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Environmental impacts of valorisation of crude glycerol from biodiesel production - A life cycle perspective
... consecuente reducción en los precios de venta, lo cual a su vez afecta la economía del proceso de producción de biodiésel (Kumawat et al., 2024;Sandid et al., 2024). Con la finalidad de reducir las grandes cantidades de glicerol producidas, se han buscado alternativas para el uso de este subproducto (Tomatis et al., 2024). Entre los usos directos del glicerol crudo (de baja pureza) se incluyen su combustión directa para la generación de calor y energía; y su utilización como alimento de rumiantes debido a su aporte energético (Zacaroni et al., 2022;Zhang et al., 2022). ...
... Por otra parte, el glicerol crudo contiene principalmente glicerol y agua, junto con pequeñas cantidades de catalizador, metanol y ésteres metílicos de ácidos grasos en diferentes proporciones (Bansod et al., 2024;Tomatis et al., 2024). Por ello, es necesario remover las impurezas presentes en el glicerol crudo con la finalidad de utilizarse en las industrias de alimentos, farmacéutica, cosméticos y tabaco. ...
El glicerol se puede obtener a partir en los procesos de producción de biodiésel, en constante aumento. Como ejemplo, la producción mundial de biodiésel en 2021 generó más de 4.5 billones de litros de glicerol. Debido al exceso en el volumen de glicerol producido, se le ha llegado a considerar como un inconveniente financiero y medioambiental para la industria del biodiésel, surgiendo la necesidad de buscar alternativas para aprovechar el glicerol como una fuente renovable para la obtención de productos químicos que representen un considerable beneficio económico. Por otra parte, México cuenta con un gran potencial para producir biodiésel a partir de aceites de palma africana, higuerilla y Jatropha, estimándose un potencial de producción de hasta 368 millones de litros de biodiésel para el año 2030. Por ello, en este artículo se presentan algunos de los retos y oportunidades que ofrece la valorización del glicerol en México, un país que busca impulsar el uso de biocombustibles y desarrollar una industria química verde y sustentable.
... With recent expansions in global biodiesel production, there has been an excess of crude glycerol which is typically classified as waste. Consequently, various approaches for its utilization are currently under investigation [3]. Currently, 1 ton of glycerol is generated for every 10 tons of biodiesel produced. ...
... All the samples show Ni and CeO 2 phases, and crystalline phases associated with cerium carbonates Ce 2 O(CO 3 ) 2 H 2 O (JCPDS card No. 044-0617) and Ce(OH)CO 3 (JCPDS card No. 032-0189). CO 2 is a by-product of the APH process, thus leading to the formation of CO 3 2− ions in aqueous media. Cerium-derived ions can exist [Ce(H 2 O) n 3+ ] in aqueous media [44,45]. ...
The aqueous-phase hydrogenolysis of glycerol was studied in Ni/CeO2 catalytic systems prepared by incipient wetness impregnation. The operating conditions were 34 bar, 227 ºC, 5 wt.% of glycerol, and a W/mglycerol = 20 g catalyst min/g glycerol without a hydrogen supply. The effect of the catalyst preparation conditions on the catalytic activity and physicochemical properties of the catalysts was assessed, particularly the calcination temperature of the support, the calcination temperature of the catalyst, and the Ni content. The physicochemical properties of the catalysts were determined by N2 adsorption, H2-TPR, NH3-TPD, and XRD, among other techniques. A relevant increase in acidity was observed when increasing the nickel content up to 20 wt.%. The increase in the calcination temperatures of the supports and catalysts showed a detrimental effect on the specific surface area and acid properties of the catalysts, which were crucial to the selectivity of the reaction. These catalysts notably enhanced the yield of liquid products, achieving global glycerol conversion values ranging from 17.1 to 29.0% and carbon yield to liquids ranging from 12.6 to 24.0%. Acetol and 1,2-propanediol were the most abundant products obtained in the liquid stream.
... A key challenge in using crude glycerol for industrial fermentation is the inhibitory effect caused by impurities, as noted by S. Mehariya et al. (2023). After transesterification, glycerol typically contains varying concentrations of methanol (a residue from the methylation process in biodiesel production), sulphate or chloride salts, residual free fatty acids, fatty acid methyl esters, and soap -by-products of the hydroxide catalyst used in transesterification, as described by M. Tomatis et al. (2024). One approach to mitigating this inhibitory effect, as demonstrated by Y. Wang et al. (2024), is the purification of crude glycerol, though this significantly increases substrate cost. ...
Glycerol is a natural polyol formed as a major by-product during biodiesel production. The use of glycerol, which is uniquely utilised by Clostridium pasteurianum, for butanol production is highly promising but requires a thorough understanding and optimisation of the process. This study aimed to determine the composition of crude glycerol and evaluate its suitability as a substrate for butanol accumulation by Clostridium sp. UCM B-7570. During the research, a chromatographic method was used to determine the composition of crude glycerol and the solvent content in the culture liquid. An experimental approach was employed according to a developed scheme, incorporating microbiological methods (microorganism cultivation), biotechnological methods (strain cultivation under conditions resembling industrial settings, investigation of the solvent accumulation), and statistical methods for the mathematical processing of research results. A detailed study of the composition of different crude glycerol fractions showed that the initial glycerol layer contained a relatively low proportion of glycerol itself. The identified components accounted for more than half of the mass of the glycerol layer (51.6%). It was shown that the glycerol layer was found to contain only up to 20% glycerol and approximately 17% methanol, which is an inhibitor of microbial growth and development. It was determined that the highest butanol accumulation (9 g/L) occurred at a crude glycerol concentration of 35 g/L, while culture development was inhibited at 45 g/L. During the initial phase of fed‑batch cultivation of Clostridium sp. UCM B-7570, butanol accumulation remained unchanged. However, the subsequent fermentation of crude glycerol led to a twofold reduction in solvent by accumulation, ultimately resulting in complete inhibition of production by the eighth period, possibly due to the presence of methyl esters in the medium. To enhance butanol production technology, the use of sorbents such as activated carbon during fermentation is recommended. This study provides practical insights for biotechnologists and the demonstrated ability of Clostridium sp. UCM B-7570 to ferment crude glycerol for butanol production presents numerous research opportunities. These findings contribute to improving the feasibility of biobutanol production and advancing biomass-based industrial processes as viable alternatives to petroleum-derived products
... Glycerol is a by-product produced on a large scale in the biodiesel industry, 1 kg of glycerol for every 10 kg of biodiesel produced (Amari et al., 2023;Laura et al., 2020;Nda-Umar et al., 2018;Rodrigues et al., 2019;Tomatis et al., 2024). Pure glycerol is a non-toxic, edible, biosustainable, and biodegradable compound with interesting physical and chemical properties: low volatility, hygroscopicity, plasticizing effect, promotion of softness and flexibility, solvent power and solubility, high miscibility, chemical stability, high viscosity, antifreeze properties, emollient, bodying and sweetening agent (Ishak et al., 2016;Quispe et al., 2013). ...
