Article

Integrated biological treatment of fowl manure for nitrogen recovery and reuse

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  • Agricultural Research Organization (ARO), Neve Yaar, Israel
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... compost, peat, sludge, woodchips, gravel, sand, etc.) has been reported to efficiently remove NH 3 by adsorption and nitrification, even at was demonstrated by Chen et al. (2005). Recently, a scheme that includes a compost biofilter for the capture of NH 3 emitted during manure digestion and its conversion to nitrate (NO 3 − ) has been suggested (Gross et al., 2012; Posmanik et al., 2013). The manure is added in batches, and the produced NO 3 − is washed away after each cycle, thus regenerating the filter bed and improving its NH 3 removal efficiency. ...
... The produced NO 3 − -rich effluent can be applied as a liquid fertilizer in agricultural applications. Additional outputs of the suggested biofilter are effluent gases that have been characterized to be free of NH 3 and other hazardous gases such as hydrogen sulfide (H 2 S), methane (CH 4 ) and nitrous oxide (N 2 O) (Posmanik et al., 2013). This system exhibited high nitrification activity under very high NH 3 concentrations (>1700 mg m −3 ) emitted from digested manure. ...
... A pilot-scale anaerobic manure digester (as a source of NH 3 ) attached to a nitrifying compost biofilter was used as detailed by Posmanik et al. (2013) and illustrated inFig. 1. ...
Article
Ammonia emissions from poultry-manure disposal and agricultural applications pose a global environ-mental challenge that requires the development of proper management practices. Recently, a schemecomprised of a compost-based biofilter for the treatment of high loads of ammonia emitted from poultry-manure digestion (up to 500 g NH3m−3biofilter day−1) was suggested. In this study, we hypothesizedthat the high ammonia-adsorption capacity of the compost matrix creates an ammonia gradient alongthe biofilter that is occupied by adapted nitrifying communities, thus allowing high nitrification ratesand ammonia removal. Accordingly, pilot-scale compost biofilters were constructed and batch-fed withammonia emitted from digested poultry manure for over a year. The operation cycle included a nitratewashing step from the biofilter. Compost samples withdrawn at 20, 40 and 60 cm distance from thegas inlet were chemically characterized and analyzed for nitrification activity and nitrifier abundanceand diversity. The number of ammonia-oxidizing bacteria (AOB) was 0.5–1 order of magnitude lowerin the bottom section (0–20 cm), which was dominated by Nitrosomonas species, compared to the toplayers which were occupied by a mixed Nitrosomonas and Nitrosospira population. In addition, ammonia-oxidizing archaea (AOA) were homogeneously distributed along the biofilter profile and their numberswere at least one order of magnitude higher than those of the AOB. Significantly lower potential nitrifica-tion activity was detected in the bottom layer, and correlated with AOB abundance. Together, the resultsindicate that with proper operation of compost biofilters, suitable communities of nitrifying microorgan-isms that are able to cope with a wide range of ammonia concentrations, sourced from manure digestion,will develop.
... biogas potential, waste residue to return to the field, the manufacture of renewable feed and organic fertilizer etc., will be important to improve the environment in the WRB. Composting technology could be easily implemented to help manage animal manure, with composted manure then used as soil amendment and fertilizer (Dróżdż et al., 2020;Posmanik et al., 2013). Unbalanced nutrient proportions in compound fertilizers can lead to soil acidification, secondary salinization and reduced microbial activity, which reduces yields and may lead farmers to apply more fertilizers to try to compensate for the loss of soil productivity. ...
Article
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Excessive nitrogen and phosphorus inputs to land and subsequent export to water via runoff leads to aquatic ecosystem deterioration. The WRB is the world’s largest karst basin which is characterized by a fragile ecosystem coupling with high population pressure, and the transformation of intensive agriculture. Quantifying different sources of pollution in karst regions is challenging due to the complexity of landscape topography and geology coupled with high transmissivity and connectivity of subsurface hydrological systems. This results in large uncertainty associated with nitrogen (N) and phosphorus (P) flow pathways. This combination of factors contributes to the WRB being a high priority for quantitatively understanding the contribution of regional nutrient inputs and those of other major water quality determinants. Here we applied the latest statistical data (2000–2018) and simple quasi-mass-balance methods of net anthropogenic nitrogen and phosphorus inputs (NANI and NAPI) to estimate spatio-temporal heterogeneity of N and P inputs. The results show that while NANI and NAPI are first decreasing, this is followed by an increasing trend during 2000–2018, with average values of 11262.06 ± 2732 kg N km− 2 yr⁻¹ and 2653.91 ± 863 kg P km⁻² yr⁻¹ respectively. High N and P concentrations in the river drainage network are related to the spatial distribution of excessive inputs of N and P. Rapid urbanization, livestock farming and the conflicts between economic development and lagged-environmental management are the main reasons for the incremental regional N and P inputs. Management decisions on nutrient pollution in karst regions need careful consideration to reduce ecological impacts and contamination of karst aquifers. This study provides new insight for policy and decision making in the WRB, highlighting policy options for managing nutrient inputs and providing recommendations for closing the science-policy divide.
... Therefore, the PRD still had great potential in the recycling of excreta from animal husbandry by the following methods:1) Composting technology should be the most common practice for managing animal manure. Animal manure could be used as soil amendment and fertilizer as high content of N and P could improve soil physical and biological fertility (Posmanik et al., 2013;Drozdz et al., 2020). 2) Implementation of fecal energy reuse technology. ...
Article
Excess inputs of nitrogen (N) and phosphorus (P) are the main contributors of aquatic environmental deterioration. Due to the agricultural and industrial activities in the rapidly urbanized basin, the anthropogenic N and P cycle are significantly different from other regions. In this study, we took the Pearl River Delta as an example and introduced the budget list of N and P in the five survey years, including the net anthropogenic N inputs (NANI) and net anthropogenic P inputs (NAPI). The results revealed that the intensities of NANI and NAPI in this area increased from 2008 to 2010 and then decreased after 2010. The peak values were 21001 kg N km⁻²yr⁻¹ and 4515 kg P km⁻²yr⁻¹ for the intensities of NNAI and NAPI, respectively, while the lowest values decreased to 19186 kg N km⁻²yr⁻¹ and 4103 kg P km⁻²yr⁻¹ in 2016. The most important contribution of NANI and NAPI sources in this area were net N and P inputs for human food and animal feed with an average contribution of 61.41% and 76.83%, which indicated that large amounts of N and P were introduced into the environment through the food system. This study expanded the knowledge on regional environmental management from human dietary consumption, human life consumption, animal consumption and fertilizer consumption. Its reuse will be put into practice by understanding the driving factors of N and P inputs in each region of the basin, combining the urbanization characteristics.
... Treatment A had the highest aeration rate; therefore, the loss of NH + 4 -N in the form of NH 3 was greatest under these conditions. Recently, a design has been suggested that includes a compost bio-filter for the capture of NH 3 emissions and their conversion to NO − 3 during manure digestion (Posmanik et al., 2013). When Michel Jr and Reddy (1998) researched the impact of different O 2 replenishment amounts on compost, they found that NH 3 emissions increased when the O 2 replenishment amount increased. ...
