes (Ariani et al., 2023;Kizito et al., 2022;Atwijukye et al., 2018;Sagor et al., 2022;Ward et al., 2014;Xu et al., 2023). Biochar, a type of charcoallike substance, produced through the process of controlled pyrolysis of organic biomass in a low-oxygen environment, has been widely acknowledged as a more environmentally friendly fuel alternative when compared with conventional biomass fuels (Kim and Parker, 2008;Sagor et al., 2022;Ward et al., 2014). ...
Developing countries are facing challenges due to rapid urbanization and insufficient sanitation facilities. However, valorizing treated fecal sludge as a fuel source presents an opportunity to recover energy and mitigate environmental impacts. This experimental study aimed to produce low-cost biofuel from dried fecal sludge and enhance its energy efficiency by incorporating locally available organic matters. Various organic materials like rice husk, cow dung, sawdust, and coal were carbonized and mixed with the sludge to enhance calorific value. Eight sludge and organic matter mixtures were formed into briquettes. The blend of 50% sludge and 50% coal yielded the highest calorific value of 14618 KJ/kg and a boiling time of 14 minutes. The second-highest result was for 50% sludge and 50% cow dung, with a calorific value of 14427 KJ/kg and a boiling time of 23 minutes. The study found that blending sludge with organic materials enhances energy output. Briquettes with 50% sludge and 50% coal cost 19.87 BDT/kg, while those with 50% sludge and 50% cow dung cost 14.37 BDT/kg, proving more economical. The latter blend emerged as the most efficient and cost-effective biofuel, offering a sustainable eco-friendly solution for Bangladesh’s rural energy market.
... FS can be safely subjected to pyrolysis at a certain temperature to convert it into solid fuel. Production of charcoal by the pyrolysis process from various animal manures, including human faeces, has been investigated by many researchers (Abnisa et al., 2013;Cantrell et al., 2012;Sahoo et al., 2021;Ward et al., 2014). Charcoal produced through pyrolysis of various animals and plant wastes can further be transformed into briquettes that may have heating values from 12 to 25 MJ/kg of fuel (Ward et al., 2014). ...
... Production of charcoal by the pyrolysis process from various animal manures, including human faeces, has been investigated by many researchers (Abnisa et al., 2013;Cantrell et al., 2012;Sahoo et al., 2021;Ward et al., 2014). Charcoal produced through pyrolysis of various animals and plant wastes can further be transformed into briquettes that may have heating values from 12 to 25 MJ/kg of fuel (Ward et al., 2014). Several research studies have been conducted on the prediction and evaluation of briquettes from charcoal. ...
... Several research studies have been conducted on the prediction and evaluation of briquettes from charcoal. Ward et al. (2014) evaluated the char briquettes processed from human waste char with different binding materials such as rice starch, molasses and lime. A range of cost-effective binders with coal was tested by Taulbee et al. (2009). ...
Briquetting technology is one of the useful methods for sustainable management of Fecal sludge (FS). This study aims to evaluate the physical and thermal properties of briquettes made of FS charcoal with different binding materials. FS charcoal was produced by pyrolysis of the dry FS at 400 ⁰ C and subsequently was briquetted with rice starch and different ratio of rice husk powder (RH), corncob powder (CP), wheat powder (WP), and cow dung (CD). The ratios of FS charcoal and binding materials were chosen as 80: 20, 75:25, and 70:30 for RH, CP, and WP briquettes. For CD briquettes, the ratios were 70:30, 50:50, and 30:70. Each briquette was characterized in terms of bulk density, moisture content, compressive strength, energy content, and proximate analysis. The bulk density and the compressive strength of all briquettes were in the range of 1990–2150 kg/m ⁰ and 172–815 KPa, respectively. The moisture contents of all briquette samples achieved 5% to 8% that met DIN 51731standards. The ash content in briquettes was comparatively higher, achieving 29–46%. The energy contents of all briquette samples were above 12.0 MJ/kg indicating sustainability for combustion. The briquettes made of FS charcoal and CD were found suitable having a lower cost (0.18–0.28 US$/kg), sufficient compressive strength (>375 KPa), and desirable energy content (>13.40 MJ/kg). The produced FS briquette can be used for cooking and heating. The FS charcoal briquettes showed a potential alternative to manage human waste for sustainable environmental protection.
... time, and heating rate. Ward et al. [75] pyrolyzed dried human feces in a pyrolysis furnace at 300 ∘ C, 450 ∘ C and 750 ∘ C for 2 h, with the main purpose of producing char. The heating rates were up to 13.9 K/min. ...
... Bittencourt and Martins [69] discussed that volatile organic compounds might be responsible for heterogeneous and/or homogeneous reactions leading to exothermicity. In a similar conclusion, Ward et al. [75] indicated that the decrease in char energy content with the temperature increase is likely due to the degradation and volatilization of high-energy hydrocarbons. These two works point in the same direction, i.e., the onset of exothermicity is probably associated with the release of volatile compounds starting at around 300 ∘ C for feces and 200 ∘ C for fecal sludge. ...
... The design proposed by the University of Colorado Boulder called the "Sol-char toilet" uses pyrolysis as the driving mechanism to disinfect feces [75,101]. The concentrated solar power transforms the fresh feces deposited in the specific chambers (for collection and reaction) into char, which can be used as fuel and soil amendment. ...
Defecating in precarious facilities or even in the open environment is an undeniable reality in low-income countries. A thermochemically-driven treatment unit (TDTU) can be a fast, viable, and efficient solution to mitigate the impacts of fecal matter on the surrounding environment, using the energy potential of feces to transform them into solid and gaseous products without pathogens. Here, we review the data from papers dealing with the characterization of fecal matter and thermochemical treatments of fresh human feces and fecal sludge to link the thermochemical conversion of fecal matter with the development of TDTUs. This review aids researchers and guides policymakers by making explicit for the first time how the fate of human feces in low-income countries affects the development of thermochemical units and the choice of treatment routes. The implication of choosing TDTUs to operate as offsite centralized units is dealing with a residue with more water, less fixed carbon, less energetic value, and more inorganic content. On the contrary, onsite TDTUs must convert a fresh residue with almost 80 wt% water content, which has been achieved using out-of-bed combustion and solar power. The inorganic solid products left in TDTUs are safe-manageable and valuable in environment-friendly applications, such as soil amendments and carbon sequestration. Overall, this review suggests that TDTUs have great potential to replace filthy pit latrines and end open defecation, decreasing social inequalities and the marginalization of the most vulnerable in humble communities. Nevertheless, a research gap exists in developing TDTUs to treat the fe-cal matter onsite.
... Pyrolysis of human faeces at temperatures > 300 o C can lead to: (i) complete elimination of pathogens (Atwijukye et al., 2018), and (ii) minimized oxygen containing functional groups, while also increasing the aromatic carbon content, which in turn lessens the emission of CO2 and smoke (He et al., 2018). However, this process also lowers the calorific values of human faeces due to the degradation of energy rich aliphatic hydrocarbons with increasing pyrolysis temperature (Ward et al., 2014). Despite the degradation in energy content, the gross calorific values of human faeces pyrolyzed between 300 o C and 450 o C are within 18 -26 MJ/kg (Ward et al., 2014), a range comparable to 19 -25 MJ/kg of wood fuel (Ruiz-Aquino et al., 2019). ...
... However, this process also lowers the calorific values of human faeces due to the degradation of energy rich aliphatic hydrocarbons with increasing pyrolysis temperature (Ward et al., 2014). Despite the degradation in energy content, the gross calorific values of human faeces pyrolyzed between 300 o C and 450 o C are within 18 -26 MJ/kg (Ward et al., 2014), a range comparable to 19 -25 MJ/kg of wood fuel (Ruiz-Aquino et al., 2019). Hence, blending of pyrolyzed human faeces hereon referred to as faecal char, with other waste streams such as sawdust is recommended to improve the calorific values of the briquettes produced (Atwijukye et al., 2018). ...
... Additionally, carbonized sawdust hereon referred to as sawdust char, could be a suitable material to blend with faecal char to improve their calorific values. Studies involving production of briquettes by densification of faecal char and sawdust char mixed with starch or molasses binders to form durable solids for domestic heating and J o u r n a l P r e -p r o o f cooking have been reported (Kabok et al., 2018;Atwijukye et al., 2018;Ward et al., 2014). These studies have explored on the influence of organic binder types (molasses and starch), binder ratios, densification pressures, and carbonization temperatures on the combustion behaviours and heating values of the briquettes. ...
Over reliance on charcoal has accelerated deforestation in sub-Saharan Africa. Seeking alternative sustainable and environmentally friendly sources of biomass energy to meet the escalating energy demand is therefore vital. However, limited evidence exists on the concentrations of toxic emissions of different biomass fuels. Herein, dried human faeces and sawdust were pyrolyzed at 350 °C to produce biochar and mixed in equal ratio to produce briquettes through densification, with molasses (10 wt.%) used as a binder. A comparative study on the heating properties and emission level of carbon monoxide (CO), nitric oxide (NO), and hydrogen sulphide (H2S) during combustion of charcoal, and co-combustion (50:50 wt. %) of charcoal with briquettes was conducted. The thermal profile of the flue gases indicated rapid combustion of volatile gases followed by slow oxidation of the char. Co-combustion significantly (P < 0.05) enhanced the amount of heat energy released with flue gases temperatures reaching a peak of 475 °C. The briquettes had a gross calorific value of 19.8 MJ/kg which was lower than 25.7 MJ/kg for charcoal. Combustion of charcoal did not emit NO, however the concentration of CO was above the critical short term limits of 35 ppm. The concentration of CO and H2S was above the short term exposure limits of 35 ppm, and 0.005 ppm, respectively, during co-combustion, whereas NO concentration was below dangerous exposure levels of 100 ppm. These results suggest that co-combustion of charcoal with the briquettes is a promising approach to generate safe and sufficient heat energy for cooking and reduce deforestation.
... A few studies that have investigated the thermochemical conversion of human faeces have focused on the development of energy conversion systems and operating conditions (Onabanjo et al., 2016a;Ward et al., 2014;Jurado et al., 2018;Gold et al., 2018) with limited understanding of fuel conversion processes and interaction. From studies completed, there is the understanding that temperature and residence time are factors affecting the yield and quality of products (Ward et al., 2014;Liu et al., 2014;Gold et al., 2018). ...
... A few studies that have investigated the thermochemical conversion of human faeces have focused on the development of energy conversion systems and operating conditions (Onabanjo et al., 2016a;Ward et al., 2014;Jurado et al., 2018;Gold et al., 2018) with limited understanding of fuel conversion processes and interaction. From studies completed, there is the understanding that temperature and residence time are factors affecting the yield and quality of products (Ward et al., 2014;Liu et al., 2014;Gold et al., 2018). Operating temperature of 300 • C is suggested to be suitable for fuel production but those above 600 • C were not recommended for faecal char. ...
... Studies by Liu et al. (2014), Ward et al. (2014) and Gold et al. (2018) have showed that pyrolysis temperature of 300 • C can affect the quality of faecal char as fuel, due to progressive loss of energy-rich hydrocarbons and an increasing amount of ash. Unlike coal fuels, where low pyrolysis temperature improves HHVs via decarboxylation, aromatization, condensation and polymerization, low heat can cause thermal degradation of biomass feedstocks. ...
Human faeces (HF) are treated as wastes in many parts of the world, a resource that can be converted to energy and fuels. To enhance the understanding of fuel conversion processes and decomposition characteristics, this study investigated the pyrolysis behaviour and evolved gas profiles of HF using thermogravimetry with gas chromatography–mass spectrometry methods. Kinetic parameters were deduced using model-free kinetic models. Results are compared with simulant faeces (SF), wood biomass (WB) and HF–WB blends. The pyrolysis of HF involved two decomposition peaks — a fronting peak with weight loss of ∼51 wt% and a tailing shoulder peak with weight loss of ∼15 wt%. The apparent activation energy for HF varied from 122–382 kJ/mol at conversion rates of 10%–90% using Kissinger–Akahira–Sunose model. Some of the key pyrolysis products for HF at 370 °C were 4-methoxy-phenol, n-hexadecanoic acid, phenol, 4-methyl- and indole isomer (pyrrolo[1,2-a]pyridine). At 530 °C, evolved gases were largely fragmented with high proportions of alkanes and alkenes including 3-dodecane, 2-undecane, 6-tridecene, 2-propenylidene-cyclobutene. These products differed to WB that are largely hydroxyphenyls and methoxyphenols with guaiacyl or syringil structures. Blending with WB improved pyrolysis of HF, irrespective of the proportions of blend.
... However, there is a lack of research on the use of excreta from dry toilets as pyrolysis substrate. Previous studies have included human faeces [14], and faecal sludge from pit latrines [15] and septic tanks [16], which have different characteristics from dry toilets with excreta and wood chips [7]. This also concerns the environmental safety and the effect of soil biochar addition on the growth of plants and consumption of resulting produce by animals and humans. ...
... Higher temperatures and higher heating rates usually cause more compounds to volatilize, leading to a lower yield [39]. The yield in this study was comparable to biochar yields with human feces produced at 450 °C and 750 °C (29 and 30% DM [14]). Biochar production from fecal sludge at 500 °C, 600 °C and 700 °C also had comparable yields of 35, 31 and 31% DM [16]. ...