Glycerol is produced on a large scale as a byproduct in the biodiesel market. In order to give an application to glycerol, this work uses diglycerol from synthesized polyglycerol and commercial triglycerol in the synthesis of long chain esters obtained from esterification and transesterification reactions with oleic acid, methyl oleate, and epoxidized methyl oleate. Diglycerol tetraoleate (DGMO), epoxidized diglycerol tetraoleate (DGEMO), and triglycerol pentaoleate (TGOA) were synthesized and characterized by ¹ H and ¹³ C Nuclear Magnetic Resonance (NMR) and infrared (IR) spectroscopy. Polyglycerol esters were evaluated for basic lubrication properties such as density, kinematic viscosity, viscosity index, melting point, and thermo‐oxidative stability. The ester that showed best thermo‐oxidative stability was DGEMO. In addition, the influence of esters synthesized as additives in a pure paraffinic oil lubricant was evaluated and the TGOA showed greater change in viscosity at 100 and 40°C and in melting point which was increased by 1.56°C.
When recycling is beneficial for the environment, results from a life cycle assessment (LCA) should give incentives to collection for recycling and also to the use of recycled material in new products. Many approaches for modeling recycling in LCA assign part of the environmental benefits of recycling to the product where the recycled material is used. For example, the Circular Footprint Formula in the framework for Product Environmental Footprints (PEF) assigns less than 45% of the benefits of recycling to a polymer product sent to recycling. Our calculations indicate that this creates an incorrect climate incentive for incineration of renewable LDPE, when the recovered energy substitutes energy sources with 100–300% more climate impact than the Swedish average district heat and electricity.
The risk of incorrect incentives can be reduced through allocating part of the net benefits of energy recovery to the life cycle where the energy is used; we propose this part can be 60% for Sweden, but probably less in countries without a district-heating network. Alternatively, the LCA can include the alternative treatment of waste that is displaced at the incinerator by waste from the investigated product.
These solutions both make the LCA more balanced and consistent. The allocation factor 0.6 at incineration almost eliminates the risk of incorrect incentives in a PEF of renewable polymers. However, the focus of LCA on one product at a time might still make it insufficient to guide recycling, which requires concerted actions between actors in different life cycles.
This simulation-based comparative assessment aims to quantify the environmental and human-health impacts of greener hydrogen (H2) production via three glycerol-based technologies, including: supercritical water reforming (SCWR), aqueous-phase reforming (APR) and autothermal reforming (ATR). The GaBi (2018 edition) life-cycle assessment (LCA) platform is used to develop cradle-to-gate product system models for these technologies and the TRACI 2.1 methodology is used to quantify their midpoint impact categories. Aspen HYSYS (v11) process-simulation software is used to generate the life-cycle inventory (LCI) primary data required to produce 1 kg of H2 via each of the indicated glycerol-reforming technologies. Per ISO 14040:2006 reporting requirements for the LCA results interpretation step, three base case (BC) scenarios and four sensitivity scenarios (SS) are developed and quantified to compare the effects of different process electricity sources (US grid mix versus wind power) and thermal energy sources (natural gas versus biogas) on the LCA results. The high operating pressure (viz. 240 bar) of SCWR enabled assessment of the impact of in situ electricity generation to offset some of electricity required for this technology. The major insights from this research are as follows: (i) per 1 kg of produced H2, APR reduces CO2 emissions by ≈95% compared to ATR and by ≈92% compared to SCWR, (ii) for BC scenarios, the primary energy consumption (in MJ/kg of produced H2) is in the following order from highest to lowest: ATR > SCWR > APR and (iii) H2 production via glycerol APR is more environmentally sustainable than SCWR and ATR, and thus offers a promising path for greener H2 production. Future environmental sustainability studies should focus on expanding the scope of this study to include H2 production via water electrolysis using renewable electricity sources and via solar and nuclear-driven thermochemical water splitting.
Global issues such as environmental problems and food security are currently of concern to all of us. Circular bioeconomy is a promising approach towards resolving these global issues. The production of bioenergy and biomaterials can sustain the energy–environment nexus as well as substitute the devoid of petroleum as the production feedstock, thereby contributing to a cleaner and low carbon environment. In addition, assimilation of waste into bioprocesses for the production of useful products and metabolites lead towards a sustainable circular bioeconomy. This review aims to highlight the waste biorefinery as a sustainable bio-based circular economy, and, therefore, promoting a greener environment. Several case studies on the bioprocesses utilising waste for biopolymers and bio-lipids production as well as bioprocesses incorporated with wastewater treatment are well discussed. The strategy of waste biorefinery integrated with circular bioeconomy in the perspectives of unravelling the global issues can help to tackle carbon management and greenhouse gas emissions. A waste biorefinery–circular bioeconomy strategy represents a low carbon economy by reducing greenhouse gases footprint, and holds great prospects for a sustainable and greener world.
The agro-food industry generates large amounts of waste that contribute to environmental contamination. Animal fat waste constitutes some of the most relevant waste and the treatment of such waste is quite costly because environmental regulations are quite strict. Part of such costs might be reduced through the generation of bioenergy. Biodiesel constitutes a valid renewable source of energy because it is biodegradable, non-toxic and has a good combustion emission profile and can be blended up to 20% with fossil diesel for its use in many countries. Furthermore, up to 70% of the total cost of biodiesel majorly depends on the cost of the raw materials used, which can be reduced using animal fat waste because they are cheaper than vegetable oil waste. In fact, 6% of total feedstock corresponded to animal fat in 2019. Transesterification with alkaline catalysis is still preferred at industrial plants producing biodiesel. Recent developments in heterogeneous catalysts that can be easily recovered, regenerated and reused, as well as immobilized lipases with increased stability and resistance to alcohol denaturation, are promising for future industrial use. This manuscript reviews the available processes and recent advances for biodiesel generation from animal fat waste.
This study investigated the purification of glycerol obtained from the biodiesel production process using various solvents including toluene, petroleum ether, and n-butanol in a micro-scale extractor. Glycerol was produced using a mixture of soybean oil and methanol in a molar ratio of 6:1 in the presence of potassium hydroxide catalyst at 60 °C during 4h; it was then neutralized by sulfuric acid 98%. The produced crude glycerol was extracted in different solvents using a microreactor with a T-shaped mixer with a square cross-section dimension of 0.9 mm. Operating temperatures were 303.15K and 318.15K and the solvent to feed ratio were 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, and 4:1. Based on the results, petroleum ether was more effective in removing methanol from glycerol and purifying it, as compared with the other two solvents. The highest level of glycerol purity which was obtained through using toluene, petroleum ether, and n-butanol solvents was 93.6, 98.4, and 83.4%, respectively. These values were obtained at 318.15K.