... During the 71 days of the stable operation, the effluent TDN concentration averaged 305 mg/L of which TAN accounted for 83%, with negligible or undetectable concentrations of NO 2 -N and NO 3 -N (Fig. 5). Increasing aqueous N and P concentrations during anaerobic digestion has been found in many studies (Koyama et al. 2018;Yenigün and Demirel 2013) and is related to ammonification and mineralization of the organic matter (Posmanik et al. 2013). Interestingly, differential mobilization was observed as reflected by the differences between mineralization ratio of N and P. For example, TAN/TDN and SRP/TP ratios were 0.7 and 0.9, respectively. ...
Article
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Aquaponics plant waste, such as the non-edible parts of many vegetable crops, can be a source of environmental pollution, while its treatment might cause an economic burden. Therefore, efficient use of this waste would be advantageous.This study aimed at investigating anaerobic digestion of aquqponic lettuce waste to recover nutrients and energy through biogas production. A 700 L commercial anaerobic system was used to treat lettuce wastes from an aquaponic farming system that operated under desert climate and steady-state conditions. Digestion efficiency of the lettuce waste was 90.1% by weight, producing a maximum biogas volume of 0.65 m3/kg dry weight per day. Biogas composition contained on average 59.2% methane and 38.9% CO2 with only negligible hydrogen sulfide content. Moreover, the supernatant from the anaerobic digester contained elevated nutrient concentrations (N, P, K, Ca, and Fe), which can potentially be used onsite as a fertilizer. Onsite anaerobic digestion of lettuce plant waste from the aquaponic system under summer desert conditions is demonstrated for the first time to efficiently reduce pollution burden, produce high-quality biogas, and recover nutrients.
... 64 Such systems have been shown to be capable of converting high NH 4 + concentrations to NO 3 −65 while potentially reducing total N 2 O emissions. 66 Our estimations of the GWI reduction do not include the CO 2 e emissions avoided by using the RAS effluent, which would otherwise require treatment by a wastewater treatment plant. Such a treatment is estimated to emit between 230 and 830 g of the CO 2 e m −3 effluent. ...
Article
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The unlimited nitrogen (N) availability that has characterized crop production in the last few decades is accompanied by environmental burdens, including the greenhouse gas (GHG) emissions associated with fertilizer production, post-application nitrate (NO3–) pollution of water bodies, and emissions of reactive gaseous N forms into the atmosphere. Here, we quantified the environmental tradeoffs of replacing mineral N fertilizer with NO3– and ammonium (NH4⁺) originating from effluent water of aquaculture in a cucumber (Cucumis sativus) cultivation system. While the yield, nitrogen use efficiency (NUE), and NO3– leaching were similar between the cucumbers fertilized and irrigated (fertigated) by aquaculture effluent water containing 100 mg of NO3–-N L–1 (AN), by aquaculture effluent water supplemented with NH4⁺ (AN+), or by tap water with NO3– and NH4⁺ added (FN+), there were significant differences in the nitrous oxide (N2O) emissions between the systems. The N2O emissions peaked after each irrigation event followed by an exponential decline. The cumulative N2O emissions were between 60 and 600 g N2O-N ha–1, smaller than predicted based on a fertilizer application rate of 600 kg N ha–1 and were in the order AN+ ≫ FN+ > AN.
... A total fertigation rate of 100 mg L −1 dissolved N was chosen since it is the typical application rate for lettuce. 27,30 The fertigation treatments were prepared twice a week and stored in irrigation barrels. Samples were collected from each treatment at the time of preparation and disposal and, then, characterized. ...
Article
Hydrothermal carbonization (HTC) has received much attention in recent years as a process to convert wet organic waste into carbon-rich hydrochar. The process also generates an aqueous phase that is still largely considered a burden. The success of HTC is dependent on finding solutions for the aqueous phase. In the present study, we provide the first investigation of recirculation of the aqueous phase from HTC of poultry litter as a means to concentrate nutrients, and its subsequent application to agriculture as a fertilizer. Aqueous-phase recirculation generally resulted in an increase in nitrogen, phosphorus and potassium concentrations up to cycle 3 with maximum concentrations reaching up to 5400, 397, and 23300 mg L-1 for N, P and K, respectively. Recirculation did not adversely affect hydrochar composition or calorific value. The recirculated and non-recirculated aqueous phases were able to support lettuce growth similar to a commercial fertilizer. Results from this study indicate that the combination of aqueous-phase recirculation and use as a fertilizer can be a suitable method to reutilize the aqueous phase and recycle nutrients back into agriculture, thus increasing HTC efficiency and economic feasibility.
... Samples were injected manually using a 500-μL gas-tight syringe. Analysis followed a well-established procedure (Posmanik et al., 2013). Nitrate (NO 3 -N) and TAN in the solutions were analyzed according to standard methods (APHA, 2005). ...
Article
The development of intensive recirculating aquaculture systems (RAS) with low water exchange has accelerated in recent years as a result of environmental, economic and other concerns. In these systems, fish are commonly grown at high density, 50 to 150kg/m3, using high-protein (30%-60%) feeds. Typically, the RAS consists of a solid treatment and a nitrification unit; in more advanced RAS, there is an additional denitrification step. Nitrous oxide (N2O), a byproduct during nitrification and denitrification processes, is a potent greenhouse gas that destroys the ozone layer. The aim of this study was to measure and assess N2O emissions from a near-zero discharge land-based saline RAS. N2O flux was monitored from the RAS's fish tank, and moving-bed nitrification and activated-sludge (with intrinsic C source) denitrification reactors. N2O emission potential was also analyzed in the laboratory. N2O flux from the denitrification reactors ranged between 6.5 and 48mg/day, equivalent to 1.27±1.01% of the removed nitrate-N. Direct analysis from the fish tank and nitrification reactors could not be performed due to high aeration, which diluted the N2O concentration to below detection limits. Thus, its potential emission was estimated in the laboratory: from the fishponds, it was negligible; from the nitrification reactor, it ranged between 0.4 and 2.8% of the total ammonia-N oxidized. The potential N2O emission from the denitrification reactor was 3.72±2.75% of the reduced nitrate-N, within the range found in the direct measurement. Overall, N2O emission during N transformation in a RAS was evaluated to be 885mg/kg feed or 1.36g/kg fish production, accounting for 1.23% of total N application. Consequently, it is estimated that N2O emission from aquaculture currently accounts for 2.4% of the total agricultural N2O emission, but will decrease to 1.7% by 2030.
... Treatment A had the highest aeration rate; therefore, the loss of NH + 4 -N in the form of NH 3 was greatest under these conditions. Recently, a design has been suggested that includes a compost bio-filter for the capture of NH 3 emissions and their conversion to NO − 3 during manure digestion (Posmanik et al., 2013). When Michel Jr and Reddy (1998) researched the impact of different O 2 replenishment amounts on compost, they found that NH 3 emissions increased when the O 2 replenishment amount increased. ...
Article
Full-text available
Composting is a controlled biological process used to stabilize and transform waste into a soil treatment. Aeration rate is one factor that controls the process of composting, as it ensures the growth of adequate aerobic microbe populations. To investigate the effect of aeration rates on the physicochemical indexes of compost and the loss of nitrogen content during composting, aerobic composting processes with different aeration rates (A: 0.2 L min-1 kg-1 TS, B: 0.05 L min-1 kg-1 TS and C: 0 L min-1 kg-1 TS) were studied. Ammonium-nitrogen, nitrate nitrogen, total nitrogen and other factors in compost samples from different periods were measured. The results showed that aeration rate significantly affected O2 content under different conditions. The aeration rate also significantly affected water content, nitrate nitrogen, and nitrogen loss. NH3 emissions increased as aeration rates increased at high temperatures owing to nitrogen loss. These results showed that aeration rate had a significant effect on total nitrogen and ammonia emissions (p<0.05). Thus, optimization of the ventilation method could significantly increase seed germination rate.