... In comparison, biochars from woody feedstocks have typically lower concentrations of macronutrients (i.e., N, P, and K), their positive effect on soil fertility is attributed rather to effects like increasing cation exchange capacity, nutrient retention, water holding capacity, and elevation of soil pH [55]. This N concentration in the DTS-biochar was lower than reported for biochar derived from human feces (48 g N/kg DM [14]), but was comparable to fecal sludge derived biochars (24-29 g N/kg DM [16]) and wastewater sludge biochars (9-19 g N/kg DM [56]). These reported biochars were all produced at similar pyrolysis temperatures (450-700 °C) to the one used in this study. ...
Biochar is increasingly being applied as a soil amendment in agriculture. Biochar is typically produced from plant biomass and contains relatively low amounts of plant nutrients (e.g., N, P, and K), thus providing limited fertilizer value. Human excreta contains plant nutrients that could be recycled to create sustainable agricultural nutrient cycles. This study investigated the potential of biochar derived from a dry toilet substrate as soil amendment. The substrate consisted of urine, faeces, and wood chips, and was pyrolyzed at 500–650 °C for 10 min. The biochar was analyzed for plant available P, water leachable P and K, carbon stability, pH, electrical conductivity, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dioxins, and germination tests with barley and lettuce were conducted to estimate the biochar fertilizer value and potential bio-toxicity. The biochar contained 25.0 ± 1.0 g N/kg dry mass (DM), 33.1 ± 2.1 g P/kg DM and 20.7 ± 0.2 g K/kg DM. 65% DM P was extractable by formic acid solution, 31.7% DM P and 60.5% DM K were water leachable in a ten-day column water-leaching experiment. The biochar complied with European regulations for PAHs, PCBs, dioxins and heavy metal concentrations, except for Zn and Ni. Germination of salt-resistant barley was not affected by biochar doses < 50% DM, while salt-sensitive lettuce germination was inhibited at doses ≥ 2% DM, indicating that the dry toilet substrate biochar induced salt stress. Based on these results, it is recommended that urine separation should be considered for biochar of excreta, which could reduce salt stress while maintaining concentrations of “fixed” or bioavailable nitrogen.
Graphic Abstract
... Đối với vấn đề xử lí phân bùn bể tự hoại, chúng tôi đề xuất giải pháp thu gom bùn bể tự hoại. Sau đó sản xuất than đốt từ phân bùn không gây ô nhiễm theo nghiên cứu của Ward (2014). Như vậy, gene kháng thuốc sẽ bị loại bỏ trong quá trình đốt và không lan truyền ra môi trường. ...
... Như vậy, gene kháng thuốc sẽ bị loại bỏ trong quá trình đốt và không lan truyền ra môi trường. Than đốt cũng là nguồn lợi kinh tế khi mà nguồn than đốt đang dần cạn kiệt [16]. ...
Nghiên cứu này nhằm mục tiêu khảo sát sự tồn tại của 12 ARGs kháng lại 9 loại kháng sinh trong bùn bể tự hoại tại 2 thành phố lớn là Hà Nội và thành phố Hồ Chí Minh. Trong nghiên cứu này, chúng tôi thu thập 26 mẫu bùn phân ở Hà Nội và 24 mẫu ở thành phố Hồ Chí Minh. Sự hiện diện của các ARG đã được kiểm tra theo hai hướng: (1) tách chiết DNA trực tiếp từ các mẫu bùn, sau đó tiến hành PCR khảo sát sự hiện diện của ARGs; (2) phân lập E. coli từ mẫu bùn, tách chiết DNA E. coli để khảo sát sự hiện diện của ARGs. Kết quả xác định gene kháng thuốc trên E. coli tại Hà Nội và Tp.HCM tương ứng là 0 và 44% kháng Streptomycin; 50% và 40% kháng Sulfonamide; 0 và 4% kháng Erythromycin; 0 và 65% kháng Chloramphenicol; 100% và 98% kháng Tetracycline; 50% và 16% kháng Trimethoprim; 100% và 30% kháng β-Lactams; 0 và 0 kháng Gentamycin; không có gene kháng Quinolone.
... Đối với vấn đề xử lí phân bùn bể tự hoại, chúng tôi đề xuất giải pháp thu gom bùn bể tự hoại. Sau đó sản xuất than đốt từ phân bùn không gây ô nhiễm theo nghiên cứu của Ward (2014). Như vậy, gene kháng thuốc sẽ bị loại bỏ trong quá trình đốt và không lan truyền ra môi trường. ...
... Như vậy, gene kháng thuốc sẽ bị loại bỏ trong quá trình đốt và không lan truyền ra môi trường. Than đốt cũng là nguồn lợi kinh tế khi mà nguồn than đốt đang dần cạn kiệt [16]. ...
Nghiên cứu này nhằm mục tiêu khảo sát sự tồn tại của 12 ARGs kháng lại 9 loại kháng sinh trong bùn bể tự hoại tại 2 thành phố lớn là Hà Nội và thành phố Hồ Chí Minh. Trong nghiên cứu này, chúng tôi thu thập 26 mẫu bùn phân ở Hà Nội và 24 mẫu ở thành phố Hồ Chí Minh. Sự hiện diện của các ARG đã được kiểm tra theo hai hướng: (1) tách chiết DNA trực tiếp từ các mẫu bùn, sau đó tiến hành PCR khảo sát sự hiện diện của ARGs; (2) phân lập E. coli từ mẫu bùn, tách chiết DNA E. coli để khảo sát sự hiện diện của ARGs. Kết quả xác định gene kháng thuốc trên E. coli tại Hà Nội và Tp.HCM tương ứng là 0 và 44% kháng Streptomycin; 50% và 40% kháng Sulfonamide; 0 và 4% kháng Erythromycin; 0 và 65% kháng Chloramphenicol; 100% và 98% kháng Tetracycline; 50% và 16% kháng Trimethoprim; 100% và 30% kháng β-Lactams; 0 và 0 kháng Gentamycin; không có gene kháng Quinolone.
... Coal can be blended with a small quantity of this agricultural waste (agro residues) to produce briquettes (bio-coal briquettes) which ignites fast, burn efficiently, producing little or no smoke and cheaper than coal briquettes (Ward et al., 2014) [17] . Thus, the studies is aimed at formulating eco-friendly biocoal briquette from agro-waste and study how the binders affects the calorific values of the briquette through water boiling test. ...
... Coal can be blended with a small quantity of this agricultural waste (agro residues) to produce briquettes (bio-coal briquettes) which ignites fast, burn efficiently, producing little or no smoke and cheaper than coal briquettes (Ward et al., 2014) [17] . Thus, the studies is aimed at formulating eco-friendly biocoal briquette from agro-waste and study how the binders affects the calorific values of the briquette through water boiling test. ...
The potential use of biomass as energy source in Nigeria is very high and this can be explained from the fact that about 80 % of Nigerians are rural or semi-urban dwellers that depend solely on biomass for their energy source. This research investigates the formulation of bio-coal briquette from groundnut shell, maize cob and rice husk and also studies how incorporation of binder affects the calorific values of the formulated briquettes. Some briquettes were formulated from the agro-waste with the incorporation of equal amounts of starch and coal (samples B, E and H) while in other briquettes, only starch was incorporated (samples A, D and G). Briquette samples C, F and I were formulated without any binder. The result also showed that the briquette samples (with or without binder) has higher burning rate and heating values than firewood. The results showed that all the briquette samples incorporated with starch or starch and coal binders boiled water at 16 min while firewood and briquette samples without binder boiled at 20 min except for maize cob briquette that could not boil water at 20 min. Incorporation of binders was found to increase the calorific values the briquette significantly. It was observed that incorporation of coal as binder had a significant effect only on the calorific value groundnut shell briquette samples. The result showed that briquettes will serve as a more effective substitute for firewood as it shows more combustion characteristics over firewood and the raw materials (agro-waste) are readily available. Introduction Biomass, particularly agriculture residues seem to be the most promising energy resources for developing countries (Patomsok, 2008) [13]. Rural households and minority of urban dwellers depend solely on fuel woods (charcoal, firewood and sawdust) as their primary source of energy for the past decades (Onuegbu et al., 2010) [8]. Of all the available energy resources in Nigeria, coal and coal derivatives such as smokeless coal briquettes, bio-coal briquettes and biomass briquettes have been shown to have the highest potential for the use as suitable alternative to coal/fuel wood in industrial boiler and brick kiln for thermal application and domestic purposes. Global warming has become an international concern. Global warming is caused by greenhouse gasses which carbon dioxide is among the major contributors. It was shown that increase emissions of CO 2 have been drastically reduced owing to the fact that the rate of deforestation is higher than a forestation effort in the country (Yahaya and Ibrahim, 2012) [18]. In counties like Japan, China, India etc., it was observed that agricultural wastes (agro residues) can be briquetted and used as substitute for wood fuel. Every year, millions of tons of agricultural waste are generated (Wang et al., 2017) [16]. These are either not used or burnt inefficiently in their loose form causing air to the environment. The major residues are rice husk, corn cob, coconut shell, jute stick, groundnut shell, cotton stalk, etc. these wastes provide energy by converting into high density fuel briquettes. These briquettes are very cheap, even cheaper than coal briquettes. Adoption of briquettes technology will not only create a safe and hygienic way of disposing the waste, but turn into a cash rich venture by converting waste into energy and also contributing towards a better environment (Zubairu and Gana, 2014) [19] .
... Though at this HHT, the yield and energy content of the char reduce to half [67]. Ward et al. (2014) observed the faecal chars made at 750 • C having 13.8 ± 0.48 MJ/kg, which was much lower than those made at 350 • C with 25.6 ± 0.08 MJ/kg [70]. ...
... Though at this HHT, the yield and energy content of the char reduce to half [67]. Ward et al. (2014) observed the faecal chars made at 750 • C having 13.8 ± 0.48 MJ/kg, which was much lower than those made at 350 • C with 25.6 ± 0.08 MJ/kg [70]. ...
The utilisation of micro-scale thermal treatment technologies for non-sewered applications has been emerging as a prominent route for the safe treatment and disposal of high water content hazardous feedstock. This study provides a comprehensive review of the technological concepts practiced up to date in commercial/pilot and small scales for various types of solid fuels. The respective challenges are critically described and discussed to aid in the selection of promising technology for on-site sanitary applications. Furthermore, the challenges observed with the nominated (pyrolysis) technology are discussed in detail and addressed. This study suggests rapid energy recovery from by-products primarily made up of the highest yield of syngas with a desirable calorific value. The optimum operating ranges are discussed to ensure a reliable thermal conversion of sludge materials considering the application constraints and technology drawbacks. However, further studies are needed to investigate the uncertainties regarding emissions, energy consumption and overall associated costs.
... Sugarcane bagasse 28.32 [22] Orange bagasse 26.47 [19] Human waste 25.1 [27] Groundnut shells 22.50 [28] Waste plastic and coal 19.27 [15] Rice husk 17.04 [29] Rice straw and rice husk ash 17.01 [29] Paper and saw dust 16.68 [30] Waste oil 14.65 [31] Leather cassava tubers and sludge 7.68 [16] Used COVID-19 polypropylene isolation gown waste -Current work ...
... This is due to the absence of exothermic or endothermic peaks. These results are supported by previous works [15,21,27]. ...
Slow pyrolysis using a batch reactor at 450 °C was applied to the polypropylene (PP) powder derived from Coronavirus Disease 2019 (COVID-19) isolation gown waste to yield char briquettes, using sugar palm starch (SPS) and a manual hydraulic press. These studies are significant because of reductions in plastic waste from the preparation of barbecue coal due to environmental sustainability. The results presented here include the physical, morphological, thermal, combustion, and mechanical properties of char when reinforced with various percentages of SPS loadings (0, 10, 20, 30, and 40%), which act as a matrix/binder to produce char/sugar palm starch (C/SPS) composites. The physical and morphological characteristics of C/SPS composites were determined using Fourier transform infrared (FTIR) and field emission scanning electron microscopy (FESEM). On the other hand, the thermal and combustion properties of the C/SPS briquettes were studied via thermogravimetric and bomb calorimeter analysis. The results show that the compressive strength of the briquettes increased as the SPS loading increased, whereas the higher heating values (HHV) reduced. The findings indicate that C-80/SPS-20 briquettes presented excellent combustion characteristics (1,761,430 J/g) with satisfactory mechanical strength (1.463 MPa) in the compression test. Thus, C-80/SPS-20 briquettes are the most suitable composites for domestic and commercial uses.
... The efficient utilization of energy will be an urgent problem in the next several decades, and many people in developing countries lack an adequate supply of energy resources [1]. Therefore, it is imperative to find out alternative and clean fuels. ...
... In addition, molasses based carbonized seaweed pellets have improved durability [34]. Molasses was also used in human feces char, with calorific values of 12.92 ± 0.11 MJ/kg [1]. ...
In this study, the effect of four organic binders (protein, starch, lignin, and molasses) on woody biomass pellets was investigated. Properties of binder based pellets were evaluated for energy consumption, tensile strength, equilibrium moisture content, and combustion performance. Results indicate that the energy consumption of all binder based pellets was less than that of hydrochar pellets (45.38 J/g). In addition, starch and protein pellets exhibited better mechanical strength when binder content is 20% (3.07 and 3.40 MPa, respectively). Scanning electron microscope results indicate that starch and protein combined closely with hydrochar. Pellets with starch as the binder (20%) exhibited the highest equilibrium moisture content. Regarding combustion performance, low ignition temperature (Ti) was observed for all binder based pellets.