PurposeDue to increasing environmental concerns about petroleum-based products, the replacement of petro-products has attracted much attention in recent years. The purpose of this paper was to evaluate the potential environmental impacts of glycerol-based structural bio-adhesive produced through the reversible addition-fragmentation chain transfer polymerization process.Methods
In this study, two pathways of glycerol production were considered in this cradle-to-gate life cycle assessment: bio-glycerol produced from biodiesel production plant and petroleum-based glycerol derived from petroleum refineries. Several impact categories were analyzed including global warming potential, acidification potential, eutrophication potential, and human health effects (both cancer and non-cancer). The impact of different allocation methods (energy content, mass value, and economic value) was also explored in this study.ResultsOur results showed that bio-glycerol-based structural adhesive had a lower environmental impact in general compared to petro-glycerol-based structural adhesive. Higher environmental impacts throughout the structural bio-adhesive life cycle were observed by adopting the energy allocation method. The key factors that influence the global warming potential were electricity sources and the product yield.Conclusions
This LCA study provides useful information for developing sustainable biomaterials and processes. It is recommended to further explore the potential approaches to reduce the carbon intensity and eutrophication potential in the RAFT polymerization process as it is identified as the hotspot in the structural bio-adhesive production process.
Crude glycerol (CG) is a by-product formed during the trans-esterification reaction for biodiesel production. Although crude glycerol is considered a waste stream of the biodiesel industry, it can replace expensive carbon substrates required for lipid production by oleaginous micro-organisms. However, crude glycerol has several impurities, such as methanol, soap, triglycerides, fatty acids, salts and metals, which are created during the trans-esterification process and may affect the cellular metabolism involved in lipid synthesis. This review aims to critically present a variation in crude glycerol composition depending on trans-esterification process and impact of impurities present in the crude glycerol on the cell growth and lipid accumulation by oleaginous microbes. This study also draws comparison between purified and crude glycerol for lipid production. Several techniques for crude glycerol purification (chemical treatment, thermal treatment, membrane technology, ion-exchange chromatography and adsorption) have been presented and discussed with reference to cost and environmental effects.
Glycerol is produced as a by-product of the transesterification of vegetable oils and fats with methanol in the presence of a suitable catalyst (Biodiesel Production Process). In this study, the economic and environmental impacts of crude glycerol purification processes (i.e. vacuum distillation and membrane separation) are studied and compared. Aspen Plus v. 8.2 is employed to obtain mass and energy balance for crude glycerol purification processes. Based on the study, it is concluded that the processes are economically profitable, when the selling price of the purified glycerol is $ 1.98/kg. Membrane process is more profitable as compared to the vacuum distillation and has less environmental impact.
Production of liquid biofuels derived from vegetable oils in recent years significantly increased which causes surplus of by-product (waste glycerol) from this process. Therefore it is of great importance to find cheap and fast method of use its utilization. In this study, a possibility of the utilization of technical purity glycerin as an addition to wood pellets intended for heating purposes has been investigated. Usefulness of pellets contained glycerol additions has been compared in terms of applicable quality standards for wood pellets. Effects of waste glycerol addition on concentration of combustion products as well as temperature in heat exchanger have also been examined. The experimental results show that co-combustion of waste glycerol with wood sawdust does not worsen heating efficiency in a standard boiler. Moreover, 4.5 and 7% presence of glycerol in wood pellets correlated to a nearly twofold decrease of NOx concentration in flue gas. Therefore, the use of the waste glycerol as a binder for the production of pellets can be a simple and cost-effective solution of its utilization.
Glycerol represents an emerging renewable bio-derived feedstock, which could be used as a source for producing hydrogen through steam reforming reaction. In this review, the state-of-the-art about glycerol production processes is reviewed, with particular focus on glycerol reforming reactions and on the main catalysts under development. Furthermore, the use of membrane catalytic reactors instead of conventional reactors for steam reforming is discussed. Finally, the review describes the utilization of the Pd-based membrane reactor technology, pointing out the ability of these alternative fuel processors to simultaneously extract high purity hydrogen and enhance the whole performances of the reaction system in terms of glycerol conversion and hydrogen yield.
PurposeLife cycle impact assessment (LCIA) translates emissions and resource extractions into a limited number of environmental impact scores by means of so-called characterisation factors. There are two mainstream ways to derive characterisation factors, i.e. at midpoint level and at endpoint level. To further progress LCIA method development, we updated the ReCiPe2008 method to its version of 2016. This paper provides an overview of the key elements of the ReCiPe2016 method. Methods
We implemented human health, ecosystem quality and resource scarcity as three areas of protection. Endpoint characterisation factors, directly related to the areas of protection, were derived from midpoint characterisation factors with a constant mid-to-endpoint factor per impact category. We included 17 midpoint impact categories. Results and discussionThe update of ReCiPe provides characterisation factors that are representative for the global scale instead of the European scale, while maintaining the possibility for a number of impact categories to implement characterisation factors at a country and continental scale. We also expanded the number of environmental interventions and added impacts of water use on human health, impacts of water use and climate change on freshwater ecosystems and impacts of water use and tropospheric ozone formation on terrestrial ecosystems as novel damage pathways. Although significant effort has been put into the update of ReCiPe, there is still major improvement potential in the way impact pathways are modelled. Further improvements relate to a regionalisation of more impact categories, moving from local to global species extinction and adding more impact pathways. Conclusions
Life cycle impact assessment is a fast evolving field of research. ReCiPe2016 provides a state-of-the-art method to convert life cycle inventories to a limited number of life cycle impact scores on midpoint and endpoint level.
Biodiesel is obtained by the process of transesterification of vegetable oils and animal fats and crude glycerol is the main by-product of the biodiesel manufacturing chain. As a result glycerol production has rapidly increased in the last decades. This work focuses on the development and the validation of a process to convert biodiesel-derived glycerol into a fuel for internal combustion engines. In order to obtain a higher conversion efficiency it was necessary to convert crude glycerol to tert-butyl ethers by means of an etherification process that was carried out in the laboratory. Then the obtained glycol-ethers mixture (GEM) was blended with a commercial diesel fuel to improve its thermal efficiency. In this paper a life cycle analysis for these GEM/diesel blends was carried out using a Life Cycle Assessment (LCA) methodology, in order to evaluate the environmental impacts of these new oxy-fuels; from GEM production to GEM use as an additive for diesel fuel. The LCA results highlight that the use of these new oxy-fuels in diesel engines can lead to an effective reduction in terms of greenhouse gases emissions throughout the entire life cycle.