... Therefore, its application has the potential for emissions of gaseous ammonia in addition to nitrous-oxide (Gross et al., 2008;Nkoa, 2013). The anaerobic digestion of poultry manure following ammonia striping (Gross et al., 2012;Posmanik et al., 2013), may form manure digestate with mostly organic N, i.e., negligible amounts of inorganic N. The fate of these constituents when applied to agricultural soil under extreme desert conditions was not studied before. Particularly, we asked whether these amendments contribute to N 2 O emissions. ...
Article
Expansion of dryland agriculture requires intensive supplement of organic fertilizers to improve the fertility of nutrient-poor desert soils. The environmental impact of organic supplements in hot desert climates is not well understood. We report on seasonal emissions of nitrous oxide (N2O) from sand and loess soils, amended with limed and non-limed anaerobic digestate of poultry manure in the Israeli Negev desert. All amended soils had substantially higher N2O emissions, particularly during winter applications, compared to unammended soils. Winter emissions from amended loess (10–175 mg N2O m−2 day−1) were markedly higher than winter emissions from amended sand (2–7 mg N2O m−2 day−1). Enumeration of marker genes for nitrification and denitrification suggested that both have contributed to N2O emissions according to prevailing environmental conditions. Lime treatment of digested manure inhibited N2O emissions regardless of season or soil type, thus reducing the environmental impact of amending desert soils with manure digestate.
... Intensive livestock production generates large amounts of manure that pose serious environmental problems, such as odor and eutrophication of freshwater. Composting is one of the best-known processes to solve these environmental problems by transforming manures into a safer and more stabilized material, which can be applied to agricultural land to recycle the valuable nutrients and improve soil physical properties Makan, 2015;Moral et al., 2009;Posmanik et al., 2013). ...
... Other biological or physico-chemical methods could be applied to recover the stripped ammonia. A nitrification bio-filter converts the stripped ammonia into nitrogenous compounds: the nitrate compounds can be collected and converted in nitrogen-rich compost (Burke, 2006;Posmanik et al., 2013). The capability to upgrade the biogas quality using the biogas produced in AD to strip ammonia out of digestate and the N-rich gas to precipitate insoluble ammonium carbonates and bicarbonates increasing the energy content of the final biogas line has also been also explored (Burke, 2010). ...
Thesis
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Anaerobic digestion of source segregated domestic food waste (SS-DFW) offers a sustainable management route for reclaiming potential energy in the form of a fuel gas, and nutrients which can be recycled back to land. However, the biochemical characteristics of SS-DFW can lead to free ammonia nitrogen (FAN) concentrations that are inhibitory to the digestion process causing unstable operation and in some cases complete process failure, particularly in thermophilic systems. With the purpose of reducing the total ammoniacal nitrogen (TAN) in the digester, side-stream and in situ biogas stripping technologies were tested. Mesophilic and thermophilic temperatures were evaluated under moderate and complete biogas mixing rates (0.4 l min-1 – 2.6 l min-1) in a batch system. Laboratory investigations showed that TAN reductions in an in situ bubbling reactor with moderate and complete gas mixing rates were non-existent at mesophilic temperatures and minimal at thermophilic temperatures. For this reason, it is unlikely that in situ biogas stripping would be adequate to prevent TAN concentrations greater than 2500 mg N l-1 in a food waste digester and thus will not mitigate ammonia inhibition in a thermophilic system. Semi-continuous trials carried out on SS-DFW in laboratory-scale digesters, fed daily at an organic loading rate (OLR) of 2 kg VS m-3 day-1 and coupled to stripping columns at low bleed rates (2 – 3.5 % digester volume per day treated in the stripping process) were effective in reducing ammonia concentrations to below thermophilic toxic levels (TAN concentration of 2500 – 3500 mg N l-1). The experiments also confirmed that removal of a proportion of the digester contents and their exposure to thermophilic conditions with pH adjustment to 10 had no adverse effects on performance in terms of biogas production (0.83 ± 0.03 l g-1 VS without stripping, 0.84 ± 0.05 l g-1 VS with stripping) or VS destruction (81.8 % without stripping, 88.5 % with stripping). The process required high pH and temperature (≥70 ⁰C) to achieve a TAN concentration below the toxic threshold for thermophilic digestion, and it is unlikely that stripping at 55 ⁰C and pH 10 would achieve the target reduction. The research showed the way forward for the application of side-stream stripping to prevent the build-up of ammonia under thermophilic conditions, if the digester is started up with a non-inhibitory FAN concentration in the inoculum.
... Further, the rapid reduction of TAN could be attributed to its volatilization into free ammonia due to aeration (Liao et al., 1995). Shifting of pH towards alkaline due to algal growth could also be a possible reason for rapid TAN removal from LSW (Posmanik et al., 2013). The final removal of TAN and sCOD at the end of the experiments (16 d) was 98 and 80%, respectively. ...
Article
In the present work four algae were tested for their biomass production potential in neat livestock wastewater. Chroococcus sp.1 was found to be the best for biomass production under controlled (2.13 g L–1) and outdoor conditions (4.44 g L–1) with > 80% of nutrients removal. The produced biomass was then digested with cattle dung as cosubstrate. Interestingly, up to 291.83 ± 3.904 mL CH4 g–1 VSfed was produced during codigestion studies (C/N ≈ 13.0/1). In contrast to this, only 202.49 ± 11.19 and 141.70 ± 2.57 mL CH4 g–1 VSfed was recorded with algae (C/N ≈ 9.26/1) and cattle dung (C/N ≈ 31.56/1) alone, respectively. The estimated renewable power generation potential of the investigated coupled process was around 333.79 to 576.57 kWh d–1 for a dairy farm with 100 adult cattle. However, further scale-up and testing is needed to make this process a reality.
Conference Paper
Commonly used management practices of manure involve anaerobic digestion followed by land application of the digested manure. Lime treatment has been suggested as a further disinfection step, to eliminate residual pathogens. Recently, we suggested a combined treatment in which ammonia (NH3) from manure digestion is diverted into a compost nitrifying biofilter, and the resulting nitrate is recovered and reused. In the current study, poultry manure was anaerobically digested with and without the addition of lime towards the end of the digestion. The exhaust gas was passed through the biofilter and the digested manure (with and without lime) was land applied onto sandy soil. Emissions of NH3 and nitrous oxide (N2O) were quantified during manure digestion, lime treatment and the biofiltration, as well as from the digested manure-applied soil. During the anaerobic digestion, emissions ranging from 14 to 190 and 0.2 to 21 mg kg-1 manure h-1 of NH3 and N2O were recorded, respectively. These emissions have been completely mitigated by the compost biofilter. High efficiency of the biofiltration process was attributed to the compost’s adsorption capacity and to the recovery of nitrate, which enhanced the system’s nitrification activity, balanced the pH and improved the capacity to capture additional NH3. Fluxes of N2O following land application of digested manure, ranged between 0.3 and 1.7 mg m-2 day-1. Interestingly, lime treatment of the digested manure before its land application reduced N2O emission.