... For the investigation of carbon flows among pyrolysis products, several retention times (0.5, 1, 2 h) and inert gas flow rates (0.5, 1, 1.5 L/min) were tested. Pyrolysis conditions were chosen based on preliminary findings and previously published studies 22,24,25 . Biochar samples are named B-HF, B-HF25, B-HF50, B-HF75 and B-WB corresponding to the feedstock types defined in Section 2.1. ...
As non-sewered toilets are now the most commonly used sanitation facilities, the faecal sludge management (FSM) sector is starting to be recognised as an important actor for global carbon management....
... Fecal sludge generally contains high concentrations of organic matter and pathogens, which limits its use in the agricultural and plantation sectors due to environmental and health risks (Fakkaew et al., 2018). However, if fecal sludge can be appropriately managed, it has the potential to be a renewable energy resource (Krueger et al., 2020& Ward et al., 2014 with a reasonably high energy content of 1,910.77-4,538.07 cal/g of dry-basis (Andriessen et al., 2019& Muspratt et al., 2014. ...
This study aimed to characterize fecal sludge (FS) combined with sawdust (SD) as non-charcoal briquettes. The combination consists of var.1 (FS 75% : SD 25%), var.2 (FS 50% : SD 50%), and var.3 (FS 25% : SD 75%). Fecal sludge was obtained from the sludge drying bed of a fecal sludge treatment plant (FSTP) in Malang City, and sawdust was obtained from the furniture workshop. Labor scale briquettes were produced, measured and analyzed the calorific value (ASTM D 5865-01), proximate analysis (SNI 06-3730-1995 and SNI 01-6235-2000), sulfur (ASTM D3177), and density (SNI 8021-2020). The characteristic results the moisture content 3.26%-7.57%, volatile matter 48.68%-68.97%, ash content 12.02%-32.97%, fixed carbon 11.44%–26.62%, calorific value 4,237.78–5.158.64 cal/g, sulfur 0.23%–0.41%, and density 0.50-0.68 (g/cm3). Compared with pure fecal sludge briquettes, the addition of sawdust increased the calorific value of fecal sludge briquettes by up to 32% and decreased ash content by up to 40%. All variations met the standard of SNI 8021:2020, except for the density for var.2 and var 3. Based on MCA, the best variation is var.2 with a score of 45 and requires modification for density to meet the standard of SNI 8021:2020.
... The pyrolysis offers a safe and valuable alternative to illegal dumping and unsafe handling of FS by producing valuable products like biochar, improving the physiochemical soil properties and destroying pathogens due to high processing temperatures (Ward et al., 2014 In addition to steam and chemical activation, several studies have investigated the use of other activation methods, such as microwave and electrochemical activation, to produce AC from different biomass. For instance, in a study by Liu et al. (2010), the production of AC from bamboo using microwave activation showed that the resulting AC had a high surface area and pore volume, as well as a high carbon yield and high adsorption potential for organic pollutants. ...
In the global sanitation challenges over the years, sustainable faecal sludge (FS) management has always featured siting Sub-Saharan Africa and developing countries as the most affected. FS is currently being managed through conventional treatment plants, where it goes through a series of stages which include primary and secondary filters, sedimentation tanks, biological trickling filters, and secondary sedimentation tanks before being released into wetlands. While in wetlands it undergoes further biological filtration to remove heavy metals and the remaining nutrients. In Uganda, this system has been used since the 1970s. However, it has faced various challenges, mostly due to the rapidly growing population, poor quality of FS, low FS collection efficiency due to inaccessibility in slum areas, and the long distances moved by trucks to access the treatment plants. The objective of this review is to highlight the gaps in existing FS management practices, the level of involvement of the different stakeholders and their roles. It also highlights the existing policies, and institutional frameworks with challenges and business opportunities that can be harnessed from FS. The study employed a systematic review of literature through identifying, assessing and synthesizing relevant articles. The findings indicate gaps in government partnerships with private sector and academic institutions. Furthermore, there is increased informal participation of private sector in FSM, knowledge gaps among the public concerning FSM services. In conclusion, the government needs to strengthen partnerships with all stakeholders in the FSM sector as well as increase community sensitization about FSM management.
... At high SF, higher fractions of H, O, and C were transferred from the solid fraction to liquid and gas phases. The calorific value of hydrochars increased significantly (p < 0.05) with severity, starting with 22.32 MJ kg −1 before HTC to 28.76 MJ kg −1 at the highest severity (Fig. 1), resembling the calorific value of sub-bituminous coal (Ward et al., 2014). Moreover, strong correlation (R 2 = 0.9) was observed between the two parameters ( Fig. 1). ...
Hydrothermal carbonization (HTC) is an emerging technology that may potentially address sanitation problems and energy scarcity. However, the significance of the parameters that govern HTC (e.g., temperature and time) is not fully understood, in particular for human excreta. A simplified coalification model was used to describe the 'strength' of thermal reactions by combining temperature and time into a single parameter, the severity factor. This study is the first to assess the extent to which a severity coalification model can predict the properties of human-excreta-derived hydrochar for a given severity with different combinations of reaction time and temperature. HTC experiments with raw human excreta were undertaken with 50 mL batch reactors at five different severities. Severity was established with different combinations of temperature (180 °C, 210 °C, and 240 °C) and reaction time based on the severity-factor equation. The resulting hydrochars were tested for combustion properties, and the respective gas emission as well as, physicochemical and surface area parameters. Significant correlations were found between severity and yield (R2 = 0.88), carbon content (R2 = 0.85), and calorific value (R2 = 0.90), with the properties being similar for a given severity but varying with different severities. Hydrochar's contact angle increased from 53.1° to 81.3° with increasing SF, while surface area remained low, ranging from to <1 to 5.1 m2g-1, with no definite correlation to SF. Combustion profiles for a given severity were generally similar, but the ignition, peak, and burnout temperatures differed between severities. Gram-Schmidt curves indicated that gas emission profiles are similar for a given severity but vary with different severities. The main gases emitted in combustion were virtually identical in all treatments, and included CO2, alkenes (C9, C10), CH4, and H2O. It is concluded that many properties of hydrochar can be inferred from the severity factor.
... While most forms of organic matter are unstable in tropical soils, carbon in the form of biochar remains in the soil for hundreds or thousands of years (Clough et al., 2013), and is therefore desirable for the degraded soils in the region. Moreover, pyrolysis effectively eliminates pathogens from fecal matter due to high processing temperatures (Bleuler et al., 2021;Ward et al., 2014). The possible use of fecal matter as feedstock for biochar production as well as sanitized urine through the same pyrolysis process provides opportunities for improving sanitation management that also yields microbiologically safe products for crop production (Woldetsadik et al., 2018). ...
The majority of people in low‐ and middle‐income countries, such as Kenya, lack effective sanitation and waste management systems. Circular bionutrient economy (CBE) is emerging as a framework to safely reuse organic wastes in agriculture. This study aimed to characterize waste and sanitation systems in Kisumu City, Kenya, with a view to exploring opportunities for CBE in the Lake Victoria basin. Sanitation was characterized through a case study approach in a populous informal settlement, and waste was quantified in two markets in the city. The main toilet facility was pit latrine, although there were also some urine‐diverting dry toilets (UDDTs). One toilet served about 36 people. Over a 1‐mo period, the UDDTs yielded approximately 64,400 L of urine, whereas about 67,500 L of fecal sludge was emptied from the pit latrines, out of which only about 33,000 L (48.9%) was properly disposed of. About 3 t of waste was generated daily from the markets, 95% of which was organic, and was disposed of at an open dumpsite. Organic waste, including human excreta, contains large amounts of organic matter and plant nutrients, and can be processed for agricultural nutrient cycles. Additionally, black soldierly larvae can effectively convert organic waste into nutrient‐rich fertilizer and high protein biomass for animal feeds. These results suggest an opportunity for a CBE system in the region for sustainable organic waste management and urban sanitation, and with opportunity to improve livelihoods and equity.
... • If UDDT reuse unacceptable for reasons beyond fear of safety, consider utilizing a third-party service-based model or alternative uses such as biochar (Koetlisi & Muchaonyerwa 2019), briquette (Ward et al. 2014), or fuel (Sharma et al. 2020) production, thermal treatment (Krueger et al. 2021) or incineration for ash production (Niwagaba et al. 2006). • Promote household scale benefits of economics and water savings, reduced flies and odors, and improved individual/family health. ...
Understanding barriers and facilitators to the adoption of sanitation technologies is crucial to the diffusion of these innovations. Urine-diverting dry toilets (UDDTs) have been implemented throughout regions that are lacking improved sanitation. This review applied the Diffusion of Innovation theory to 18 research articles that collected end-user/potential end-user feedback on UDDT pilot projects in low- and lower-middle-income countries to better understand barriers and facilitators to adoption. Results show the main barriers to adoption were beliefs incompatible with UDDT by-product reuse, a lack of supporting infrastructure, high capital costs, and ineffective promotional communication strategies. The benefits promoted by the diffusion agency were often misaligned with the desires and interests of the potential adopters. Ensuring supporting infrastructure was in place and tailoring the promotional communications to the adopters’ perspectives facilitated UDDT adoption. The main facilitator was the perceived relative advantages of the UDDT over existing sanitation options, including fertilizer production. This indicates that safe treatment and reuse processes need to be implemented. Urine diversion was rarely mentioned as a barrier. These findings can help communities and organizations working to increase sanitation technology adoption in low-income, rural areas by better understanding common barriers and facilitators to adoption.
HIGHLIGHTS
• Collection and reuse of human waste as fertilizer is the main facilitator to adoption but may be incompatible with existing beliefs.;
• Providing ongoing training on safe emptying or creating an emptying/reuse service is crucial to successful UDDT implementation.;
• Ensuring sufficient ash or dry material facilitates dry sanitation adoption.;
• Propagators of UDDTs should focus on household scale economic, water, user experience, and health benefits.;
• Urine diversion was not a barrier to technology adoption.;
... In addition, pyrolysis technology can serve multiple purposes simultaneously, such as killing parasites and pathogens, reducing the volume of feces, and stabilizing organic components (Chen et al. 2014;Konczak and Oleszczuk 2020;Du et al. 2022). NASA studied the pyrolysis of synthetic human feces for waste volume reduction and resource recovery on space station (Serio et al. 2001(Serio et al. , 2002Ward et al. 2014). ...
Pyrolysis carbonization of human feces has shown potential for converting feces biomass into a soil amendment. However, little is known about the interactions of DOM derived from feces-based biochar produced at low-temperature with heavy metals (HMs). In this study, the binding properties of Pb(II) and Zn(II) with DOM derived from feces-based biochar produced at low pyrolysis temperatures were investigated using EEM-PARAFAC combined with general, and moving-window two-dimensional correlation analyses (2D-COS). The results revealed that DOM from biochar produced at 280 °C exhibited a higher Pb(II) and Zn(II) affinity and more binding sites than DOM produced at 380 °C. The fulvic-like and humic-like components exhibited obvious fluorescence quenching after the heavy metal addition, and the complexes formed with Pb(II) and Zn(II) were more stable. C-H groups exhibited the fastest response to Pb(II) and Zn(II) binding in the FB280 DOM, while the COO- groups of carboxylic acids in the FB380 DOM exhibited the fastest response to Pb(II) and Zn(II). Moreover, the mutation concentration range of components and functional groups in DOM, as analyzed by MW2D-COS, was greater for Zn(II) than for Pb(II). These results provide a more detailed molecular-level understanding of the interaction mechanisms between heavy metals and feces-based biochar-derived DOM and the effect of HM concentration on DOM binding. Further, these results will help to provide a reasonable reference for feces management and feces-based biochar in controlling soil HMs.
Graphical Abstract
... 15,16 Biochar can also be used to produce briquettes that can be used as a fuel for cooking or heating. 17 Additionally, the produced thermal energy from pyrolysis can be converted to electrical energy or leveraged to dry influent fecal sludge. 18,19 While the moisture content of fecal sludge may be considered an obstacle to thermal treatment, dewatering followed by drying with the produced thermal energy can achieve the minimum requirements in many cases. ...
Omni Processors (OPs) are community-scale systems for non-sewered fecal sludge treatment. These systems have demonstrated their capacity to treat excreta from tens of thousands of people using thermal treatment processes (e.g., pyrolysis), but their relative sustainability is unclear. In this study, QSDsan (an open-source Python package) was used to characterize the financial viability and environmental implications of fecal sludge treatment via pyrolysis-based OP technology treating mixed and source-separated human excreta and to elucidate the key drivers of system sustainability. Overall, the daily per capita cost for the treatment of mixed excreta (pit latrines) via the OP was estimated to be 0.05 [0.03-0.08] USD·cap-1·d-1, while the treatment of source-separated excreta (from urine-diverting dry toilets) was estimated to have a per capita cost of 0.09 [0.08-0.14] USD·cap-1·d-1. Operation and maintenance of the OP is a critical driver of total per capita cost, whereas the contribution from capital cost of the OP is much lower because it is distributed over a relatively large number of users (i.e., 12,000 people) for the system lifetime (i.e., 20 yr). The total emissions from the source-separated scenario were estimated to be 11 [8.3-23] kg CO2 eq·cap-1·yr-1, compared to 49 [28-77] kg CO2 eq·cap-1·yr-1 for mixed excreta. Both scenarios fall below the estimates of greenhouse gas (GHG) emissions for anaerobic treatment of fecal sludge collected from pit latrines. Source-separation also creates opportunities for resource recovery to offset costs through nutrient recovery and carbon sequestration with biochar production. For example, when carbon is valued at 150 USD·Mg-1 of CO2, the per capita cost of sanitation can be further reduced by 44 and 40% for the source-separated and mixed excreta scenarios, respectively. Overall, our results demonstrate that pyrolysis-based OP technology can provide low-cost, low-GHG fecal sludge treatment while reducing global sanitation gaps.