The purification of raw glycerin in biodiesel production can provide economic benefits and help to avoid residue accumulation, thus reducing environmental impacts. In this work, the glycerin obtained from biodiesel production by catalytic transesterification of waste cooking oil was purified by sequential extraction with organic solvents, followed by discoloration with activated coal and monitoring by 1 H NMR spectroscopy. Through sequential extraction with petroleum ether and toluene, in that order, followed by discoloration with activated carbon, 99.2% pure glycerin was obtained. This technique is shown to allow for glycerin purification using less drastic or hazardous conditions than those commonly applied in vacuum distillation.
Recently, lactic acid has emerged as one of the most relevant platform molecules for the preparation of bio-chemicals. Due to the limited productivity of sugar fermentation, the dominant industrial technology practiced for its manufacture, new chemocatalytic processes are being developed in order to meet the expected demand for this intermediate. The Lewis-acid catalysed isomerisation of dihydroxyacetone has attracted particular interest. If the reaction is performed in water, lactic acid is attained directly, while if alcohols are used as the solvent the desired product can be obtained upon subsequent hydrolysis of the alkyl lactates formed. Herein, we (i) demonstrate tin-containing MFI zeolites prepared by scalable methods as highly active, selective and recyclable catalysts able to operate in concentrated dihydroxyacetone aqueous and methanolic solutions, and (ii) reveal by life cycle analysis that a process comprising the enzymatic production of dihydroxyacetone from crude glycerol and its chemocatalytic isomerisation in methanol is more advantageous compared to glucose fermentation in terms of both sustainability and operating costs for the production of lactic acid. In particular, we uncover that the reduced energy requirements and CO2 emissions of the cascade process originate from the valorisation of a waste feedstock and from the high performance and recyclability of the inorganic catalyst and that the economic advantage is strongly determined by the comparably low market price of glycerol.
This review provides a summary of the research conducted on the use of crude glycerol, the major byproduct of the biodiesel industry, as substrate for anaerobic co-digestion and production of biogas. In general, for every 100 kg biodiesel produced, approximately 10 kg crude glycerol is generated. Because this glycerol is expensive to purify for use in food, pharmaceutical, or cosmetic industries, biodiesel producers must seek alternative methods for its disposal. Several studies have demonstrated that the use of crude glycerol as a C source for fermentation and biogas generation is a promising alternative use for this waste material. The high C content of glycerol increases the C:N ratio in the mixture, avoiding the inhibition of the process by the excess of N increasing methane production of digesters by 50 to 200%. Anaerobic codigestion of glycerol and a variety of residual biomasses may be a good integrated solution for managing these wastes and simultaneously producing a source of bioenergy in an environmentally friendly way. On the other hand, after anaerobic treatment of glycerol, an organic matter-rich solid waste is generated (digestate). The incorporation of digestates from glycerol co-digestion to soils constitutes an important source of organic matter and nutrients for plants. However, the potential of digestates as an organic soil amendment has not been sufficiently studied. The utilization of glycerol as a potential source of energy, rather than as a waste, seems to be a convenient way of lowering the costs of biodiesel production and making this emerging industry more competitive.
Glycerol is an important bio-platform molecule, potentially usable for the synthesis of various chemicals and fuel additives, the synthesis of acrolein by dehydration being one of the most studied reactions. Through the application of Life Cycle Assessment (LCA) methodology we investigated the production of acrolein from glycerol, by comparing two alternative scenarios in which glycerol is obtained as a co-product either in triglyceride trans-esterification to FAME or in hydrolysis to fatty acids. Our results show how main impacts are not related to the energy involved in the two processes. In fact, the use of dedicated crops as a source of triglycerides in the biodiesel production entailed higher impacts in terms of land exploitation. On the other hand, beef tallow was assumed as a starting raw material in the production of fatty acids, and this involved some significant impacts associated with animal rearing. At the same time, however, avoiding the use of dedicated biomass ensured a lower global impact (in terms of single score). Lastly, in order to validate the model created, a sensitivity analysis using the Monte Carlo method was performed. The two routes from glycerol were also compared with the classical chemical route where acrolein is produced by propylene oxidation.
A sequential stage physico-chemical refining of crude glycerol, derived from a waste used-oil utilizing biodiesel (methyl ester) production plant, was performed by acidification, polar solvent extraction and activated carbon adsorption at a laboratory scale and ambient temperature. The effect of varying the acid type (H3PO4, H2SO4 and CH3COOH) and pH (1–6), the type of polar solvent (CH3OH, C2H5OH and C3H7OH) and their ratio to glycerol (3:1–1:3 v/v), and adsorption with activated carbon at different ratios of activated carbon to glycerol (40–200 g/l) on the purity of crude glycerol was explored. The highest glycerol purity (95.74 wt.%) was obtained with the sequential acidification to pH 2.5 with H3PO4 and phase separation, followed by extraction with C3H7OH at a solvent:crude glycerol ratio of 2:1 (v/v). Finally, adsorption with commercial activated carbon at 200 g/l also achieved a 99.7% color reduction.
Crude glycerol samples used in this study consisted of crude glycerol (CG1) produced from homogeneous catalyst (NaOH) obtained from Golden Hope biodiesel plant and crude glycerol (CG2) as a product of heterogeneous catalysed transesterification RBD palm oil using KOH/Al<SUB>2</SUB>O<SUB>3</SUB> catalyst. KOH/Al<SUB>2</SUB>O<SUB>3</SUB> catalyst was produced by wet impregnation method and characterized by using BET, XRD and SEM-EDX methods. 15% KOH/ Al<SUB>2</SUB>O<SUB>3 </SUB>has BET surface area of 26.1 m<SUP>2</SUP> g<SUP>-1</SUP> compared with 100.4 m<SUP>2</SUP> g<SUP>-1</SUP> for fresh Al<SUB>2</SUB>O<SUB>3</SUB>. The first purification stage of the crude glycerol was achieved by employing the neutralization method followed by microfiltration and ion exchange resins methods. Inorganic salts as a result of the neutralization with 85% v/v phosphoric acid were filtered using syringe filter 0.45 μm. Only glycerol peak could be detected using a Dionex C-18 column in the HPLC indicating that the neutralization step enabled the removal of excess homogeneous catalyst as well as the unreacted free fatty acids in the crude glycerol samples. The free ions from salt and catalyst were then eliminated through ion exchange process using Amberlite resins to produce higher glycerol purity. The samples were also analyzed using FTIR to check on their purity level and to detect any impurity that may still exist. The products of this 3-step purification method were deemed comparable to that of a commercial pure glycerol based on the viscosity, pH value, free fatty acid value, moisture content and density rendering them as competitive feedstock for the biolubricant production.