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Animal production results in conversion of feeds into valuable products such as meat, milk, eggs, and wool as well as into unavoidable and less desirable waste products. Intensification of animal numbers and increasing urbanization has resulted in considerable attention to odorous gases produced from animal wastes. It is clear that animal manure was, and still is, a valuable resource. However, it may be a major obstacle to future development of the animal industry if its impact on the environment is not properly controlled. Poor odor prevention and control from animal wastes is related to a lack of knowledge of the fundamental nature of odor and its production by farm animals. Odor, like noise, is a nuisance or disturbance and there is no universally accepted definition of an objectionable odor. Thus, regulation and control of odors in the environment is difficult because of the technical difficulties of defining odor limits and their measurement and evaluation. A variety of direct (sensory) and indirect (analytical instruments) methods for measuring odor intensity and determination of individual or key odor components are discussed. The biological origins of the four principal classes of odor compounds, namely branched- and straight-chain VFA, ammonia and volatile amines, indoles and phenols, and the volatile sulfur-containing compounds, are reviewed. Because more than 50% of N from animals is excreted as urea, one strategy to conserve N in waste is to inhibit the urease enzyme that converts urea to ammonia. Laboratory studies to evaluate di- and triamide compounds to control urea hydrolysis in slurries of cattle and swine wastes are presented. Finally, a brief overview of various intervention strategies is provided. Multiple combinations of nutritional management, housing systems, treatment options as well as storage and disposal of animal wastes will be required to reduce environmental pollution and provide for long-term sustainable growth.
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The land disposal of waste from the poultry industry and subsequent environmental implications has stimulated interest into cleaner and more useful disposal options. The review presented here details advances in the three main alternative disposal routes for poultry litter, specifically in the last decade. Results of experimental investigations into the optimisation of composting, anaerobic digestion and direct combustion are summarised. These technologies open up increased opportunities to market the energy and nutrients in poultry litter to agricultural and non-agricultural uses. Common problems experienced by the current technologies are the existence and fate of nitrogen as ammonia, pH and temperature levels, moisture content and the economics of alternative disposal methods. Further advancement of these technologies is currently receiving increased interest, both academically and commercially. However, significant financial incentives are required to attract the agricultural industry.
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Sufficient alkalinity is essential for proper pH control. Alkalinity serves as a buffer that prevents rapid change in pH. Enzymatic activity or digester performance is influenced by pH. Acceptable enzymatic activity of acid-forming bacteria occurs above pH 5.0, but acceptable enzymatic activity of methane-forming bacteria does not occur below pH 6.2 Most anaerobic bacteria, including methane-forming bacteria, perform well within a pH range of 6.8 to 7.2.
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Nitrobacter, a ubiquitous nitrite oxidizer in natural and anthropized environments, is commonly studied as the model genus performing the second stage of nitrification. In rivers, wastewater treatment plant discharges may affect the nitrite-oxidizing activity and the responsible genera that are largely associated with sediment. We used a laboratory batch culture approach with Nitrobacter wynogradskyi ssp. agilis strain AG and Nitrobacter hamburgensis strain X14 to characterize the possible stress effect of wastewater effluent on these populations and to study the possible competition between an effluent strain (X14) and a sediment strain (AG) over a 42-day incubation time. Immunofluorescence enumerations of each strain showed that they both survived and settled in the sediment, indicating that there was no significant stress effect due to chemical changes caused by the effluent. The development of the strains' density and activity was directly correlated with the available nitrite concentration. Nevertheless, the potential specific activity was not constant along the so-called mixotrophic (non-limiting nitrite concentration) and heterotrophic (nitrite depletion) conditions. This illustrates the inducibility of the nitrite oxidoreductase and indicates the metabolic versatility of the strains. In our experimental conditions, the preferentially autotrophic AG strain appeared more competitive than the preferentially mixo- or heterotrophic X14 strain, including in heterotrophic environment. © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
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The microbial community in sludge-treated and nearby untreated soils was investigated using direct microscopic counting, plate culture, carbon substrate utilisation (Biolog™), and fatty acid methyl esters. Long-term sewage sludge applications had resulted in higher concentrations of organic carbon and had altered other factors in the soil, including the concentration of metals. Bioluminescence was inhibited in assays of the sludge-treated soil, although microbial counts were similar in all soils. A detailed analysis of carbon substrate utilisation patterns and fatty acid methyl esters showed qualitative differences in the microbial populations. This work shows that a variety of approaches are required to assess microbial communities in soil where, despite large differences in land management, the populations are similar in size and overall composition.
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Solubility of CO2 and N2O in Twelve Solvents, 18° to 36° C.-Since according to the Lewis-Langmuir theory these two gases have similar molecular structures, it is of interest to compare their solubilities in various liquids. In the method adopted, the air was thoroughly removed from the solvent by boiling and then the gas to be tested, having been carefully purified with the help of liquid air, was admitted and shaken up with the solvent until no further solution took place. Observations accurate to better than one per cent. were made for water, acetone, acetic acid, methyl alcohol, pyridine, ethyl alcohol, benzaldehyde, aniline, amyl acetate, ethylene bromide, isoamyl alcohol, and chloroform. Taken in this order, the ratio of the solubility of CO2 to that of N2O decreases regularly from 1.34 (20°) for water to 0.66 for chloroform. This range of variation is small, and moreover the ratio is nearly constant for each solvent, changing less than one per cent. for six solvents, and not more than three per cent. for the others except chloroform and acetone. Also, the temperature coefficient (dssdT) is in most cases nearly the same for the two gases. It is always negative, the solubility decreasing with increasing temperature. Discussion of Suggested Solubility Relations, for Gases in Liquids.-Raoult's law does not hold for the solubility of gases in liquids. It is also shown that there is little, if any, relation between solubility and the difference between the internal or cohesion pressures of solvent and solute. However, the ratio of the solubilities of CO2 and N2O varies regularly with the dielectric constant of the solvent, and since this constant may be taken as an index of the polarity of the solvent and since CO2 is more active chemically and therefore has stronger polarity than N2O, this result suggests that polarity may be an important factor in determining the relative solubility of gases in liquids.
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Confined animal feeding dairy operations have generated excess amounts of manure, creating a need to identify alternative uses for this plant nutrient source. The objectives in this study were to (i) study the effect of composted dairy manure on Windthorst soil (fine, mixed, active, thermic Udic Paleustalfs), (ii) evaluate two soil testing methods for measuring P when composted dairy manure is applied, and (iii) determine tall wheatgrass (Thinopyrum ponticum (Podp.) Barkworth & Dewey 'Jose') yield response to six rates of composted dairy manure and two rates of inorganic N fertilizer. A randomized complete block design experiment arranged in a split-plot with four replications was initiated in 2001. Main plots received a single application of composted dairy manure at rates of 0, 11.2, 22.4, 44.8, 89.6, and 179.2 Mg ha21, which were incorporated before planting tall wheatgrass at the rate of 17 kg ha21. Subplots received annual split applications of inorganic N at 224 or 336 kg ha21. Composted dairy manure averaged across the 2002-2003 and 2003-2004 growing seasons increased soil organic mat- ter (OM) 54%, pH 55%, infiltration rate 550%, P 480%, and K 84% in this soil. The improved soil properties increased dry matter (DM) yields each growing season (2002-2003 and 2003-2004) up to 96 and 58%, respectively. Tall wheatgrass had similar crude protein (CP) (158-231 g kg21), DM yields (3858-9536 kg ha21), P concentrations (1.4-2.8 g P kg21), and P removal rates (5.4-26.7 kg ha21) compared to other cool-season perennial grasses.