... Biochar can strongly retain several organic contaminants in environmental media, thus reducing environmental risks associated with contaminants and the reconditioning needs once applied (Kołodynska et al., 2018;Weber and Quicker, 2018). Biochars have various potential benefits, such as use as an adsorbent (Koetlisi and Muchaonyerwa, 2017); soil amendment (Woldetsadik et al., 2018); carbon sequestration; solid fuel (Ward et al., 2014) and also the treatment of sludge through combustion in waste management (Smith et al., 2009;Joseph and Lehmann, 2015). Studies have also successfully examined the incorporation of biochar for sanitation purposes to manage faecal sludge (Krueger et al., 2020). ...
Biochar is a valuable treatment option for faecal sludge management (FSM). However, the sanitation application rates of biochar in FSM are not well established. There is also a gap in knowledge about the effect of actual raw sewage effluent and sludge on organic and inorganic contaminants migration of biochar treated soil. This study investigated the concentration and migration rates of N, P, E. coli and faecal coliform bacteria through different soil-bed biochar column treatments leached with raw faecal sludge and sewage effluent. Forty-four soil-bed leaching columns with pinewood biochar rates at 5, 10 and 20 t/ha were set at the Bloemspruit wastewater plant, South Africa. The pinewood biochar used had a pH of 10.21, total C composition of 92%, surface area of 517 m²/g, and a pore size of 1.7 nm. It was found that the 20 t biochar per ha treatment with faecal sludge increased water retention (flows of 33 mm/hr. at 0 t/ha compared to 0.8 mm/hr. at 20 t/ha) and leachates purification. High detections were observed for faecal coliforms and E.coli above 4331 CFU/100 mL from the effluent and faecal sludge in soils without biochar. Detection of E.coli at 20 t/ha decreased to 1 CFU/100 mL while the faecal coliforms still had counts above 10 CFU/ 100 mL. The results showed a decreasing rate of nitrates, phosphates, zinc and copper with an increasing biochar application rate. Pinewood biochar showed significant removal efficiencies of bacteria (between 89 – 98%) and nitrates and phosphates (between 68 – 98%). Significant differences were seen at P < 0.05 between the means of the treatments with and without biochar. The results from the study show that pinewood biochar applied at rates between 5 and 20 t/ha has a high organic and inorganic contaminants reduction potential for FSM.
... Binding materials like molasses, lime, and starch binders were used for producing the briquettes. The final CV were comparable to commercial charcoal briquettes, concluding that fecal char briquettes contributes to the preservation of the environment, substituting charcoal and firewood (Ward et al., 2014). On balance, the production of dung-based briquettes is a matter of research, although only a few articles have been published in the last decades. ...
Solid waste management and the increasing energy demand are a global concern. Waste can play the role of alternative fuel, partly reducing the environmental footprint in the waste management sector. Waste briquetting is used as a treatment option for improving waste combustion efficiency, as well as its management and handling. This critical review aims at evaluating the potentialities of this method as a possible solution to introduce alternative fuels in developing countries. Totally, 85 scientific articles available from 1999 to 2021 from international databases were reviewed, and a SWOT analysis has been conducted following the indications underlined in the scientific literature. The outcomes of the review highlight that agricultural waste-based and wood-based briquettes are the most investigated, followed by plastics-based briquettes and paper & cardboard-based briquettes. Waste-based briquettes can be divided into three categories, function of the calorific value: biomass-based (16.22 ± 1.65 MJ kg⁻¹), wood-based (19.03 ± 2.46 MJ kg⁻¹), and plastics and charcoal-based briquettes (24.64 ± 5.29 MJ kg⁻¹). Review findings underline that in-door emissions analysis is lacking, as well as research related to the water boiling test for the valorisation of waste briquetting for cooking and heating systems in developing countries. The current review contributes to highlighting the importance in implementing appropriate technologies for energy production and waste management in developing countries.
... Char quality and properties are determined by pyrolysis parameters including heating duration, maximum temperature, pressure, and oxygen content, which can vary with different feedstock [25]. Ward et al. [26] and Harussani et al. [27] mentioned that the characteristics and attributes of the char are mainly depend in high extent of the composition of the waste to be pyrolysed. Thus, it will affect its surface area and porosity. ...
The importance of carbon-based nanomaterials for various uses in today's world has prompted efforts to develop simple, cost-effective synthesis methods from abundantly available wastes. By thermally processing organic waste, pyrolysis in a broad spectrum is commonly used for the creation of carbon nanostructures. The growth of carbon nanomaterials is a difficult process that is heavily controlled by temperature, catalyst, and precursor type. Significant progress has been achieved in refining nanomaterial growth techniques in recent years, opening up new avenues for commercial carbon-based nanomaterial production. In this study, different pyrolysis techniques for the synthesis of carbon-based nanomaterials, specifically carbon nanotubes (CNTs), carbon nanofibers (CNFs), and graphene, are examined (G). The features of carbon-based composites are described in this review article for their specific application in defence sectors such as aeronautics, maritime-naval ships and submarines, automobiles, electronics, EMI shielding, and constructions.
... Char quality and properties are determined by pyrolysis parameters including heating duration, maximum temperature, pressure, and oxygen content, which can vary with different feedstock [25]. Ward et al. [26] and Harussani et al. [27] mentioned that the characteristics and attributes of the char are mainly depend in high extent of the composition of the waste to be pyrolysed. Thus, it will affect its surface area and porosity. ...
The importance of carbon-based nanomaterials for various uses in today's world has prompted efforts to develop simple, cost-effective synthesis methods from abundantly available wastes. By thermally processing organic waste, pyrolysis in a broad spectrum is commonly used for the creation of carbon nanostructures. The growth of carbon nanomaterials is a difficult process that is heavily controlled by temperature, catalyst, and precursor type. Significant progress has been achieved in refining nanomaterial growth techniques in recent years, opening up new avenues for commercial carbon-based nanomaterial production. In this study, different pyrolysis techniques for the synthesis of carbon-based nanomaterials, specifically carbon nanotubes (CNTs), carbon nanofibers (CNFs), and graphene, are examined (G). The features of carbon-based composites are described in this review article for their specific application in defence sectors such as aeronautics, maritime-naval ships and submarines, automobiles, electronics, EMI shielding, and constructions.
... Solar drying of fecal sludge from pit latrines in bench-scale tests resulted in an average drying rate between 0.5 and 0.8 kg/h/m 2 (Septien et al. 2018). Ward et al. (2014) investigated a solar-powered pyrolysis reactor known as the Sol-char toilet to convert fecal sludge from pit latrines into pathogen-free biochar. Another solar thermal water heater system was tested at laboratory scale to dry and disinfect fecal sludge (Sweya & Mgana 2020). ...
On-site sanitation systems such as pit latrines are extensively used around the world, while there is a growing number of evidence documenting the impact of pit latrines on groundwater quality that may affect human health. Hence, this paper summarizes the various safe-sanitation technologies by broadly categorizing them into fecal pathogen disinfection methods (anaerobic digestion, chemical disinfection, biological additives, solar pasteurization and vermicomposting) and capturing methods (pit lining and permeable reactive barriers, the latter of which simultaneously capture and sanitize fecal sludge in pit latrines). While some of the reviewed technologies have been widely practiced for mitigating microbial contamination of the groundwater, others are still in the early stage of commercialization and field validation. Though there are challenges to the selection and adoption of the most appropriate technology, this paper discusses the readiness of each technology as a stand-alone fecal sludge management solution. HIGHLIGHTS
Pit latrines impact groundwater quality that may affect human health.;
Low-cost treatment techniques are discussed to capture and treat pathogens in pit latrines.;
Pit liners such as peat, clay, hydrophobic membranes and permeable reactive barriers help capture pathogens.;
When compared with other methods, the chemical disinfection method with chlorine, lime, Ikati and Soda ranked best with the highest score.;
... N/mm 2 for briquettes with 30-40% moisture content produced using 10 wt% cassava starch as a binder and those results are less than the ones (0.09-0.42 N/mm 2 ) obtained in this study. According to Turkish Standard (TS)12055, Class I briquettes should have a compressive strength greater than 13 N/mm 2 , while Class II briquettes should withstand a compressive strength not lower than 10 N/mm 2 (Haykiri-Acma, Yaman, and (Ward, Yacob, and Montoya 2014). ...
This study investigated the use of African Elemi (Canarium Schweinfurthii) resin as a binder for the production of carbonized briquettes from charcoal fines. The binder and charcoal fines were characterized through proximate analysis, ultimate analysis, higher heating value, and SEM. Four briquette samples (B25, B30, B35, and B40) with a ratio of charcoal fines: binder of 3:1, 7:3, 13:7, and 3:2, respectively, were produced at a compaction pressure of 5.92–7.96 MPa. The physical properties of the briquettes determined were bulk density, impact resistance index (IRI), compressive strength, splitting tensile strength, water resistance index (WRI), and morphology. The chemical properties of the briquettes determined were proximate analysis, ultimate analysis, higher heating value (HHV), and energy density. One-way ANOVA and Fisher’s LSD were used to analyze the chemical properties of briquettes. The briquettes had a bulk density of 0.770–1.036 g/cm³, IRI of 2.90–73.33, compressive strength of 2.25–10.94 N/mm², splitting tensile strength of 0.09–0.42 N/mm², WRI of 99.26–99.29, and an HHV of 29.7–31.3 MJ/kg. The briquette properties were found to be comparable to results from other studies.
... Pellets, unlike coal, are renewable, carbon-based, and possess high-calorific energy that finds application in various industries (Mitchual et al. 2013). A recent study has reported the use of fecal-char pellets for heating purposes (Ward et al. 2014). The characterization of manufactured pellets is to be tested for calorific value, ash content, moisture content, fixed carbon content, and Thermogravimetric analysis (Oliveira et al. 2017). ...
The conversion of agro-residues to value added products is a potential opportunity for all agrarian countries. This study involves the utilization of agro-waste sourced from farmlands, and plant foliage waste collected from university premises, both blended with the distillery sludge in a ratio of 1:1 to prepare pellets. The pellet samples were tested with proximate analysis and ultimate analysis. The gross calorific value of the coal sample was 8967.23 kcal/kg, whereas the plant waste and sludge blend sample indicated a value of 7121.70 kcal/kg. The pellets produced from farm waste and sludge showed a value of 8621.334 kcal/ kg which is close to the gross calorific value of coal. The burning rate of the pure coal was found to be the highest with a value of 0.156 mg/min, followed by a mixture of farm waste and sludge with 0.129 mg/min and a blend of plant waste and sludge with 0.00745 mg/min, respectively. This research highlights the possibility of converting distillery sludge, plant waste, and farm waste into alternate fuel source.
... It is anticipated that the fecal waste can be converted to char with longer times on sun, and with improved insulation around the receiver. Human fecal chars have been shown to have a higher heating value (HHV) comparable to that of cooking and heating fuels commonly used throughout the world, such as wood charcoal or bituminous coal [46]. ...
Almost half of the world’s population is living without access to sanitation services that are safe, reliable, and minimize public health risk of human waste exposure. Modern flush-based sanitation networks are unsustainable: substantial resources, namely water and fuel, are required to bring human waste to centralized treatment facilities. Moving toward sustainable sanitation requires the implementation of innovative renewable energy technologies for stabilization and disinfection of waste, at the local or household scale, where minimal inputs of water, electricity or chemicals are required. A novel solar thermal disinfection toilet prototype has been constructed and is assessed for overall solar to receiver efficiency in treating waste without electrical, chemical, or water inputs from municipal supply. The measured solar to receiver efficiency is 28%, incorporating the capturing and concentration of sunlight and transmission of the energy to the receiver. For a typical sunny day, the current system can achieve thermal treatment of 0.8 kg human waste in roughly 100 min. The novel toilet is available for any location in the world with sufficient sunlight and irradiance data, and is scalable by adding solar collectors for sizes from single dwellings to communities.
... The negative side is more pronounced because it generates some of the major environmental and health difficulties faced by people living in poor societies, comprising of water pollution and the transmission of diseases and infections which affects around 2.5 billion people in unindustrialized countries with 300 million people from Africa [3][4]. Fitting and operating sewage plus wastewater treatment plants is costly and conventional wastewater management is not an ecologically friendly process since so much energy is utilized and has disposal complications issues [5]. Consequently, due to cost, many areas in the developing nations have opted out [4]. ...
... Despite the potentials provided by the use of faecal waste for biogas production, the technology is still beset by acceptability and sociocultural issues (Buit and Jansen 2016). Thus, a deep understanding of the acceptability and sociocultural issues surrounding faecal waste becomes very important if the deployment of faecal waste-to-biogas plants are to be successful (Ward et al. 2014). ...