This work focuses on the sustainable integrated production of bioplastic, also known as Polyhydroxyalkanoate (PHA). Glycerol by-product generates from soap production and biodiesel production plant were utilized as the feedstock to overcome the current drawbacks in PHA production. Different purities of glycerol (i.e,16 wt%, 40 wt% and 60 wt%) were undergone pretreatment steps such as acidification, filtration, evaporation, hexane washing, methanol recovery and ion exchange to obtain 98 wt% of glycerol prior to PHA production. Capital of equipment purchase was estimated by using correlation and graphical method. It was found that, cost of chemical purchase for pretreatment has a high impact on the overall economy of the production. Economic feasibility of all proposed process routes was assessed by calculating the Payback period. Lastly, environmental impact of each pretreatment method was assessed by conducting an LCA by setting the annual target of 750,000 kg as the functional unit. Global warming potential, acidification potential and ecotoxicity of freshwater were chosen as the impact categories in this process. It was found that route 4 with feedstock purity of 60 wt% CG and pretreatment steps of methanol recovery, neutralization, centrifugation, water evaporation and distillation was found to be the most economically and environmentally sustainable among the assessed process routes.
The increasing effort of the global community to reduce dependency on fossil fuels led to an increase in the production of biodiesel and therefore the oversupply of crude glycerol. Different steps are necessary to ensure this oversupply of highly impure, waste-based crude glycerol (approximately 680,000 tonnes by 2024) can be made suitable for applications. This review paper aims to give an overview of the recent developments of the global glycerol market and discusses advanced crude glycerol purification technologies (as compared to physio-chemical treatments). The market overview involves information on the relevance of the global glycerol market and the different grades of glycerol which are produced. Additionally, different application areas for glycerol are detailed; including current industrial solutions, challenges, and outlooks. The second part reports newly proposed crude glycerol purification technologies from industry and recent research since 2014, their advantages and disadvantages, and feasibility in terms of industrial implementation at scale. The results of this review suggest that pressure-, thermally- and electrochemically-driven membrane-based separation technologies could solve the issue of expensive large scale vacuum distillation columns lowering capital and operating expenditures reaching > 99 % of glycerol purity. However, the increase of lower quality glycerol generated resulting from 2nd generation bio-diesel plants presents challenges due to the increasing ash and matter organic non-glycerol (MONG) impurities (due to the use of waste-based feedstocks in biodiesel production). As result, hybrid solutions may be needed since advanced purification technologies cannot be used as stand-alone solutions but need to be accompanied by a proper pre-treatment.
The dilemma of fossil fuel use, political versatility, and global climate change have driven motivation that has led to growing interest in developing and implementing renewable energy and green chemical technologies. Glycerol, a by-product of biodiesel production, has become a focus of interest among both industry and academic communities due to its low cost and potential as a renewable green chemical building block. This substance has various applications in industries such as cosmetics, food, and pharmaceuticals, and even as a fuel additive. The renewable nature of glycerol and its wide range of potential applications make it an attractive alternative to traditional petrochemical-based products. In this work, a conceptual design of integrated glycerol hydrogenolysis with on-site hydrogen produced from glycerol reforming was proposed. The primary objective was to evaluate the economic potential and possible environmental footprint of the production of high-value chemicals derived from the glycerol produced via the hydrogenolysis route. The Industrial Park at Victoria was identified and selected as the desired plant location to produce high-value chemicals (i.e., acetol, ethylene glycol, and propanediol) based on a framework structured by the triple bottom line. Overall, under the conversion of 10 tonnes of glycerol per day to 1,2-propanediol, the plant managed to yield a good return on investment (ROI) and a payback period of 16.01% and 8.72 years, respectively (base case). Moreover, environmental analysis shows that the global warming potential (in terms of CO2 emission) of the current work was two-fold lower than that of the conventional business-as-usual pathway (fossil-fuel route using propylene oxide as feedstock), suggesting that the conceptual design of an integrated glycerol hydrogenolysis process with on-site hydrogen produced from glycerol reforming is favorable in both economic and environmental aspects.
Water scarcity and the consequent increase of freshwater prices are a cause for concern in regions where shale gas is being extracted via hydraulic fracturing. Wastewater treatment methods aimed at reuse/recycle of fracking wastewater can help reduce water stress of the fracking process. Accordingly, this study assessed the catalytic performance and life cycle environmental impacts of cerium-based mixed oxide catalysts for catalytic wet oxidation (CWO) of organic contaminants, in order to investigate their potential as catalysts for fracking wastewater treatment. For these purposes, MnCeOx and CuCeOx were tested for phenol removal in the presence of concentrated NaCl (200 g L⁻¹), which represented a synthetic fracking wastewater. Removal of phenol in pure (“phenolic”) water without NaCl was also considered for comparison. Complete (100 %) phenol and a 94 % total organic carbon (TOC) removal were achieved in both the phenolic and fracking wastewaters by utilising MnCeOx (5 g L⁻¹) and insignificant metal leaching was observed. However, a much lower activity was observed when the same amount of CuCeOx was utilised: 23.3 % and 20.5 % for phenol and TOC removals, respectively, in the phenolic, and 69.1 % and 63 % in the fracking wastewater. Furthermore, severe copper leaching from CuCeOx was observed during stability tests conducted in the fracking wastewater. A life cycle assessment (LCA) study carried out as part of this work showed that the production of MnCeOx had 12–98 % lower impacts than CuCeOx due to the higher impacts of copper than manganese precursors. Furthermore, the environmental impacts of CWO were found to be 94–99 % lower than those of ozonation due to lower energy and material requirements. Overall, the results of this study suggest that the adoption of catalytic treatment would improve both the efficiency and the environmental sustainability of both the fracking wastewater treatment and the fracking process as a whole.
Rigid polyurethane foams (PUFs) traditionally rely on crude oil (fossil feedstock). Yet, the increasing concerns over environmental issues have been promoting the use of renewable/recycled feedstocks, such as crude glycerol (CG) derived from bio-based feedstocks, like soybean, rapeseed, palm and waste cooking oil (WCO). In turn, from the perspective of a circular economy, recycling PUF waste to recover its polyol or CG content and use it as a partial substituent of virgin polyol or CG in the production of new rigid PUFs (close-loop recovery), rather than disposing it in landfill, is generally seen as a suitable option. To evaluate that perception, this study compares the environmental impacts of rigid PUF produced using polyol derived from crude oil and unrefined CG derived from bio-based feedstocks, based on life cycle assessment following a cradle-to-grave approach. Three optimised formulations of PUF derived from polyol/CG were considered. Furthermore, recycling of rigid PUF wastes, to recover its polyol/CG, was compared with its disposal in landfill. The results obtained revealed that the different formulations used in this study had distinct impacts depending on the scenarios considered. Moreover, these results have also clearly demonstrated that, overall, the environmental superiority of bio-based feedstocks compared to their fossil feedstock counterpart to produce rigid PUFs cannot always be claimed. Regardless of the scenario considered, the methylene diphenyldiisocyanate (MDI) is the main hotspot for all impact categories other than marine eutrophication (ME), ranging from 50 to 98% of the total impacts. As regards the scenarios involving polyol/CG recovery, the environmental impacts from the polyol/CG recovery process exceeded the environmental benefits from the PUF waste recycling and the inherent partial replacement of virgin polyol/CG. Indeed, the polyol/CG recovery resulted in a slight increase of the total impacts compared to those without polyol/CG recovery. These results highlight the need to carry out further studies to improve the environmental performance related with polyol/CG recovery considering different chemical processes.