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This paper presents fundamental and theoretical aspects of biological waste gas treatment technologies as well as examples of applications to different compounds. The three most widely used technologies are described, namely biofiltration, bioscrubbing and trickling biofiltration, focusing more extensively on biofiltration which is the most studied and most extensively used process. A description of the different technologies from technological and economic points of view, including an analysis of models used in waste gas biotreatment is given. Results presented in the literature concerning the removal of aliphatic, aromatic and mixtures of contaminants are reviewed. Carrier materials, inocula selected and alternatives proposed for regulating moisture content, pH values or for controlling pressure drop are considered. New technologies and reactor design studied at laboratory-scale are mentioned. (C) 1998 SCI.
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Leachate from a municipal landfill receiving both household and industrial waste was treated in pilot scale suspended carrier biofilm reactors for removal of nitrogen and organic matter. Nitrification was studied in two parallel aerated reactors, filled to 60% (v/v) with two different models of carrier media with specific surface areas of 210 and 390m2/m3 media, respectively. Denitrification was carried out in a mechanically stirred, anoxic reactor filled to 40% with the carrier media having a surface area of 210m2/m3. Nitrified leachate from one of the aerobic reactors was fed to the anoxic reactor together with external carbon source, initially acetic acid and later methanol, to promote denitrification. The leachate temperature varied between 10 and 26°C during the study. Nitrification proceeded well in this temperature range. The highest volumetric nitrification rate, 24g N/m3 reactorh (16°C), was obtained for the media with the largest surface area. The maximum denitrification rate with methanol as carbon source was approximately 55g N/m3h. As the process had reached optimal operation, inorganic nitrogen was almost completely removed and the removal of total nitrogen was approximately 90%. The chemical oxygen demand (COD) removal was around 20% during the study.
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A novel system for organic waste stabilization and reuse, combined with production of nitrate-rich liquid fertilizer was developed by manure digestion followed by volatilization of ammonia-rich gas (originating in manure extract) and its nitrification and recovery. This approach has several advantages, including biowaste stabilization and high recovery (over 60%) of manure N mainly as nitrate which is a better N form for many plants as compared to ammonium as the sole fertilizer N. Moreover, the potential utilization of different wastes as N sources in organic horticulture is possible as well as removal of suspended particles and microorganisms (including pathogens) that might otherwise clog the irrigation system and pose health risks, respectively. In a pilot-scale study, the system yielded several hundred liters of nitrate-rich (ca. 11 g N L−1) liquid fertilizer using guano as substrate. In a fertilization experiment, lettuce fertigated with the nitrate-rich extract exhibited better growth and quality compared to the common organic practice of fertigation with guano extract. The resulting stabilized biowaste was estimated as “low-risk” according to current guidelines and may be used for liming or land application.
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Crops, as the basic source of essential substances and nutrients, do not always contain sufficient amounts of these essential nutrients to meet dietary requirements. In this review paper, we discussed the effects of fertilization and other agronomic measures on the nutritional quality of cereal, oilseed and protein crops, tuber plants and vegetables. Research indicates that application of N, P, K and S fertilizers generally increases crop yield as well as nutritional quality. For example, fertilizer increased protein concentration in cereals and pulses, oil concentration in oilseed crops, starch concentration in tubers, and concentration of essential amino acids and vitamins in vegetables. However, excessive fertilizer application, especially N fertilizer, can result in undesirable changes such as increases in nitrate, titratable acidity and acid to sugar ratio, while decreasing the concentration of vitamin C, soluble sugar, soluble solids, and Mg and Ca in some crops. Other agronomic measures, such as tillage and crop rotation, organic farming, soil moisture management, and crop breeding and genetic engineering can also have a large effect on food crop quality, though the potential benefits of these measures for improving crop quality has not been fully exploited. Research literature on this subject suggests that more information is needed in order to achieve an increase in the concentration of essential microelements, prevent accumulation of toxic levels of elements such as Cu, Mo, Zn, Ni, Se and nitrate, and other dangerous or toxic substances and elements in crops. Copyright © 2007 Society of Chemical Industry
Article
This paper presents fundamental and theoretical aspects of biological waste gas treatment technologies as well as examples of applications to different compounds. The three most widely used technologies are described, namely biofiltration, bioscrubbing and trickling biofiltration, focusing more extensively on biofiltration which is the most studied and most extensively used process. A description of the different technologies from technological and economic points of view, including an analysis of models used in waste gas biotreatment is given. Results presented in the literature concerning the removal of aliphatic, aromatic and mixtures of contaminants are reviewed. Carrier materials, inocula selected and alternatives proposed for regulating moisture content, pH values or for controlling pressure drop are considered. New technologies and reactor design studied at laboratory-scale are mentioned. © 1998 SCI
Article
Field and pot trials were established to assess potential benefits and adverse effects of amending a sandy loam soil, under grazed ryegrass-clover pasture, with compost manufactured from wastewater biosolids, wood waste and green waste. Compost was applied to the field trial site annually for 4 years and the pot trials used soil from the field trial site each year after compost application. The pot trials demonstrated that yield of silver beet (Beta vulgaris L.) increased with increasing compost application rate and that plant metal uptake was (except for Zn) unrelated or inversely related to soil metal concentrations. In samples from the field trial, soil total C, N, P and Olsen P increased markedly with increasing compost application rate. Cation exchange capacity, exchangeable cations and total-extractable and EDTA-extractable metals (Cd, Cr, Cu, Ni, Pb and Zn) were also elevated, total Cu to the limit allowable in biosolids-amended soil. Soil basal respiration, microbial biomass C and anaerobically mineralisable N were significantly increased in the amended plots. Anaerobically mineralisable N was highly correlated with respiration (r =0.98, n =24) and only weakly related to microbial biomass C, probably indicating that a high proportion of the N mineralised was from the compost organic matter. Sulphatase and phosphatase activities increased, but not significantly, and there were no measurable effects on rhizobial numbers or on sensitive microbial biosensors (Rhizotox C and lux-marked Escherichia coli). Biosolids compost application enhanced soil fertility, productivity and microbial biomass and activity, with no apparent adverse effects attributable to heavy metals.
Article
Abatement strategies for direct emissions of greenhouse gases from animal husbandry are discussed. The reduction options are divided into preventive and `end of pipe' options. Preventive measures reduce either the carbon and nitrogen input into the system of animal husbandry or their output from the system, respectively. `End of pipe' measures reduce the formation of greenhouse gases from carbon and nitrogen within the system of animal husbandry. While animals with a high productivity fed with an optimized diet seem to be the best preventive measure, anaerobic digestion of the animal's excreta may be the most efficient way to reduce greenhouse gas emissions within animal husbandry.