The use of wastes for biogas production has been restricted to few feedstock like cattle manure and food waste. Increasing the feedstock base for biogas production is capable of increasing the sustainability of feedstock availability. This study seeks to assess sociocultural and acceptability issues associated with the use of faecal waste (human excreta, cattle manure, etc.) as a source of energy in selected stakeholder areas in Benin City, Nigeria. Qualitative research methods were used for data collection as data were generated through survey questionnaire. Field responses were mined and analysed using Factor analysis and cluster plots generated from Factor plots were analysis using Statistical Program for Social Sciences to rank the variables in order of hierarchical means. Analyses from this study have shown that faecal waste is a dependable feedstock for biogas production while adding value to food production through digestate utilization. Furthermore, high factor loading of 0.759 for acceptance to the fact that biogas from faecal waste has the potential to improve environmental sanitation in Benin City. However, there exist considerable knowledge gap as shown in the analyses which suggest a need for continuous awareness creation, policy formulation and orientation on the importance of biogas production from a range of feedstock in tackling energy security and sustainability in line with SDGs 2, 6 and 7.
... • Fecal matter • Starch, molasses, lime • [62] Textile industry solid waste • Biosludge, cotton residue. ...
Growing global demand and utilization of fossil fuels has elevated wealth creation, increased adverse impacts of climate change from greenhouse gases (GHGs) emissions, and endangered public health. In most developing countries, biomass wastes, which include but are not limited to agricultural residues, are produced in large quantities annually. They are either inefficiently used or disposed of indiscriminately, which threatens the environment. It is possible to convert these wastes, through densification, into high-density and energy-efficient briquettes. Densification of biomass into briquettes presents a renewable energy option as an alternative to fossil fuels. This paper reviews biomass briquetting with reference to biomass resources, feedstock pre-processing, briquetting process parameters, briquetting technology, and briquettes quality evaluation parameters. The review also includes the economic aspect of briquetting relating to costs and feasibility.
... The potentiality of nutrient recycling from faeces through pyrolysis was calculated based on literature data [35][36][37][38]. The average biochar production from faeces and other waste bio-solid were considered for calculating biochar production rate while the average concentration of C, N, P and K in the biochar was used for calculating nutrient content in the faeces biochar. ...
Biological organisms including humans require mineral nutrients for their growth and development. A significant amount of these nutrients remain unused in the left over materials, known as waste, causing environmental degradation. These nutrients could potentially be a resource for agriculture if recycled and reused. Therefore, a critical examination of nutrient loading from waste such as from human excretion and biowaste is required. Here, we estimated the nutrient loading from municipal organic waste (MOW) and human excreta using linear modelling, explored the potential consequences to ecosystem services and proposed several management strategies. Waste and human excreta generation were calculated from the per capita generation rate while nutrient concentrations were considered as the average of literature values. The daily carbon (C), nitrogen (N), phosphorus (P) and potassium (K) loading from MOW, urine and faeces to water bodies around the major cities in Bangladesh were estimated at 2158, 112, 58 and 91 t, respectively. The nutrient loading to water bodies reduces several ecosystem service with estimated cost of BDT. 42.93 million for the reduction in fish production and half of property rent. Combined pyrolysis and composting of municipal organic waste can reduce the volume of organic waste Similarly, pyrolysis of faeces and then, sorption of nutrients using the produced biochar could recycle 440 t C, 71 t N, 113 t P and 73 t K day−1.Combing the nutrient recycling through pyrolysis-composting of MOW and faeces pyrolysis-sorption of nutrients from urine, the estimated nutrient recycling was 39% C, 11% N, 68% P and 11% K of the intrinsic nutrients in waste. Altogether, our study provides a comprehensive understanding of nutrient loading, its consequences and potential recycling options that may help to attain environmental sustainability.
The production–consumption cycle needs a transition towards a circular economy where waste valorization is included. This study investigated briquetting as a stabilization method for black soldier fly frass (BSFF) with faecal matter, pig manure, and poultry manure as the larvae feed. Herein, dried BSFF was pyrolyzed at 350 °C for 2 h to produce biochar then mixed with charcoal dust in equal ratio to produce biobriquettes through densification, with cassava gel (10 wt%) as binder. One-way ANOVA showed statistical significance in carbon, nitrogen, hydrogen, and oxygen. There were significant differences (p < 0.05) between the calorific value, moisture content, ash content, volatile matter, and fixed carbon of the briquettes. The fixed carbon, volatile matter, moisture, and ash content ranged from 29.66 ± 0.86 to 42.01 ± 0.92, 29.26 ± 0.52 to 32.59 ± 0.80, 2.95 ± 0.1 to 5.08 ± 0.04, and 21.48 ± 0.14 to 37.20 ± 0.29, respectively. The calorific value of the produced briquettes ranged from 16.25 ± 0.57 to 20.70 ± 0.53 MJ/kg, which exceeds the minimum requirement of 14.5 MJ/kg recommended for non-woody briquettes. During combustion, concentrations of NOx, N2O, CO, and CO2 varied significantly across the treatments with the acacia charcoal having the highest concentration of CO. Briquetting is a potential stabilization method for frass resulting in waste reduction, bioenergy production, reduced adverse effects of climate change, and enhanced sustainability.
The unsystematic utilization of agricultural wastes has resulted into health hazard and environmental pollution. A potential solution to the afore-mentioned problems is to use these waste for sustainable energy production and supply such as renewable energy technologies. This research is carried out to study the combustion properties of briquettes produced from carbonized rice husk using gum Arabic and starch as binders at varying concentration weight of 25%, 30%, 35%, 40% and 45% with the constant weight of 100g of the substrate. A simple extruder briquette machine was fabricated to facilitate the densification of the biomass. The calorific value increased with the increase in binder concentration. The burning rate shows that briquettes with little amount of binder burnt off faster, the rate of burning decreased with the increase in binder amount. The ignition time decreased with the increase in binder amount. Gum Arabic of 45%, boiled 250ml of water in 18 minutes while the same ratio for starch binder boiled the same quantity in 14 minutes; from the results gotten 45% starch binder has the best positive outstanding results compared to other concentrations.
Hydrothermal carbonization (HTC) represents elegant thermochemical conversion technology suitable for energy and resource recovery from wet biowaste, while the elemental nitrogen is bound to affect the HTC process and the properties of the products. In this review, the nitrogen fate during HTC of typical N-containing-biowaste were presented. The relationship between critical factors involved in HTC like N/O, N/C, N/H, solid ratio, initial N in feedstock, hydrothermal temperature and residence time and N content in hydrochar were systematic analyzed. The distribution and conversion of N species along with hydrothermal severity in hydrochar and liquid phase was discussed. Additionally, the chemical forms of nitrogen in hydrochar were elaborated coupled with the role of N element during hydrochar formation mechanism and the morphology features. Finally, the future challenges of nitrogen in biowaste involved in HTC about the formation and regulation mechanism of hydrochar were given, and perspectives of more accurate regulation of the physicochemical characteristics of hydrochar from biowaste based on the N evolution is expected.
More people globally are now using on-site sanitation technologies than sewered connections. The management of faecal sludge generated by on-site facilities is still challenging and requires an understanding of all sanitation service chain components and their interactions; from source conditions to treatment and resource recovery. This study aimed to improve the current lack of knowledge regarding these interactions, by establishing a quantifiable relationship between human excreta source separation and resource recovery via pyrolysis. The effects of source separation of faeces and urine on biochar quality were investigated for different pyrolysis temperatures (450 °C, 550 °C, 650 °C) and this information was used to assess energy and nutrient recovery. Results quantify the benefits of urine diversion for nitrogen recovery (70% of total N losses during thermal treatment avoided) and show an increase in the liming potential of the produced faecal-based biochars. The quality of produced solid fuels is also improved when source-separated faeces (SSF) are used as a feedstock for pyrolysis, including a 50% increase in char calorific value. On the other hand, biochars from mixed urine and faeces (MUF) are more rich in phosphorus and potassium, and surface morphology investigation indicates higher porosity compared to SSF biochars. The high salinity of MUF biochars should be considered before agricultural applications. For both biochar types (SSF, MUF), the presence of phosphate compounds of high fertiliser value was confirmed by X-ray diffraction analysis, and temperatures around 500 °C are recommended to optimise nutrient and carbon behaviour when pyrolysing human excreta. These findings can be used for the design of circular faecal sludge management systems, linking resource recovery objectives to source conditions, and vice-versa. Ultimately, achieving consistent resource recovery from human excreta can act as an incentive for universal access to safe and sustainable sanitation.
Human feces contain a lot of nutrients and organic matter, which can be used in many fields. In this study, biochar (HFBC) was prepared at 300, 500 and 800 °C using human feces as substrate, and the characteristics of HFBC prepared at different pyrolysis temperatures were investigated. It was confirmed that HFBC prepared at 800 ℃ (HFBC-800) had a better pH buffer capacity, more proportion of π-π shake-up satellites, better graphitization degree and higher conductivity, which could promote the efficiency of biohydrogen production of bacteria. Furthermore, the biohydrogen production of Thermoanaerobacterium thermosaccharolyticum M18 using different concentrations of simulated human feces (SHF) was further investigated. The best biohydrogen production was found for 40 wt%-SHF, with 128.54 mmol H2/L produced in 180 h. The highest biohydrogen production of 148.75 mmol H2/L was obtained by adding 6 g/L HFBC-800 to the biohydrogen production process. This study provides a feasibility for high-performance hydrogen production from human feces and presents an insight into the resource utilization of human waste.
An innovative twin auger pyrolysis reactor for the intermediate conversion of partially wet sanitary faecal sludge generated on train toilets (mobile applications) is designed and successfully commissioned. The effects of operating temperature, feedstock feeding rates and moisture content and their interaction on the distribution and properties of product biofuels with the use of no carrier gas were assessed. Approximate yields of 50 %, 40 % and 10 % were observed for the biooil, syngas and biochar respectively at 500 °C. Meanwhile, the highest calorific value (HHV) of the syngas did not exceed 10 MJ/Nm3. Acidic compounds (10 % RPA) and nitrogen-containing hydrocarbons (18 % RPA) substituted the abundant species in biooil fraction at 500 °C with the lowest feed volumes of feedstock. Biochar presented the highest fixed carbon (58 %) and ash content (37 %) upon higher operating temperatures for the minimum and maximum volumes of feedstock. Interestingly, the retention of inorganics within the structure of char were observed. Meanwhile, the calorific value of the biochar reduced due to intensive reduction reactions at higher temperatures ranging to a minimum of 19 MJ/kg. Effects of reactor design and configuration on the pyrolytic products are discussed accordingly and further implications are provided. Overall, extensive further research for the end-use of pyrolytic products and the investigation of emissions, upon energy recovery or land-application of by-products are suggested.
Background: The provision of safe sanitation services is essential for human well-being and environmental integrity, but it is often lacking in less developed communities with insufficient financial and technical resources. Hydrothermal carbonization (HTC) has been suggested as an alternative sanitation technology, producing value-added products from faecal waste. We evaluated the HTC technology for raw human waste treatment in terms of resource recovery. In addition, we constructed and tested a low-cost HTC reactor for its technical feasibility.
Methods: Raw human faeces were hydrothermally treated in a mild severity range (≤ 200 °C and ≤ 1 hr). The total energy recovery was analysed from the energy input, higher heating value (HHV) of hydrochar and biomethane potential of process water. The nutrient contents were recovered through struvite precipitation employing process water and acid leachate from hydrochar ash. A bench-scale low-cost reactor (BLR) was developed using widely available materials and tested for human faeces treatment.
Results: The hydrochar had HHVs (23.2 - 25.2 MJ/kg) comparable to bituminous coal. The calorific value of hydrochar accounted for more than 90% of the total energy recovery. Around 78% of phosphorus in feedstock was retained in hydrochar ash, while 15% was in process water. 72% of the initial phosphorus can be recovered as struvite when deficient Mg and NH 4 are supplemented. The experiments with BLR showed stable operation for faecal waste treatment with an energy efficiency comparable to a commercial reactor system.
Conclusions: This research presents a proof of concept for the hydrothermal treatment of faecal waste as an alternative sanitation technology, by providing a quantitative evaluation of the resource recovery of energy and nutrients. The experiments with the BLR demonstrate the technical feasibility of the low-cost reactor and support its further development on a larger scale to reach practical implementation.
This study investigated the potential of using locally available municipal solid wastes (MSW) (such as food wastes from restaurants, charcoal dust, coconut husk and shell, and sawdust) as feedstock to produce non-carbonized fuel briquettes. A low-cost briquetting machine sourced from Alfaster Industries in Kenya served to demonstrate the concept. Using decomposed food waste resulted in briquettes with higher bulk density (+4%), greater net calorific value (+18%) and lower burning rate (-24%), compared to the use of regular food waste. There was no significant difference in ash content from the two briquette types. The results also indicate that decomposing food waste and mixing it with tree-based raw materials such as coconut waste, charcoal waste or sawdust improves the quality of briquettes, and enhances the temperatures achieved during combustion. This recycling solution has the potential to serve multiple benefits in MSW management for sustainable cities while reducing rural land degradation and deforestation.
Background: The provision of safe sanitation services is essential for human well-being and environmental integrity, but it is often lacking in less developed communities with insufficient financial and technical resources. Hydrothermal carbonization (HTC) has been suggested as an alternative sanitation technology, producing value-added products from faecal waste. We evaluated the HTC technology for raw human waste treatment in terms of resource recovery. In addition, we constructed and tested a low-cost HTC reactor for its technical feasibility.
Methods: Raw human faeces were hydrothermally treated in a mild severity range (≤ 200 °C and ≤ 1 hr). The total energy recovery was analysed from the energy input, higher heating value (HHV) of hydrochar and biomethane potential of process water. The nutrient contents were recovered through struvite precipitation employing process water and acid leachate from hydrochar ash. A bench-scale low-cost reactor (BLR) was developed using widely available materials and tested for human faeces treatment.