Glycerol is one of the industrially important chemicals having a wide range of applications in many fields. One of the important processes to obtain glycerol is during the biodiesel production, where it is formed as a by-product. However, it is crude and needs to be purified. Interestingly, the purification process of glycerol can be versatile, where it is possible to purify the crude glycerol and synthesize value-added chemical simultaneously. In this context, herein, we have developed an acidification-based process and demonstrated the concurrent purification of biodiesel-derived glycerol and the synthesis of sodium sulphate (Na2SO4) and potassium sulphate (K2SO4) as value-added chemicals. . The obtained results reveal that the established process is promising and yields commercial-grade glycerol (with ∼95% purity) along with the value-added chemicals Na2SO4 and K2SO4 with a purity of ∼95 and 98%, respectively. In addition, these synthesized powders have also been utilized as catalyst in biodiesel production with a yield of 96.1 and 94.8%, respectively with 3.5 wt% catalyst concentration. From the kinetic study, which is the pseudo-first order reaction, the activation-energy and frequency-factor for Na2SO4 and K2SO4 are estimated to be 38.27 kJ/mol and 2.2 × 10⁴ min⁻¹ and 44.69 kJ/mol and 2.4 × 10⁵ min⁻¹, respectively. The thermodynamic parameters of enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG) of Na2SO4 and K2SO4 catalysed process suggested the endothermic, endergonic, and non-spontaneous nature of the reaction. Further, the recovered Na2SO4 and K2SO4 were reused for four times in biodiesel production, which showed a consistent yield of biodiesel in all the four cycles.
The rapid industrial and economic development runs on fossil fuel and other energy sources. Limited oil reserves, environmental issues, and high transportation costs lead towards carbon unbiased renewable and sustainable fuel. Compared to other
carbon-based fuels, biodiesel is attracted worldwide as a biofuel for the reduction of global dependence on fossil fuels and the
greenhouse efect. During biodiesel production, approximately 10% of glycerol is formed in the transesterifcation process
in a biodiesel plant. The ditching of crude glycerol is important as it contains salt, free fatty acids, and methanol that cause
contamination of soil and creates environmental challenges for researchers. However, the excessive cost of crude glycerol
refning and market capacity encourage the biodiesel industries for developing a new idea for utilising and produced extra
sources of income and treat biodiesel waste. This review focuses on the signifcance of crude glycerol in the value-added
utilisation and conversion to bioethanol by a fermentation process and describes the opportunities of glycerol in various
applications.
Removal of glycerol to obtain cleaner biodiesel is a matter of concern for many industries as glycerol in biodiesel can be a fatal source of engine failure. Looking at the efficacy of ceramic membranes in separation processes, fly ash based tubular membranes are being used for this purpose. Use of fly ash in membrane fabrication itself is a step towards converting hazardous waste into valuable resource, which ultimately helps in achieving a healthy and cleaner environment. As in the production of ceramic membranes, binders play a crucial role, membranes were fabricated using different concentrations (2–3.5 wt%) of sodium salt of carboxymethyl cellulose (Na-CMC) binder in order to get the optimized membrane properties. The fabricated membranes portrayed a wide range of properties (mechanical strength 12.60–20.28 MPa, average pore diameter 0.133–0.190 μm, porosity 40.17–41.65%) and hence, an optimized binder concentration was chosen for further application. The membranes synthesized with 2 wt% Na-CMC solution (membrane M2) showed outstanding mechanical (20.28 ± 2.09 MPa) and chemical stability (6.56 ± 1.67% weight loss in acid; 2.77 ± 0.67% weight loss in base) along with a mean pore size of 0.133 μm. Membrane M2 was further taken for separation of glycerol from biodiesel emulsion. It was found that the membrane successfully removed glycerol from a synthetic solution of biodiesel and the final permeate was found to satisfy ASTM D6751 and EN14214 regulations regarding the free glycerol content in biodiesel.
The implications of climate change on a global scale have resulted in the shift towards resource circular platforms which encourages waste valorization and lowers environmental impact. Within the transport sector, biofuels-namely biodiesel, has emerged as a successful candidate promoting greater sustainable development. However , due to its growth and popularity, crude glycerol-a by-product of the biodiesel process, has remained as an underrated waste stream which threatens the inherent sustainability of the biodiesel process. Here, we showcase multiple decision criteria facilitated by techno-economic and environmental assessments, to support a resource circular biodiesel process through glycerol upcycling-utilizing anaerobic digestion (AD) for energy integration and glycerol reforming for circular methanol production. Our findings illustrate increased energy efficiency through AD, with reductions in electricity and fuel consumption across the biodiesel process promoting reduced annualized costs compared to capital-intensive circular methanol production. Insights into life cycle assessments and the use of planetary boundaries, reveal circular methanol production as the desired pathway for reduced GHG emissions associated with carbon capture and utilization. However, the subsequent increase in energy consumption necessary for thermochemical conversion inadvertently causes burden-shifting to other impact categories-consolidating higher environmental impacts specifically for human health and resource depletion; increasing penalties associated with environmental quality. Thus, in considering current and future operating costs coupled with monetisation, AD outperforms all other platforms as the most competitive resource circular initiative; providing greater sustainable operations within the biodiesel process.
Increasing biodiesel production has been favored in the last decades due to strict requirements on reduction in GHG emissions in the transportation sector, especially related to diesel fuel. Meanwhile, crude glycerol by-product in the transesterification process has been increased, becoming a bio-based alternative of common glycerin, derived from oil, mainly used in pharmaceutic and cosmetic sectors. However, the current market does not absorb bio-glycerol supply because it should be treated, with noticeable additional costs. Recent researches have tested an innovative use of bio-glycerol as a fuel (Beatrice et al in Appl Energy 102:63–71, Beatrice et al. 2013; Bohon et al in Proc Combust Inst 33:2717–2724, 2011; Quispe et al in Renew Sustain Energy Rev 27:475–493, 2013). This chapter presents the carbon footprint of co-pyrolysis process of crude glycerol in a combined heat and power (CHP) plant following life cycle assessment method and the CF value was compared with the CFs of other common CHP plant. In order to evaluate the influence of the applied allocation procedure, three allocation approaches were followed: substitution method, energy allocation, and exergy allocation. The carbon footprint of the plant varies from 0.14 kg of CO2-eq/kWh, according to the substitution method, to 0.39 kg of CO2-eq/kWh, according to the exergy allocation. In each case, the impact is lower than the other common examined technologies. The use stage is the most impactful with respect to the other life cycle stages. However, recovered heat allows to avoid about 0.34 kg of CO2-eq per kWh of electricity produced. The study aims to evidence the sustainability of energy valorization of crude glycerol.