Article
Liquid animal manure and its management contributes to environmental problems such as, global warming, acidification, and eutrophication. To address these environmental issues and their related costs manure processing technologies were developed. The objective here was to assess the environmental consequences of a new manure processing technology that separates manure into a solid and liquid fraction and de-waters the liquid fraction by means of reverse osmosis. This results in a liquid mineral concentrate used as mineral nitrogen and potassium fertilizer and a solid fraction used for bio-energy production or as phosphorus fertilizer. Five environmental impact categories were quantified using life cycle assessment: climate change (CC), terrestrial acidification (TA), marine eutrophication (ME), particulate matter formation (PMF), and fossil fuel depletion (FFD). For pig as well as dairy cattle manure, we compared a scenario with the processing method and a scenario with additional anaerobic digestion of the solid fraction to a reference situation applying only liquid manure. Comparisons were based on a functional unit of 1 ton liquid manure. System boundaries were set from the manure storage under the animal house to the field application of all end products. Scenarios with only manure processing increased the environmental impact for most impact categories compared to the reference: ME did not change, whereas, TA and PMF increased up to 44% as a result of NH3 and NO(x) emissions from processing and storage of solid fraction. Including digestion reduced CC by 117% for pig manure and 104% for dairy cattle manure, mainly because of substituted electricity and avoided N2O emission from storage of solid fraction. FFD decreased by 59% for pig manure and increased 19% for dairy cattle manure. TA and PMF remained higher compared to the reference. Sensitivity analysis showed that CH4 emission from manure storage, NH3 emission from processing, and the replaced nitrogen fertilizer by the mineral concentrate were important parameters affecting final results. It was concluded that processing fattening pig and dairy cattle manure to produce mineral fertilizer increased overall environmental consequences in terms of CC (except for dairy cattle manure), TA, PMF, and FFD compared to current agricultural practice. Adding the production of bio-energy reduced CC and FFD. Only when NH3 emission from processing was low and bio-energy was produced, overall equal or better environmental performance was obtained for TA and PMF. It was emphasized that real time measurements should be done to enhance the environmental assessment of manure processing technologies. Results of this study present the full environmental consequences of manure processing and key parameters affecting the environmental impact of manure management. Outcomes can be used for decision making and further tackling of environmental problems related to manure management.
Article
Numerous researchers have demonstrated that the rate and extent of the degradation of municipal solid waste (MSW) can be enhanced beyond that observed in a conventional landfill by adding moisture, buffering agents and sources of microorganisms such as anaerobically digested sludge. One method of achieving the addition of these agents is by directing leachate that has trickled through a bed of anaerobically stabilised waste to beds of fresh MSW. Proper operational strategies need to be developed for successful implementation of this process on a large scale or in a landfill. Operational parameters of primary importance are the point of time at which a stabilised waste bed can be used for sequencing, the period of sequencing and the minimal amount of leachate that has to be recirculated to rapidly attain balanced microbial activity in a fresh waste bed. Assays that measure a substrate-specific methanogenic activity of an anaerobic microbial consortia have been previously developed by researchers. These assays were employed in this study to evaluate the microbial activity of the leachate for utilisation of substrates like cellulose, acetate and formate. Activity in leachate samples, taken from a batch of MSW at various times during the degradation process, was measured in terms of the amount of methane produced in 4 h after spiking the sample with one of the selected substrates. Activity resulting from the utilisation of formate and cellulose showed considerable promise as indicators for optimising operational strategies. It was observed that the formate degradation activity followed the methane production rate with both reaching a maximum at the same time and that this could be used as an indicator for determining the period of sequencing. Cellulase activity in fresh waste beds responded to flushes of mature leachate and peaked a few days after sequencing was terminated.
Article
Dairy farming is the largest agricultural source of the greenhouse gases methane (CH4) and nitrous oxide (N2O) in Europe. A whole-farm modeling approach was used to investigate promising mitigation measures. The effects of potential mitigation measures were modeled to obtain estimates of net greenhouse gas (GHG) emissions from representative dairy model farms in five European regions. The potential to reduce farm GHG emissions was calculated per kg milk to compare organic and conventional production systems and to investigate region and system specific differences. An optimized lifetime efficiency of dairy cows reduced GHG emissions by up to 13% compared to baseline model farms. The evaluation of frequent removal of manure from animal housing into outside covered storage reduced farm GHG emissions by up to 7.1%. Scraping of fouled surfaces per se was not an effective option since the reduction in GHG emissions from animal housing was more than out-weighed by increased emissions from the storage and after field application. Manure application by trail hose and injection, respectively, was found to reduce farm GHG emissions on average by 0.7 and 3.2% compared to broadcasting. The calculated model scenarios for anaerobic digestion demonstrated that biogas production could be a very efficient and cost-effective option to reduce GHG emissions. The efficiency of this mitigation measure depends on the amount and quality of organic matter used for co-digestion, and how much of the thermal energy produced is exploited. A reduction of GHG emissions by up to 96% was observed when all thermal energy produced was used to substitute fossil fuels. Potential measures and strategies were scaled up to the level of European regions to estimate their overall mitigation potential. The mitigation potential of different strategies based on a combination of measures ranged from −25 up to −105% compared to baseline model farms. A full implementation of the most effective strategy could result in a total GHG emission reduction of about 50 Mt of carbon dioxide (CO2) equivalents per year for conventional dairy farms of EU(15) comparable to the defined model farms.
Article
Nitrification rate as a function of total ammonia nitrogen (TAN) concentration, with and without the interaction of organic matter, was investigated for three types of biofilters of laboratory scale: floating bead filter, fluidized sand filter, and submerged bio-cube filter. The performance of each type of biofilter was evaluated using a 5-reactor series with synthetic solutions containing different carbon/nitrogen ratios (C/N = 0, 0.5, and 2.0). The tests were run at representative cool water aquaculture system temperatures of 15 and 20 °C. The experimental results showed, within the lower total ammonia concentration range, a first-order nitrification rate with a highly linear regression for all three types of biofilters without the interaction of organic carbon at both test temperatures. However, with the addition of organic carbon, the nitrification rate of all three types of biofilters decreased exponentially. The reduction of nitrification rates of the biofilters was about 60–70% for a substrate concentration of 10 mg TAN l−1 when the COD/N ratio increased from 0 to 3. The temperature impact on biofilter nitrification rate was not significant under the two temperatures tested. The results of this study provide useful information for nitrification biofilter design of cool and cold water applications.
Article
Intensive recirculating aquaculture systems (RAS) produce high volumes of biosolid waste. The high salinity of brackish/marine sludge limits its use in landfill sites and waste outflows and it is a source of pollution. A reduction in sludge mass would therefore minimize the potential environmental hazard and economic burden stemming from its disposal. The aims of the current study were: 1) to characterize brackish aquaculture sludge (BAS) from three RAS in order to test for potentially suitable treatments, and 2) to test the BAS's suitability for anaerobic digestion in an upflow anaerobic sludge blanket reactor (UASB). Brackish sludge from three intensive RAS was collected periodically and analyzed for a variety of physical and chemical parameters. The mean sludge electrical conductivity and pH values ranged from 4.0 to 8.6 mS cm− 1 and 7.0 to 7.7, respectively. A low sludge redox potential averaging − 80 mV and dissolved oxygen concentrations of less than 1 mg l− 1 indicated the existence of anaerobic conditions. Volatile solids comprised 56 to 76% of the dry weight and the sludge volume index ranged from 44 to 69 ml g − 1. High concentrations of total nitrogen and total carbon were also observed, resulting in a C:N ratio ranging between 8.1 and 10.3. Toxic and/or inhibitory compounds for methanogenesis such as nitrites, nitrates and sulfides were almost absent. Sludge BOD5 ranged from 10 to 30% dry weight. These data suggest that BAS may be used in anaerobic digestion and methanogenesis without pretreatment. This concept was tested by digesting aquaculture sludge in UASB reactors. Despite the high sulfate and phosphate concentrations in the BAS, these were found not to be inhibitory to methanogenesis. Up to 70% sludge-mass reduction and an average of 40% methane production were demonstrated.