Results: The hydrochar had HHVs (23.2 - 25.2 MJ/kg) comparable to bituminous coal. The calorific value of hydrochar accounted for more than 90% of the total energy recovery. Around 78% of phosphorus in feedstock was retained in hydrochar ash, while 15% was in process water. 72% of the initial phosphorus can be recovered as struvite when deficient Mg and NH 4 are supplemented. The experiments with BLR showed stable operation for faecal waste treatment with an energy efficiency comparable to a commercial reactor system.
Conclusions: This research presents a proof of concept for the hydrothermal treatment of faecal waste as an alternative sanitation technology, by providing a quantitative evaluation of the resource recovery of energy and nutrients. The experiments with the BLR demonstrate the technical feasibility of the low-cost reactor and support its further development on a larger scale to reach practical implementation.
This study explored the production and evaluation of briquettes made from dried fecal sludge mixed with fresh food waste as a dual strategy to solve energy poverty and poor sanitation problems in Ugandan slums. Cylindrical briquettes measuring 82 mm height by 76 mm diameter were produced from dried fecal sludge (FS) alone, and FS mixed separately with pineapple peels (FS + PP), charcoal fines (FS + CD), and bean husks (FS + BH) in a mix ratio of 50% FS: 50% biomass (wt/wt basis) using red soil as the binder. Physiochemical characteristics and fuel thermal efficiency of the briquettes were tested following ASTM standards and were compared to wood-derived charcoal and commonly traded briquettes on market in Uganda. The average moisture content was 5.1%. Bulk density was highest in FS briquettes (1.12 g/cm³) and lowest in FS + BH (0.847 g/cm³). Volatile matter (VM) was highest in FS + PP (39%) and lowest in FS alone (25.7%). The average ash content was 30.4%. FS + PP had the highest calorific value (17.92 MJ/kg) while FS alone had the lowest (6.19 MJ/kg). The highest burning rate was recorded in FS + CD briquettes (8 g/min) and was lowest in FS + PP (4 g/min). Based on the calculated burning rates and calorific values, the economic advantage calculations implied that blending one ton of dry FS with one ton of dry pineapple peels for fuel briquettes, and their use as a substitute could save consumers about USD 620 per ton of wood charcoal foregone.
Sludge treatment is an integral part of faecal sludge management in non-sewered sanitation settings. Development of pyrolysis as a suitable sludge treatment method requires thorough knowledge about the properties and thermal decomposition mechanisms of the feedstock. This study aimed to improve the current lack of understanding concerning relevant sludge properties and their influence on the thermal decomposition characteristics. Major organic compounds (hemicellulose, cellulose, lignin, protein, oil and grease, other carbohydrates) were quantified in 30 faecal sludge samples taken from different sanitation technologies, providing the most comprehensive organic faecal sludge data set to date. This information was used to predict the sludge properties crucial to pyrolysis (calorific value, fixed carbon, volatile matter, carbon, hydrogen). Samples were then subjected to thermogravimetric analysis to delineate the influence of organic composition on thermal decomposition. Septic tanks showed lower median fractions of lignin (9.4%dwb) but higher oil and grease (10.7%dwb), compared with ventilated improved pit latrines (17.4%dwb and 4.6%dwb respectively) and urine diverting dry toilets (17.9%dwb and 4.7%dwb respectively). High fixed carbon fractions in lignin (45.1%dwb) and protein (18.8%dwb) suggested their importance for char formation, while oil and grease fully volatilised. For the first time, this study provided mechanistic insights into faecal sludge pyrolysis as a function of temperature and feedstock composition. Classification into the following three phases was proposed: decomposition of hemicellulose, cellulose, other carbohydrates, proteins and, partially, lignin (200–380 °C), continued decomposition of lignin and thermal cracking of oil and grease (380–500 °C) and continued carbonisation (>500 °C). The findings will facilitate the development and optimisation of faecal sludge pyrolysis, emphasising the importance of considering the organic composition of the feedstock.
Hydrothermal carbonization (HTC), as one of the thermal conversion techniques, shows promising commercial potential for hydrochar production from wet biowaste. This technique was re-discovered and regraded as artificial coalification to mimic natural process. In recent years, researchers concern more about hydrochar obtained from HTC, since large amount of organic waste including sludge, algae, food waste, manure etc. are generated with high moisture, which can be directly used as reaction medium, and hydrochar has high carbon density and energy retention. With this regard, application of hydrochar as biofuel is a renewable and sustainable way for biowaste recycling. In this review, HTC process and pathways about hydrochar formation from (N-free/N-rich biowaste), carbon-skeleton structure, critical elements on clean properties, and hydrochar pelletization for biofuel production were presented. Potential applications and challenges for HTC as green and sustainable way were presented, which will provide prospect for hydrochar as clean and renewable biofuel.
Char, a solid product obtained from carbonization of waste Poly(Ethylene) Terephthalate (PET), has high potential to solve the current plastic waste problem through the synthesis of new carbon-based adsorbents. However, thermal degradation reaction of polymer involves multiple series of complex reaction pathways and the formation of char is not clarified. In this study, the phase behavior of PET carbonization and the mechanism of char formation was studied in detail. Based on the van Krevelen diagram, it is evident that rapid thermal decomposition of PET occurs through decarbonylation to form char and decarboxylation to form wax. Based on the analysis of cross-linking behavior, a correlation between the degree of cross-linking as a function of CO and CO2 and dependent parameters based on the experimental operation was obtained. The findings validified the assumption that scission of CO bond in the carbonyl group through decarbonylation and decarboxylation to release CO and CO2 leads to the formation of char. The cross-linking behavior was further clarified by studying the distribution of cross-linking structure in char and wax. It was confirmed that decarbonylation reaction to release CO is highly associated with the formation of cross-linking to form char in the solid residue, whereas decarboxylation reaction to release CO2 is highly associated with the formation of cross-linking to form aromatic compounds in the wax residue.
Informal milk marketing chains provide the major milk supply link from smallholder dairy production systems to consumers in developing countries. Prevalence risk of antibiotic residues was investigated in milk samples (n=528) collected from different levels of informal supply chains in Pakistan from 2012-2013. After screening, all positive samples were further analyzed by High Performance Liquid Chromatography to quantify individual β-lactam residues. Fifteen percent of the total samples were found to be positive for at least one of the antibiotics. All positive samples (81/528) were positive for amoxicillin. Percentage of positive samples for ampicillin and penicillin was 12.1 and 6.4% respectively. Percentages of positive samples collected from farmers, small collectors, large collectors and retailers were 17.5, 15.1, 8.3 and 13.5 respectively. When relating to season of collection 11.3, 10.2, 19.1, 17.9 and 16.3% of samples in autumn, monsoon, spring, summer and winter were found positive. Concentrations of amoxicillin, ampicillin and penicillin in positive samples were 79.5±12.15, 106.6±12.49 and 13.7±4.2µgkg-1 respectively. Occurrence of these high levels of drug residues demand mass awareness programs associated with the implementation of legislation and its enforcement designed to protect the consumer.
Pyrolysis processing is one of several options for solid waste resource recovery in space. It has the advantage of being relatively simple and adaptable to a wide variety of feedstocks and it can produce several usable products from typical waste streams. The overall objective of this study was to produce a prototype mixed solid waste pyrolyzer for spacecraft applications. A two-stage reactor system was developed which can process a maximum of about 0.5 kg of waste per cycle. The reactor includes a pyrolysis chamber where the waste is heated to temperatures above 600 °C for primary pyrolysis. The volatile products (liquids, gases) are transported by a N 2 purge gas to a second chamber which contains a catalyst bed for cracking the tars at temperatures of about 1000-1100 °C. The tars are cracked into carbon and additional gases. Most of the deposited carbon is subsequently gasified by oxygenated volatiles (CO 2 , H 2 O) from the first stage. In a final step, the temperature of the first stage can be raised and the purge gas switched from N 2 to CO 2 and/or O 2 in order to gasify the remaining char in the first stage and the remaining carbon deposits in the second stage. Alternatively, the char can be removed from the first stage and saved as a future source of CO 2 or partially gasified to make activated carbon. This paper describes several improvements that were made in the original (First Generation) prototype pyrolyzer including: 1) replacement of stainless steel flanges with machineable ceramic in order to reduce weight; 2) construction of a new sample holder in order to make sample insertion and removal easier and sample heat-up more uniform; 3) replacement of a stainless steel outer shell with a double-wall quartz cylinder in order to significantly reduce weight and heat losses. In addition, experimental results are included for wheat straw and chicken manure feedstocks, primarily from the First Generation prototype.
Pyrolysis processing is one of several options for solid waste resource recovery in space. It has the advantage of being relatively simple and adaptable to a wide variety of feedstocks and it can produce several usable products from typical waste streams. The objective of this study is to produce a prototype mixed solid waste pyrolyzer for spacecraft applications. A two-stage reactor system was developed which can process about 1 kg of waste per cycle. The reactor includes a pyrolysis chamber where the waste is heated to temperatures above 600°C for primary pyrolysis. The volatile products (liquids, gases) are transported by a N 2 purge gas to a second chamber which contains a catalyst bed for cracking the tars at temperatures of about 1000 °C – 1100 °C. The tars are cracked into carbon and additional gases. Most of the carbon is subsequently gasified by oxygenated volatiles (CO 2 , H 2 O) from the first stage. In a final step, the temperature of the first stage can be raised and the purge gas switched from N 2 to CO 2 in order to gasify the remaining char in the first stage and the remaining carbon deposits in the second stage. Alternatively, the char can be removed from the first stage and saved as a future source of CO 2 or used to make activated carbon. The product gases from the pyrolyzer will be rich in CO and cannot be vented directly into the cabin. However, they can be processed in a shift reactor or sent to a high temperature fuel cell. A control system based on artificial neural networks (ANNs) is being developed for the reactor system. ANN models are well suited to describing the complicated relationships between the composition of the starting materials, the process conditions and the desired product yields.
Understanding the sustainable use of energy in various processes is an integral part of engineering and scientific studies, which rely on a sound knowledge of energy systems. Whilst many institutions now offer degrees in energy-related programs, a comprehensive textbook, which introduces and explains sustainable energy systems and can be used across engineering and scientific fields, has been lacking. Energy: Production, Conversion, Storage, Conservation, and Coupling provides the reader with a practical understanding of these five main topic areas of energy including 130 examples and over 600 practice problems. Each chapter contains a range of supporting figures, tables, thermodynamic diagrams and charts, while the Appendix supplies the reader with all the necessary data including the steam tables. This new textbook presents a clear introduction of basic vocabulary, properties, forms, sources, and balances of energy before advancing to the main topic areas of:
• Energy production and conversion in important physical, chemical, and biological processes,
• Conservation of energy and its impact on sustainability,
• Various forms of energy storage, and
• Energy coupling and bioenergetics in living systems.
A solution manual for the practice problems of the textbook is offered for the instructor. Energy: Production, Conversion, Storage, Conservation, and Coupling is a comprehensive source, study guide, and course supplement for both undergraduates and graduates across a range of engineering and scientific disciplines.
This paper continues previous work on pyrolysis processing of solid wastes for spacecraft and planetary surface applications. A domestic microwave oven was modified for use in this work for scoping studies in which the effects of sample composition, use of central microwave absorbers, and secondary pyrolysis of liquids were studied. Experiments were done with wheat straw and various formulations of a feces simulant. The microwave absorbers examined included activated carbon and char produced from previous experiments. The addition of a separate microwave-heated secondary pyrolysis zone was also examined as a means of reducing the liquid product yields. In general, the feces simulants had similar pyrolysis yields when compared to wheat straw for the char and total gas yields, but individual gas yields were different. For example, the feces simulants produced significantly more ethylene, larger amounts of methane, and smaller amounts of carbon oxides (CO + CO 2). This can be largely explained by the differences in elemental compositions. A comparison was also made of the microwave-assisted pyrolysis of feces simulants of variable moisture contents (0-60 wt. %). The higher moisture contents (40-60 wt. %) result in a delay for the onset of pyrolysis and a higher energy demand per gram of sample, as might be expected. However, at lower moisture contents, such as the 20 wt. % water for the baseline sample, it was found that the overall energy demand appeared to be lower than for the dried sample, perhaps due to the more efficient absorption of microwave energy.
Various technical and economic aspects relating to the briquetting of fine coal with sawdust have been evaluated with the results for two segments of that study presented here: binder and briquetting-parameter evaluations. Approximately 50 potential binder formulations were subjected to a series of screening evaluations to identify three formulations that were the most cost effective for briquetting fine coal with sawdust. Two of the binders, guar gum and wheat starch, were selected as most suitable for the pulverized coal market while the third formulation, lignosulfonate/lime, was targeted for the stoker market. Following binder selection, a number of briquetting parameters including binder and sawdust concentration, sawdust type, briquetting pressure and dwell time, coal and sawdust particle size, clay content, moisture content, and cure temperature and cure time were evaluated. Briquetting pressure and dwell time have the least impact while binder and sawdust concentrations, sawdust type, and curing conditions exerted the greatest influence on briquette quality.