In the present work, crude glycerol was purified by a combined strategy of physicochemical treatment and semi-continuous membrane filtration using a 5 kDa ultrafiltration tubular membrane. Three parameters – temperature, pressure, and flow rate were studied to see the effect of membrane filtration on glycerol purity. A maximum glycerol purity of 93.7% was obtained from crude glycerol of 40% purity after the physicochemical treatment and membrane filtration at the temperature, pressure, and flow rate of 50 °C, 700 kPa, and 50 mL/min, respectively. Most of the purification occurred during physicochemical treatment. Techno-economic analysis based on a scenario where all the purified glycerol is converted to value added chemicals – solketal and glycerol carbonate - showed that the glycerol purification process is economically feasible. In this scenario (scenario 3), the required capital investment was 6 million (with 10% discounting rate) or 50.85/kg and $80.36/kg, respectively, making it a promising undertaking. The results of the present work can also be useful for the purification or recovery of other valuable biodiesel by-products such as free fatty acids, soaps, and solvents.
Recent governmental policies that promote a bio-based economy have led to an increasing production of biodiesel, resulting in large amounts of waste glycerol being generated as low-cost and readily available feedstock. Here, the production of high-value bio-based propylene glycol as an alternative chemical route to valorize biodiesel glycerol was studied and assessed considering economic and life cycle environmental criteria. To this end, the conventional industrial process for propylene glycol production, which uses petroleum-based propylene oxide as feedstock, was compared against three different hydrogenolysis routes based on biodiesel glycerol using process modeling and optimization tools. The environmental impact of each alternative was evaluated following Life Cycle Assessment principles, while the main uncertainties were explicitly accounted for via stochastic modelling. Comparison among the various cases reveals that there are process alternatives based on biodiesel glycerol that outperform the current propylene glycol production scheme simultaneously in profit and environmental impact (i.e. 90 % increment in profit and 74 % reduction in environmental impact under optimum process conditions). Overall, this work demonstrates the viability to develop sustainable biorefinery schemes that convert waste glycerol into high-value commodity chemicals, like propylene glycol, thereby promoting holistic bioeconomy frameworks.
A rapid growth in biodiesel production has naturally led to a surplus of crude glycerol generated. Due to the impurities present in the crude glycerol, expensive refining processes are often necessary in order for the crude glycerol to be used in the same applications as pure glycerol. As a result, the demand for crude glycerol is quite low, and biodiesel producers must find ways to dispose it. Disposal can be costly, detrimental to the environment, and wasteful. Exploration of crude glycerol utilization is of significance for not only reducing the negative impact on the environment but also for increasing the economic benefits of biodiesel production. This paper reviewed a number of valuable and practical applications of crude glycerol in the sector of renewable energy generation through processes such as fermentation, digestion, gasification, pyrolysis, liquefaction, combustion, and steam reforming. Studies indicated that an integration of crude glycerol to other systems for energy production is a promising option despite the impurities in crude glycerol, and some processes even benefit from their presence.
Life cycle assessments (LCA) of an early research state reaction process only have laboratory experiments data available. While this is helpful in understanding the laboratory process from an environmental perspective, it gives only limited indication on the possible environmental impact of that same material or process at industrial production. Therefore, a comparative LCA study with materials that are already produced at industrial scales is not very meaningful. The scale-up of chemical processes is not such a trivial process and requires a certain understanding of the involved steps. In this paper, we elaborated a framework that helps to scale up chemical production processes for LCA studies when only data from laboratory experiments are available. Focusing on heated liquid phase batch reactions, we identified and simplified the most important calculations for the reaction step's energy use as well as for certain purification and isolation steps. For other LCA in- and output values, we provide estimations and important qualitative considerations to be able to perform such a scale-up study. Being an engineering-based approach mainly, it does not include systematically collected empirical data which would give a better picture about the uncertainty. However, it is a first approach to predict the environmental impact for certain chemical processes at an industrial production already during early laboratory research stage. It is designed to be used by LCA practitioners with limited knowledge in the field of chemistry or chemical engineering and help to perform such a scale-up based on a logical and systematic procedure.
Abstract This paper aims at highlighting considerations on the sludge status and subsequent Life Cycle Assessment modelling if a paradigm shift arose by moving from “waste” sludge to “product” sludge. Forty-four peer-reviewed papers of Life Cycle Assessment in the field of wastewater treatment have been critically reviewed to highlight the consequences of this paradigm shift on the Life Cycle Assessment method and to identify the impacts on the goal and scope step of Life Cycle Assessment questioned by the sludge status (“waste”, “waste-to-product” or “product” sludge). Results show that sludge is mainly considered as “waste-to-product” sludge. The “zero burden assumption” is always applied and sludge is never charged with an environmental burden associated with its production. This is not questionable when sewage sludge is considered as “waste” or “waste-to-product” sludge with energy recovery. However, this is becoming more debatable when sludge is considered as “product” sludge or as “waste-to-product” sludge with nutrient or material recovery. In such cases, the “zero burden assumption” is a no longer valid hypothesis as the sludge life-cycle needs to be fully considered. This can only be done if the sludge carries an upstream environmental burden. Allocating an environmental burden to the sludge appears as a challenging question requesting allocation factors between the sludge production and the water treatment for each step that generates sewage sludge.
The environmental performance of hydrogen and electricity production by supercritical water reforming
(SCWR) of glycerol was evaluated following a Life Cycle Assessment (LCA) approach. The heat-integrated
process was designed to be energy self-sufficient. Mass and energy balances needed for the study were
performed using Aspen Plus 8.4, and the environmental assessment was carried out through SimaPro
8.0. CML 2000 was selected as the life cycle impact assessment method, considering as impact categories
the global warming, ozone layer depletion, abiotic depletion, photochemical oxidant formation, eutrophication,
acidification, and cumulative energy demand. A distinction between biogenic and fossil CO2 emissions
was done to quantify a more realistic GHG inventory of 3.77 kg CO2-eq per kg H2 produced.
Additionally, the environmental profile of SCWR process was compared to other H2 production technologies
such as steam methane reforming, carbon gasification, water electrolysis and dark fermentation
among others. This way, it is shown that SCWR of glycerol allows reducing greenhouse gas emissions
and obtaining a favorable positive life cycle energy balance, achieving a good environmental performance
of H2 and power production by SCWR of glycerol.