Article
A UK inventory of the nitrous oxide (N2O) emissions from farmed livestock was compiled to identify areas where potential abatement practices may be effective. Where possible, emission factors based on direct experimental data gathered under UK conditions were used, but published data were used when this was not feasible, together with statistical information, which included details of numbers of animals within each category of a species, animal liveweights, number of days housed, excretal rates and volumes of manures in stores. Total N2O emissions were calculated for each component of livestock production systems, i.e. animal houses, manure stores, following application of manures to land and during grazing. Emissions were also estimated from land used for forage conservation and tillage. Total annual N2O emissions from UK farmed livestock, based mainly on 1996 animal census data, were estimated to be 38.27 kt. The two main terms were 22.66 kt N2O from mineral fertilisers after application to soils and 5.61 kt N2O from stored manures (mainly in the form of farmyard manure). Within buildings, poultry were the largest contributors of N2O, 2.97 kt, followed by cattle, 1.62 kt. Within the total emissions from stored manures, cattle were the largest contributors of N2O, 3.58 kt, followed by poultry, 1.86 kt. Dietary manipulation and a move from solid manure based systems to slurry based systems appear to be promising abatement practices.
Article
Agriculture contributes significantly to the anthropogenic emissions of non-CO2 greenhouse gases methane and nitrous oxide. In this paper, a review is presented of the agriculture related sources of methane and nitrous oxide, and of the main strategies for mitigation. The rumen is the most important source of methane production, especially in cattle husbandry. Less, but still substantial, amounts of methane are produced from cattle manures. In pig and poultry husbandry, most methane originates from manures. The main sources of nitrous oxide are: nitrogen fertilisers, land applied animal manure, and urine deposited by grazing animals. Most effective mitigation strategies for methane comprise a source approach, i.e. changing animals’ diets towards greater efficiencies. Methane emissions, however, can also be effectively reduced by optimal use of the gas produced from manures, e.g. for energy production. Frequent and complete manure removal from animal housing, combined with on-farm biogas production is an example of an integrated on-farm solution. Reduced fertiliser nitrogen input, optimal fertiliser form, adding nitrification inhibitors, land drainage management, and reduced land compaction by restricted grazing are the best ways to mitigate nitrous oxide emissions from farm land, whereas, management of bedding material and solid manure reduce nitrous oxide emissions from housing and storage. Other than for methane, mitigation measures for nitrous oxide interact with other important environmental issues, like reduction of nitrate leaching and ammonia emission. Mitigation strategies for reduction of the greenhouse gases should also minimize pollution swapping.
Article
A study was conducted to investigate the utilization of mature compost as a biofilter media for the removal of ammonia from the exhaust gases of the composting process. Source-selected organic fraction of municipal solid wastes, digested wastewater sludge and animal by-products were composted in a pilot-scale reactor and the exhaust gas was treated in a biofilter. Due to the high ammonia adsorption and absorption capacity of the compost media, no delay or start-up phase was observed and high removal efficiencies were achieved from the beginning of the experiments. A global ammonia removal efficiency of 95.9% was obtained in the biofilter for a loading rate range of 846–67,100 mg NH3 m−3 biofilter h−1. However, an important reduction of ammonia removal was observed when the waste gas contained high NH3 concentration (more than 2000 mg NH3 m−3), which corresponded with the case of animal by-products composting.
Article
A manure compost has been identified as an alternative to fertilizer to increase soil fertility and crop production in organic farming. The aim of the present study was to evaluate the effects of manure compost on soil properties and crop quality as well as to determine the optimum application rate. A field experiment was carried out to evaluate the growth of Brassica chinensis and Zea mays L. on loamy soil amended with 0, 10, 25, 50 and 75 tonnes ha−1 of manure compost. Addition of manure compost increased total organic matter, macro-nutrients (N, P, Mg, Na, Ca and K) and micro-nutrients (Cu, Zn and Mn) in the amended soils according to the rate of compost application. It also improved soil physical properties with a significant increase in soil porosity and hydraulic conductivity, but a decrease in bulk density. The dry weight yields of both plant species were higher in soils receiving manure compost amendment and plots with 50 and 25 tonnes ha−1 compost had the highest yields of Z. mays L. and B. chinensis, respectively. An increase in dry weight yields indicated a better nutrient status in compost-amended soil which was supported by the higher tissue nutrient contents of N, P and K of plants grown in soil with manure compost amendment. However, there was also a higher accumulation of Cu and Zn in plants growing in compost-amended soil. Nevertheless, the accumulated Cd contents were all within the concentrations recommended for vegetables by the National Health and Medical Research Council, Australia. It can be concluded that the manure compost produced locally could be a suitable organic fertilizer for organic farming in Hong Kong and an application rate of 25–50 tonnes ha−1 would give the highest crop yield.
Article
Evaluation of the mineralization dynamics of composted manures is essential for their efficient use as a major source of available nitrogen in crop production. The objective was to determine the effect of long-term management on the rate of mineralization of compost, in relation to soil biological activity. A compost was added at a rate of 5 or 15% (wt/wt) to soil samples obtained from two treatments of a 30 year old N-management experiment: M0—without any N input, and M2—with 10 applications of 90 t cattle manure ha−1. Inorganic N accumulation and weekly rates of CO2 evolution were determined periodically during an incubation of 33 weeks. Microbial counts and dehydrogenase and protease activity were determined during 42 days. Net N mineralization was higher in M2 than in M0 soil, and was proportional to the amount of compost added. The recovery of compost-N as inorganic N was independent of soil management history and of compost application rate. The amount of N released was estimated (by difference) to be 26% of compost N added. Initially 7–10% was inorganic N and 8% soluble organic N, therefore only 8–11% was released from insoluble N in the compost. CO2 evolution was greater from M2 than from M0 soil only during the first week, but it was significantly affected by compost application throughout the experiment. The percentage recovery of compost-C as CO2 was smaller at the high application rate. Microbial counts and enzyme activities exhibited a periodical behavior. They were significantly affected by soil management history, and by compost, but the effect of compost was greater. The difference in biological activity between soils seemed to be related to the difference in their initial readily-available C and it did not significantly affect the rate of compost decomposition.