In this study, we used a commercial pilot-scale pyrolysis reactor system to produce combustible gas and biochar at 620 °C from three sources (chicken litter, swine solids, mixture of swine solids with rye grass). Pyrolysis of swine solids produced gas with the greatest higher heating value (HHV) followed by the mixture of swine solids with rye grass and chicken litter. Relatively high S-containing gases were produced; dimethyl sulfide and methyl mercaptan concentrations were higher than the OSHA PEL limits. Biochar yield ranged from 43 to 49% based on dry weight with about 53% of carbon recovery. Whereas the HHV of the chicken litter biochar was slightly below that of low rank coals, swine-based biochars had HHVs between high and low rank coals. Approximately 50% of the feedstock energy was retained in biochar and 25% in produced gases. Manure biochars contained higher concentrations of P and K than that of original manure feedstocks. Consequently, these could be used as a low-grade fertilizer to improve soil fertility and crop yields. Extremely high energy (232.3 MJ/kg) was required to make 1 kg of biochar from wet swine manure with 97% MC. However, dewatering of the wet swine manure to 75% MC substantially reduced the external energy requirement by 19 folds. Mixing of dried biomass such as rye grass with the dewatered swine solids almost eliminated the need for external energy. If one can copyrolyze wet animal wastes with additional feedstock that are drier and more energy dense than rye grass such as waste plastic pellets, it may be possible to produce both valuable biochar and extra power.
Abstract The energy problems of the developing world are both serious and widespread. Lack of access to sufficient and sustainable supplies of energy affects as much as 90% of the population of many developing countries. Some 2 billion people are without electricity; a similar number remain dependent on fuels such as animal dung, crop residues, wood, and charcoal to cook their daily meals. Without efficient, clean energy, people are undermined in their efforts to engage effectively in productive activities or to improve their quality of life. Developing countries are facing two crucial-and related-problems in the energy sector. The first is the widespread inefficient production and use of traditional energy sources, such as fuelwood and agricultural residues, which pose economic, environmental, and health threats. The second is the highly uneven distribution and use of modern energy sources, such as electricity, petroleum products, and liquefied or compressed natural gas, which pose important issues of economics, equity, and quality of life. To address these problems, this paper evaluates some successful programs and recommends that governments support market-oriented approaches that make the energy market equally accessible and attractive to local investors, communities, and consumers. Such approaches ideally improve access to energy for rural and poor people by revising energy pricing and by making the first costs of the transition to modern and more sustainable uses of energy more affordable.
While pyrolysis of livestock manures generates nutrient-rich biochars with potential agronomic uses, studies are needed to clarify biochar properties across manure varieties under similar controlled conditions. This paper reports selected physicochemical results for five manure-based biochars pyrolyzed at 350 and 700°C: swine separated-solids; paved-feedlot manure; dairy manure; poultry litter; and turkey litter. Elemental and FTIR analyses of these alkaline biochars demonstrated variations and similarities in physicochemical characteristics. The FTIR spectra were similar for (1) turkey and poultry and (2) feedlot and dairy, but were distinct for swine biochars. Dairy biochars contained the greatest volatile matter, C, and energy content and lowest ash, N, and S contents. Swine biochars had the greatest P, N, and S contents alongside the lowest pH and EC values. Poultry litter biochars exhibited the greatest EC values. With the greatest ash contents, turkey litter biochars had the greatest biochar mass recoveries, whereas feedlot biochars demonstrated the lowest.
Several torrefaction experiments using wood briquettes are reported in this paper. The torrefied briquettes weight yield lies between 43 and 94 %, and energy yields ranged from 50 to 97 % depending on the operating parameters. After torrefaction the briquettes showed an increase of approximately 15 % in heating value, and a decrease of approximately 73 % in equilibrium moisture. It was shown that torrefied briquettes achieved hydrophobic character and remained unaffected when immersed in water. This research also provides information on proximate and elemental analysis, showing that temperature has more influence than residence time. The aforementioned data indicate that torrefaction is a feasible alternative to improve energy properties of ordinary briquettes and prevent moisture absorption during storage.
Direct research on gut microbiota for understanding its role as 'an important organ' in human individuals is difficult owing to its vast diversity and host specificity as well as ethical concerns. Transplantation of human gut microbiota into surrogate hosts can significantly facilitate the research of human gut ecology, metabolism and immunity but rodents-based model provides results with low relevance to humans. A new human flora-associated (HFA) piglet model was hereby established taking advantage of the high similarity between pigs and humans with respect to the anatomy, physiology and metabolism of the digestive system. Piglets were delivered via cesarean section into a SPF-level barrier system and were inoculated orally with a whole fecal suspension from one healthy 10-year-old boy. The establishment and composition of the intestinal microbiota of the HFA piglets were analyzed and compared with that of the human donor using enterobacterial repetitive intergenic consensus sequence-PCR fingerprinting-based community DNA hybridization, group-specific PCR-temperature gradient gel electrophoresis and real-time PCR. Molecular profiling demonstrated that transplantation of gut microbiota from a human to germfree piglets produced a donor-like microbial community with minimal individual variation. And the microbial succession with aging of those ex-germfree piglets was also similar to that observed in humans. This HFA model provides a significantly improved system for research on gut ecology in human metabolism, nutrition and drug discovery.
Carbothermally reduce a metal oxide to its corresponding metal nitride or metal carbide powder in a vertical gravity flow reactor by adding precursor pellets containing the metal oxide, a thermally decomposed binder material and carbon or a source of carbon directly to a heated reaction zone within the reactor. The pellets form a pellet bed, the top of which must be maintained within the heated reaction zone. The binder material is a blend of wheat and corn starches, optionally in conjunction with another binder such as melamine. The binder material thermally decomposes to a carbonaceous residue which functions both as an additional source of carbon and as a binder for the precursor pellets. The reactor may be modified by adding an internal vent line to remove volatile materials from the heated reaction zone before they have an opportunity to condense on internal reactor surfaces.
Handling and processing human feces in space habitats is a major concern and needs to be addressed for the Crew Exploration Vehicle (CEV) as well as for future exploration activities. In order to ensure crew health and safety, feces should either be isolated in a dried form to prevent microbial activity, or be processed to yield a non-biohazardous product using a reliable technology. During laboratory testing of new feces processing technologies, use of "real" feces can impede progress due to practical issues such as safety and handling thereby limiting experimental investigations. The availability of a non-hazardous simulant or analogue of feces can overcome this limitation. Use of a simulant can speed up research and ensure a safe laboratory environment. At Ames Research Center, we have undertaken the task of developing human fecal simulants. In field investigations, human feces show wide variations in their chemical/physical composition. However, under controlled experimental conditions using healthy adults (e.g. astronauts) fed a standard diet, the variations are likely to be minimal and within statistically acceptable levels. We have prepared a number of simulants using organic chemicals, soy paste ("Miso") and other materials - particularly those capable of representing the water-holding capacity (WHC) of feces. The chemical composition of this simulant was a better approximation to human feces than previously used analogues. Rheological studies of the simulant are planned to ensure that it simulates fecal material. The emphasis on rheology and WHC is based on the assumption that in space habitats feces will be compacted to reduce volume and/or the water will be removed to safen the fecal waste.
Char samples were obtained from slow pyrolysis of hazelnut and peanut shells at different temperatures (623 K, 873 K, and 1123 K). Composition, heating values, and surface properties of the charcoals were analyzed to explore their potentiality as bio-fuels and/or for further conversion into activated carbons. The chars generated from both wastes at 873 K exhibited good properties for these purposes, although the hazelnut shell-derived char showed a relatively greater potential. Furthermore, kinetics of the shell's pyrolysis over the temperature range 300 to 1200 K was characterized from nonisothermal thermogravimetric measurements by applying a model that assumes a steadily increasing variation in the activation energy with the process course. It allowed for a satisfactory description of kinetic data for the pyrolysis of hazelnut and peanut shells over the whole range of temperatures examined. Differences in the estimated kinetic parameters characterizing the wastes were found.
Batch isotherm experiments were conducted with chars to study adsorption of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Chars generated from corncobs, bamboo and wood chips in a laboratory pyrolyzer at 400-700 °C were compared with traditional kiln charcoals collected from villages in S/SE Asia and with activated carbons (ACs). 2,4-D uptake by laboratory chars obtained from bamboo and wood chips after 14 h of pyrolysis at 700 °C, from wood chips after 96 h of pyrolysis at 600 °C, and one of the field-collected chars (basudha) was comparable to ACs. H:C and O:C ratios declined with pyrolysis temperature and duration while surface area increased to >500 m(2)/g. Increasing pyrolysis intensity by increasing temperature and/or duration of heating was found to positively influence adsorption capacity yield (mg2,4-D/gfeedstock) over the range of conditions studied. Economic analysis showed that high temperature chars can be a cost-effective alternative to ACs for water treatment applications.
Recent au fost cercetate mai multe tipuri de biomasă, care pot produce
energie în vederea înlocuirii combustibililor fosili. Această lucrare prezintă o
abordare în vederea optimizării producţiei de bio-cocs din piroliza prin modificarea
parametrilor de proces. Materialul analizat a fost rumeguşul de cireş.
Experimentele s-au efectuat prin piroliza la temperaturi între 450 ºC şi 800 ºC.
Studiul experimental s-a bazat pe influenţa temeraturii, timpului de staţionare şi a
ratei de încălzire asupra producţiei de bio-cocs şi asupra determinării puterii
calorifice superioare a cocsului.
Recently much research has been investigated on identifying suitable
biomass species, which can provide high-energy outputs, to replace conventional
fossil fuels. This paper reports an approach for increasing the yield of bio-char
production from pyrolysis with respect to process conditions. The analyzed material
was cherry sawdust. The experiments were conducted for pyrolysis temperature
between 450ºC and 800ºC. The experimental study focused on the influence of
pyrolysis temperature, residence time or heating rate on the bio-char yield and on
determination of the HHV of the pyrolysis char.
Four physical properties have been identified as being of greatest value when developing or evaluating fuel briquette formulations or processes. They are resistances to crushing, impact, abrasion and water penetration. Arbitrary tests for these properties have evolved in this laboratory during a decade of investigations of binders and formulations for briquetting coal fines and the like. The simple test methods are described and some typical results are given.Tests of several types of commercial and pilot process fuel briquettes have been used to set realistic target values for these four physical properties. In the process development stages, it is suggested that the tests should relate to the briquette material, rather than the briquette as an entity, and that this can be achieved by transforming the raw data into various indices. These would allow intra-laboratory or inter-laboratory comparisons of briquette formulations. This approach is illustrated by presenting results for compressive strength, impact resistance and abrasion resistance. The same could apply to water resistance and some suggestions are discussed.The needs of research and development and of production in respect of briquette testing are seen as different, but complementary. It is hoped that the paper will stimulate researchers and producers alike to work towards the adoption of codes of standard practice in briquette testing.
We present a high temperature heat treatment study of CVD-grown graphene nanoribbons annealed up to 2800°C, demonstrating a progressive annihilation of lattice defects as the heat treatment temperature is raised. Starting at 1500°C, single and multiple loop formation were observed on the ribbons edges as the temperature was increased. The structural changes of the samples are documented by X-ray diffraction, Raman spectroscopy, TGA, SEM, and HRTEM. This work indicates that nanoribbon annealing eventually leads to defect-free samples, through graphitization and edge loop formation. The annealed material exhibits structural differences that could be tailored for a variety of specific applications.
Selected values of the heats of combustion and heats of formation of 719 organic compounds are reported here. The data tabulated pertain to compounds containing the elements carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (CHNOPS). The information is arranged according to classes of compounds and within each class, compounds are arranged by empirical formula. The general classes covered are: hydrocarbons, alcohols, phenols, polyols, ethers, aldehydes, ketones, acids, acid anhydrides, esters, steroids, lactones, carbohydrates, heterocyclic oxygen compounds, amines, amides, urea derivatives, guanidine derivatives, amino acids, peptides, alkaloids, heterocyclic nitrogen compounds, porphyrins, organic sulfur compounds, and organic phosphorus compounds. When a selection was made from among several investigators, commentary is provided to indicate the choice, and usually some relevant data. The number of references cited is 596. An alphabetical compound index is provided which gives the name, page number, empirical formula, and the Wiswesser Line Notation (WLN), for each compound.
Char samples were obtained from slow pyrolysis of hazelnut and peanut shells at different temperatures (623 K, 873 K, and 1123 K). Composition, heating values, and surface properties of the charcoals were analyzed to explore their potentiality as bio-fuels and/or for further conversion into activated carbons. The chars generated from both wastes at 873 K exhibited good properties for these purposes, although the hazelnut shell-derived char showed a relatively greater potential. Furthermore, kinetics of the shell’s pyrolysis over the temperature range 300 to 1200 K was characterized from nonisothermal thermogravimetric measurements by applying a model that assumes a steadily increasing variation in the activation energy with the process course. It allowed for a satisfactory description of kinetic data for the pyrolysis of hazelnut and peanut shells over the whole range of temperatures examined. Differences in the estimated kinetic parameters characterizing the wastes were found.
Progress towards the sanitation component of Millennium Development Goal (MDG) Target 7c was re-assessed to account for the need to protect communities and the wider population from exposure to human excreta. We classified connections to sewerage as 'improved sanitation' only if the sewage was treated before discharge to the environment. Sewerage connection data was available for 167 countries in 2010; of these, 77 had published data on sewage treatment prevalence. We developed an empirical model to estimate sewage treatment prevalence for 47 additional countries. We estimate that in 2010, 40% of the global population (2.8 billion people) used improved sanitation, as opposed to the estimate of 62% (4.3 billion people) from the WHO/UNICEF Joint Monitoring Programme (JMP), and that 4.1 billion people lacked access to an improved sanitation facility. Re-defining sewerage-without-treatment as 'unimproved sanitation' in MDG monitoring would raise the 1990 baseline population using unimproved sanitation from 53% to 64% and the corresponding 2015 target from 27% to 32%. At the current rate of progress, we estimate a shortfall of 28 percentage points (1.9 billion people) in 2010 and a projected 27 percentage point shortfall in 2015.