Environmental analyses of energy systems usually lack a comprehensive perspective that takes into account their life cycle and a set of relevant impact categories. The present study tries to fulfil this need in the field of biofuel production from free fatty acid-rich wastes, therefore providing a life cycle assessment of four biodiesel production systems including esterification–transesterification of waste vegetable oils (used cooking oil) and animal fats (beef tallow, poultry fat), and in situ transesterification of sewage sludges. Reference inventory data for these systems were gathered from a literature review. Thereafter, environmental characterization values were computed for a selection of impact categories: global warming, acidification, eutrophication, ozone layer depletion, photochemical oxidant formation, and cumulative non-renewable energy demand. A comparison among the environmental profiles of these second generation biodiesel alternatives and those of first generation rapeseed and soybean biodiesel fuels and conventional low-sulphur diesel was also performed through a well-to-wheels analysis. Thus, biodiesel from waste vegetable oils potentially entailed the most favourable environmental performance. Nevertheless, actions aimed at minimizing thermal and electric energy demands are encouraged as they would lead to relevant environmental improvements.
International standards (e.g., ASTM D6751 and EN14214) limit the presence of free glycerol in biodiesel. The traditional water wash method for removing glycerol from crude fatty acid methyl esters (FAME) obtained in the production of biodiesel results in waste waters that cannot be readily discharged. To circumvent the water wash purification method, a membrane separation system using ceramic membranes was designed, constructed and tested for the removal of glycerol from crude FAME from a biodiesel production process. Ceramic membranes in the ultrafiltration (0.05μm) and microfiltration (0.2μm) ranges were tested at three different operating temperatures: 0, 5 and 25°C. All runs separated glycerol from the crude FAME. International standards for glycerol content in biodiesel were met after 3h when utilizing the ultrafiltration membrane setup at 25°C with a concentration factor greater than 1.6.
Purification of glycerol by ion exclusion has been evaluated on a laboratory scale. Many advantages can be gained using this newer method of solute separation for removing ionic impurities from crude glycerol solutions. By a method of recycle, it is possible to obtain a glycerol product of near feed concentration while reducing the ionic content to a low value. It was found that separations were improved by the use of elevated temperatures and that the optimum feed volume for this method of operation was 30-35% of the bulk resin bed volume. For maximum product concentration the feed should contain 30-35% glycerol. The salt concentration does not greatly affect the separating capacity of the resin, although higher salt concentrations will tend to improve the product concentration. For best results, the copolymer matrix should contain 4 to 12% cross-linking agent. Under these conditions it is possible to obtain a separating capacity greater than 4# of glycerol/ft.3 of resin/hour, with a product concentration of 20% or more. The application of ion exclusion to large scale purification of non-ionic materials is becoming more attractive because of the inherent low cost, simplicity of operation, and ease of unit scale-up.
Membrane technology is being increasingly used in the treatment of waters and wastewaters. The two main costs associated with the adoption of membrane filtration are the membrane module cost and the energy cost. Tradeoffs between selection of membrane capital cost and energy cost are usually identified for process optimisation; however, environmental tradeoffs associated with different operating conditions have received less attention. In order to ensure the sustainable use of membrane filtration, environmental considerations should also influence the choice of operating conditions. Here, we report on application of the method of life cycle assessment (LCA) to assess the environmental performance of different operating conditions of a microfiltration membrane (MF) process. Different membrane chemical cleaning options are compared in the sensitivity analysis component of the study. The results show that operating the MF process at a low flux with a high maximum transmembrane pressure (TMPmax) offers the most environmentally favourable outcome. The sensitivity analysis results show that in the low flux range, the choice of chemical cleaning frequency can affect the overall environmental performance of the process.
Goal, Scope, Background
To improve the environmental performance of chemical products or services, especially via comparisons of chemical products, LCA is a suitable evaluation method. However, no procedure to obtain comprehensive LCI-data on the production of fine and speciality chemicals is available to date, and information on such production processes is scarce. Thus, a procedure was developed for the estimation of LCIs of chemical production process-steps, which relies on only a small amount of input data.
Methods
A generic input-output scheme of chemical production process-steps was set up, and equations to calculate inputs and outputs were established. For most parameters in the resulting estimation procedure, default values were derived from on-site data on chemical production processes and from heuristics. Uncertainties in the estimated default values were reflected as best-case and worst-case scenarios. The procedure was applied to a case study comparing the production of two active ingredients used for crop protection. Verification and a sensitivity analysis were carried out.
Results and Discussion
It was found that the impacts from the mass and energy flows estimated by the procedure represent a significant share of the impacts assessed in the case study. In a verification, LCI-data from existing processes yielded results within the range of the estimated best-case and worst-case scenarios. Note that verification data could not be obtained for all process steps. From the verification results, it was inferred that mass and energy flows of existing processes for the production of fine and speciality chemicals correspond more frequently to the estimated best-case than to the worst-case scenario. In the sensitivity analysis, solvent demand was found to be the most crucial parameter in the environmental performance of the chemical production processes assessed.
Conclusion
Mass and energy flows in LCIs of production processes for fine and speciality chemicals should not be neglected, even if only little information on a process is available. The estimation procedure described here helps to overcome lacking information in a transparent, consistent way.
Recommendations and Outlook
Additional verifications and a more detailed estimation of the default parameters are desirable to learn more about the accuracy of the estimation procedure. The procedure should also be applied to case studies to gain insight into the usefulness of the estimation results in different decision-making contexts.
Calorific values (higher heating values, HHV) of 16 biomass samples obtained from different Turkish sources were determined experimentally and calculated from both ultimate and proximate analyses. The HHV (MJ kg(-1)) of the biomass samples as a function of fixed carbon (FC, wt%) was calculated from the following equation: HHV = 0.196(FC)+ 14.119 for which the correlation coefficient was 0.9997. The calorific values calculated from this equation showed a mean difference of 2.2%. (C) 1997 Elsevier Science Ltd.
In assessments of the environmental impacts of waste management, life-cycle assessment (LCA) helps expanding the perspective beyond the waste management system. This is important, since the indirect environmental impacts caused by surrounding systems, such as energy and material production, often override the direct impacts of the waste management system itself. However, the applicability of LCA for waste management planning and policy-making is restricted by certain limitations, some of which are characteristics inherent to LCA methodology as such, and some of which are relevant specifically in the context of waste management. Several of them are relevant also for other types of systems analysis. We have identified and discussed such characteristics with regard to how they may restrict the applicability of LCA in the context of waste management. Efforts to improve LCA with regard to these aspects are also described. We also identify what other tools are available for investigating issues that cannot be adequately dealt with by traditional LCA models, and discuss whether LCA methodology should be expanded rather than complemented by other tools to increase its scope and applicability.
Glycerine Price Trend and Forecast
- Chemanalyst
Purification of glycerine. US patent application US11/387
- J E Aiken