Modernized biomass gasification for power generation has attracted increasing interests as an attempt to reduce our reliance on fossil fuel. In fact, over the past couple of years, a lot of RD&D has gone into overcoming the technical hurdles of biomass gasification mainly producing clean gas which is free of particulates and tars bed agglomeration and biomass feeding/handling. Biomass Gasification Design Handbook offers engineers and scientist a "hands on" reference for understanding and successfully overcoming these hurdles. In this book, readers find a versatile resource that not only explains the basic principles of energy conversion and biomass conversion systems but also provides valuable insight into the design of biomass gasifiers. Thorough in his coverage, the author provides many worked out design problems, step-by-step design procedures, and real data on commercially operating systems. In addition, the book contains four valuable appendices that eliminate the need to search for essential information. Includes step-by-step design procedures and case studies for Biomass Gasification Provides worked process flow diagrams for gasifier design. Covers integration with other technologies (e.g. gas turbine, engine, fuel cells).
In this work, biomass samples were converted to char, liquid, and gaseous products using pyrolysis process at different temperatures. The amount of char from pyrolysis of the biomass samples decreases with increasing the pyrolysis temperature. The highest liquid yields were obtained from the biomass samples between 650 and 800 K. The yield of char and the chemical composition of char can be calculated as functions of the pyrolysis temperature. There have been numerous other mathematical equations, which were created based on data from the physical or chemical compositions, proximate or ultimate analysis of the biomass fuels. The char components and higher heating values (HHVs) of biomass fuels were correlated with pyrolysis temperatures. There were highly significant linear correlation between the pyrolysis temperature of the biomass fuel and the fixed carbon content and HHV of char. The fixed carbon (FC) and HHV (MJ/kg) of the char from biomass as a linear function of pyrolysis temperature (T, K) was calculated using the following equations: For Eqs. (a) and (b) the correlation coefficients (r) were 0.9809 and 0.9983, respectively.
A sustainable energy system includes energy efficiency, energy reliability, energy flexibility, fuel poverty, and environmental impacts. A sustainable biofuel has two favorable properties which are availability from renewable raw material, and its lower negative environmental impact than that of fossil fuels. Charcoal is produced by slow heating wood (carbonization) in airtight ovens or retorts, in chambers with various gases, or in kilns supplied with limited and controlled amounts of air. The charcoal yield decreased gradually from 42.6 to 30.7% for the hazelnut shell and from 35.6 to 22.7% for the beech wood with an increase of temperature from 550 to 1,150 K while the charcoal yield from the lignin content decreased sharply from 42.5 to 21.7% until it was at 850 K during the carbonization procedures. The charcoal yield decreases as the temperature increases. The ignition temperature of charcoal increases as the carbonization temperature increases. The charcoal briquettes that are sold on the commercial market are typically made from a binder and filler.
Char is ubiquitous in the environment and contributes significantly to the inert soil organic carbon pool.
Its roles as a carbon sink and a strong sorbent of organic contaminants have come under increasing attention. However, quantifying these roles is difficult because properties such as degradability and sorption affinity vary greatly amongst chars, especially those produced at different temperatures. Here we
describe a simple method for gauging the degree of aromatic condensation of chars, a molecular-scale
property that affects both their degradability and sorption affinity. The method involves adding 13C6 benzene directly to char. The 13C nuclear magnetic resonance (NMR) chemical shift of the sorbed benzene is affected by diamagnetic ring currents in the fused aromatic structures in the char. These ring currents increase in magnitude with increasing extent of aromatic condensation. Seventeen heat-treated materials were analysed in this way. Our results confirm that aromatic condensation increases with increasing heat treatment temperature (HTT) and that activated chars contain the most highly condensed aromatic structures, but also show the importance of starting material and heat treatment time on aromatic condensation. We also show for four of the materials that the ring current effect on chemical shift was similar for other 13C-labelled molecules, including MeOH, CH3CN and toluene.
Biomass as a fuel suffers from its bulky, fibrous, high moisture content and low-energy-density nature, leading to key issues including high transport cost and poor biomass grindability. This study investigates the possibility to pretreat biomass to produce biochar as a solid biofuel to address these issues. Biochars were produced from the pyrolysis of centimeter-sized particles of Western Australia (WA) mallee wood in a fixed-bed reactor at 300 to 500 °C and a heating rate of 10 °C/min. The data show that, at pyrolysis temperatures ≥320 °C, biochar as a fuel has similar fuel H/C and O/C ratios compared to Collie coal that is the only coal being mined in WA. Converting biomass to biochar leads to a substantial increase in fuel mass energy density from 10 GJ/ton of green biomass to 28 GJ/ton of biochars prepared from pyrolysis at 320 °C, in comparison to 26 GJ/ton for Collie coal. However, there is little improvement in fuel volumetric energy density, which is around 7−9 GJ/m3 in comparison to 17 GJ/m3 of Collie coal. Biochars are still bulky and grinding is required for volumetric energy densification. Biochar grindability experiments show that the fuel grindability increases drastically even at pyrolysis temperature as low as 300 °C. Further increase in pyrolysis temperature to 500 °C leads to only a small increase in biochar grindability. Under the grinding conditions, a significant size reduction (34−66% cumulative volumetric size below 75 μm) for biochars can be achieved after 4 minutes grinding (in comparison to only 19% for biomass after 15 minutes grinding), leading to a significant increase in volumetric energy density (e.g., from 8 to 19 GJ/m3 for biochar prepared from pyrolysis at 400 °C). Whereas grinding raw biomass typically results in large and fibrous particles, grinding biochars produces short and round particles. The results in this article indicate that biochar has desired fuel properties and potentially a good solution to address the key issues including high transport cost and poor grindability associated with the direct use of biomass as a fuel.
Two types of swine-manure chars, hydrothermally produced hydrochar and slow-pyrolysis pyrochar, and their raw swine-manure solid were characterized using advanced solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. In comparison to raw swine-manure solid, both hydrochars and pyrochar displayed significantly different structural features, with lower alkyl carbons, NCH, OCH3, O-alkyl, and COO/N−C═O groups but higher aromatic/olefinic and aromatic C−O groups. The chemical structures of four hydrochars varied with different processing conditions. In comparison to the hydrochar with only water wash (HTC-swine W), washing hydrochar with acetone (HTC-swine A) removed the soluble intermediates deposited on the hydrochar, as shown by the decrease of O-alkyl (primarily carbohydrates), corresponding increase of aromatic/olefinic carbons and complete removal of OCH3 groups. With citric acid prewash and acetone wash (HTC-AW-swine A), aromatic C−O and aromatics/olefinics were increased and alkyls were decreased, with O-alkyls totally removed in comparison to just acetone wash (HTC-swine A). Citric acid catalysis and acetone wash (HTC-AC-swine A) increased aromatic C−O and non-protonated aromatics/olefinics, decreased alkyls further, and reduced protonated aromatics/olefinics compared to citric acid prewash and acetone wash (HTC-AW-swine A). The ratios of non-protonated to protonated aromatic/olefinic carbons for HTC-swine W, HTC-swine A, and HTC-AW-swine A hydrochars were quite similar but enhanced for HTC-AC-swine A hydrochar. Obviously, citric acid catalysis and acetone wash (HTC-AC-swine A) provided deeper carbonization than other hydrothermal processes. Hydrothermal carbonization (HTC) processes were associated with the hydrolysis and subsequent decomposition of major biopolymer components in swine manure. The increase of aromaticity during HTC was likely due to condensation polymerization of the intermediates from the degradation of carbohydrates. Pyrochar produced from slow pyrolysis was structurally different from HTC hydrochars. The dominant component of pyrochar was aromatics, whereas that of hydrochars was alkyl moieties. The aromatic cluster size of pyrochar was larger than those of hydrochars. Slow pyrolysis at 620 °C provided deeper carbonization than HTC processes.
Coal briquettes and the binders were tested from the view of resistivity to transportation, loading and storage by measuring
the abrasion index and strength to crushing. The binders used in coal briquetting also affect the combustion properties of
the coal. Combustion properties of the Tuncbilek lignite and different binders were analysed by thermogravimetric (TG/DTG)
methods. Molasses, carboxyl methylcellulose (CMC), sulphide liquor, heavy crude oil, sodium silicate, cornstarch, lime, peridur,
and bentonite, cement poly(vinyl acetate) were used as binders. It was observed that molasses and CMC decreased the residue
content at the end of the combustion period, whereas, heavy crude oil, sulphide liquor and corn starch increased the calorific
values of the samples.
Diplicate groups of rainbow trout were fed low-protein (38%) diets containing high levels (38%) of five different carbohydrate sources (raw starch, extruded corn, extruded wheat, extruded corn starch or extruded wheat starch). A modified pair-feeding method was used to allow equal intakes of protein and of digestible energy by each group of fish. Growth parameters were followed over a period of 18 weeks; the digestibility of the diets, nitrogen and energy balances, and the respiratory and ammonia quotients of fish fed the different diets were determined. To study the long-term effects of dietary carbohydrates, plasma glucose profile and its control by bovine insulin was followed in fish fed over 30 weeks with selected test diets. The results show that inclusion of extruded cereals or extruded starch improves availability of dietary energy. High levels of carbohydrates to not adversely affect overall growth or nutrient retention efficiencies. Long-term feeding with carbohydrate-rich d diets does not confer on trout any adaptive capacity to regulate postprandial glycemia levels. Respirometric measurements appear to provide interesting data on the metabolic utilization of body substrates.
Fuelwood shortages are widespread throughout the developing world. One option to alleviate the situation is to substitute indigenously produced coal briquettes. This paper reviews carbonizing and briquetting technologies that convert coal to a smokeless, strong, and low-emissions bbriquette for domestic or commercial application. Cost studies are presented indicating the briquettes are competitive in some countries. We examine experiences with briquettes in the Third World and identify 36 countries where both coal and fuelwood shortages exist, which are prerequisites for the technology Finally, we describe the necessary resource, technological, market, and government policy assessments for analysing a country's coal briquetting prospects.
In Arizona, cotton (Gossypium) plant residue left in the field following harvest must be buried to prevent it from serving as an overwintering site for insects such as the pink bollworm. Most tillage operations employed to incorporate the residue into the soil are energy intensive and often degrade soil structure. Trials showed that cotton plant residue could be incorporated with pecan shells to produce commercially acceptable briquettes. Pecan shell briquettes containing cotton residue rather than waste paper were slightly less durable, when made using equivalent weight mixtures and moisture contents. Proximate and ultimate analyses showed the only difference among briquette samples to be a higher ash content in those made using cotton plant residue. Briquettes made with paper demonstrated longer flame out time, and lower ash percentage, compared to those made with cotton plant residue.
This article deals with slow pyrolysis of four shells such as hazelnut, walnut, almond and sunflower at the range of temperature 500–1200 K in a cylindrical reactor batch reactor. The aim of this work was to experimentally investigate how the temperature affects char, liquid and gaseous product yields from different shells via pyrolysis. The amount of char from pyrolysis of the shell samples decreases with increasing the pyrolysis temperature. The highest liquid yields were obtained from the samples between 650 and 800 K. The yield and the chemical composition of char can be calculated as functions of the pyrolysis temperature. The char components and higher heating values (HHVs) of shell fuels were correlated with pyrolysis temperatures. There were highly significant linear correlation between the pyrolysis temperature of the fuel and the fixed carbon content and HHV of char.
A unified correlation for computation of higher heating value (HHV) from elemental analysis of fuels is proposed in this paper. This correlation has been derived using 225 data points and validated for additional 50 data points. The entire spectrum of fuels ranging from gaseous, liquid, coals, biomass material, char to residue-derived fuels has been considered in derivation of present correlation. The validity of this correlation has been established for fuels having wide range of elemental composition, i.e. C — 0.00–92.25%, H — 0.43–25.15%, O — 0.00–50.00%, N — 0.00–5.60%, S — 0.00–94.08% and Ash — 0.00–71.4%. The correlation offers an average absolute error of 1.45% and bias error as 0.00% and thereby establishes its versatility. Complete details of few salient data points, the methodology used for derivation of the correlation and the base assumptions made for derivation are the important constituents of this work. A summary of published correlations along with their basis also forms an important component of present work.
Although some questions remain, biochar shows potential for carbon storage and energy production and as a soil additive.
The use of coal briquettes and improved stoves by Chinese households has been encouraged by the government as a means of reducing air pollution and health impacts. In this study we have shown that these two improvements also relate to climate change. Our experimental measurements indicate that if all coal were burned as briquettes in improved stoves, particulate matter (PM), organic carbon (OC), and black carbon (BC) could be annually reduced by 63 +/- 12%, 61 +/- 10%, and 98 +/- 1.7%, respectively. Also, the ratio of BC to OC (BC/OC) could be reduced by about 97%, from 0.49 to 0.016, which would make the primary emissions of household coal combustion more optically scattering. Therefore, it is suggested that the government consider the possibility of: (i) phasing out direct burning of bituminous raw-coal-chunks in households; (ii) phasing out simple stoves in households; and, (iii) financially supporting the research, production, and popularization of improved stoves and efficient coal briquettes. These actions may have considerable environmental benefits by reducing emissions and mitigating some of the impacts of household coal burning on the climate. International cooperation is required both technologically and financially to accelerate the emission reduction in the world.