Article
With an increase in using seawater, saline sewage is necessarily disposed of to protect the ocean. The objective in this work is to evaluate the effect of influent salinity and inhibition time on short-cut nitrogen removal from real domestic saline sewage, and to detect the performance of nitrifiers in activated sludge in SBR. Microbial tests are used to establish the mechanism of salt inhibition. Dynamic response of salt is recorded during and after the salt inhibition stage. As microbial population tests support that NOB is strongly inhibited below 1% (w/v) salt content, three different salt levels (0.52%, 0.76% and 1.02%) are applied respectively in three parallel SBRs for 60 days. Results reveal that NARs all increase by 95% and keep steady after the 15th, 7th and 2nd day by adding salt. Ammonia is almost totally degraded at the steady state at salt levels below 0.75%; however, it degrades nearly half at 1.02%. After stopping salt addition, the ARE in a 1.02% system reaches 94.3% at the 18th cycle and the SAURs all apparently increase. The NAR in 0.52% and 0.76% systems decreases at the 9th and 20th cycle but still keeps above 95% in the 1.02% system. In order to gain steady shot-cut nitrification in a SBR, conditions of salinity greater than 0.76% and salt inhibition for more than 60 days are very competitive and favorable for application.
Article
Nowadays, the drastic pollution problems, some of them related with greenhouse gas emissions, have promoted important attempts to face and diminish the global warming effects on the Mexico Valley Metropolitan Zone (MVMZ) as well as on the huge urban zones around the world. To reduce the exhaust gas emissions, many efforts have been carried out to reformulate fuels and design new catalytic converters; however, it is well known that other variables such as socio-economic and transport structure factors also play an important role around this problem. The present study analyzes the roles played by several commonly-used three-way catalytic converters (TWC) and the average traffic speed in the emission of N(2)O as greenhouse gas. According to this study, by increasing the average traffic flow and avoiding constant decelerations (frequent stops) during common trips, remarkable environmental and economic benefits could be obtained due to the diminution of N(2)O and other contaminant emissions such as ammonia (NH(3)) and even CO(2) with the concomitant reduced fossil fuel consumption. The actions mentioned above could be highly viable to diminish, in general, the global warming effects and contamination problems.
Article
Anaerobic digestion is an attractive waste treatment practice in which both pollution control and energy recovery can be achieved. Many agricultural and industrial wastes are ideal candidates for anaerobic digestion because they contain high levels of easily biodegradable materials. Problems such as low methane yield and process instability are often encountered in anaerobic digestion, preventing this technique from being widely applied. A wide variety of inhibitory substances are the primary cause of anaerobic digester upset or failure since they are present in substantial concentrations in wastes. Considerable research efforts have been made to identify the mechanism and the controlling factors of inhibition. This review provides a detailed summary of the research conducted on the inhibition of anaerobic processes. The inhibitors commonly present in anaerobic digesters include ammonia, sulfide, light metal ions, heavy metals, and organics. Due to the difference in anaerobic inocula, waste composition, and experimental methods and conditions, literature results on inhibition caused by specific toxicants vary widely. Co-digestion with other waste, adaptation of microorganisms to inhibitory substances, and incorporation of methods to remove or counteract toxicants before anaerobic digestion can significantly improve the waste treatment efficiency.
Article
The presence of ammonia nitrogen in landfill leachates poses a significant problem for treatment plant operators. The nitrification-denitrification process mostly carries out the nitrogen conversion in biological treatment systems. However, recent research shows that other processes by anaerobic ammonia-oxidizing bacteria (Anammox) and ammonia-oxidizing archaea (AOA) were also responsible for the removal of nitrogen in biological systems. In this study, the nitrogen-converting microorganisms in the Bursa Hamitler Leachate Treatment Plant were identified and monitored by using molecular tools. Fluorescent in situ hybridization (FISH) and slot-blot hybridization results showed that the Nitrosomonas and Nitrospira species were the dominant ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), respectively. Quantitative real-time PCR results indicated that AOB, NOB, AOA and Anammox bacteria exist in the leachate treatment plant. However, the removal of ammonia can be ascribed mainly to nitrification because AOB (1.5%) and NOB (11.3%) were predominant among all nitrogen-converting bacteria. The results of the phylogenetic analysis based on amoA and 16S rDNA gene revealed that the uncultured bacterium clone 4-24, Kuenenia stuttgartiensis genome fragment KUST_E and the uncultured Crenarchaeota clone NJYPZT-C1 belong to AOB, Anammox and AOA populations, respectively, and were the dominant species in their cluster.
Article
Animal manure is a significant source of environmental pollution and manure dilution in barn cleaning and slurry storage is a common practice in animal agriculture. The effect of swine manure dilution on releases of four pollutant gases was studied in a 30-day experiment using eight manure reactors divided into two groups. One group was treated with swine manure of 6.71% dry matter and another with manure diluted with water to 3.73% dry matter. Ammonia release from the diluted manure was 3.32 mg min(-1)m(-2) and was 71.0% of the 4.67 mg min(-1)m(-2) from the undiluted manure (P<0.01). Because the ammonia release reduction ratio was lower than the manure dilution ratio, dilution could increase the total ammonia emissions from swine manure, especially in lagoons with large liquid surface areas. Carbon dioxide release of 87.3 mg min(-1)m(-2) from the diluted manure was 56.4% of the 154.8 mg min(-1)m(-2) from the undiluted manure (P<0.01). Manure dry matter was an important factor for carbon dioxide release from manure. No differences were observed between the treatments (P>0.05) for both hydrogen sulfide and sulfur dioxide releases. Therefore, dilution could also significantly increase the total releases of hydrogen sulfide and sulfur dioxide to the environment because dilution adds to the total manure volume and usually also increases the total gas release surface area.
Article
Selective nitrification was carried out to accumulate nitrite from high strength ammonia wastewater in an autotrophic nitrifying biofilm reactor. Nitrification efficiencies and nitrite accumulation characteristics were investigated at various operating conditions such as ammonium load, oxygen supply and free ammonia concentration. The biofilm reactor showed very stable nitrification efficiencies of more than 90% at up to 2kgNH4-Nm-3 d-1 and the nitrite content was maintained at around 95%. Inhibition by free ammonia on nitrite oxidizers seems to be the major factor for nitrite accumulation. Batch kinetic analyses of ammonium and nitrite oxidation showed that nitrite oxidation activity was selectively inhibited in the presence of free ammonia. However, the activity recovered quickly as the free ammonia concentration decreased below the threshold inhibition concentration. Examination of specific ammonia and nitrite oxidation activities and the most probable number indicated that the number of nitrite-oxidizing microorganisms in the nitrite-accumulating system was less than that in the normal nitrification system due to long-term free ammonia inhibition of the nitrite oxidizers. The reduced population of nitrite oxidizers in the biofilm system was also responsible for the accumulation of nitrite in the biofilm reactor.
Article
The effect of physical-chemical slurry treatment on the mobility and transformation of nitrogen and organic matter from pig slurry after soil application is evaluated. Two different pig slurries (one treated by stripping with air at pH=9 and another non-treated) were applied at the top of a soil column, containing approximately 100 kg of soil. Effluents were monitored measuring concentration values of ammonia, nitrites, nitrates and total organic carbon (TOC). The breakthrough curves were modelled using STANMOD and HYDRUS 1D codes. Low concentrations of ammonia were detected in the effluent recovered at the bottom of the soil profile for both types of slurry. Nitrate concentration in effluent was lower and more homogenous over time when applying stripping treated pig slurry. In N modelling, adsorption of ammonia by soil proved an important process, nitrite and nitrate adsorption being less significant, although not negligible. Transformation from ammonia to nitrite controls the kinetics of the nitrification process. Total organic carbon in the column effluent was higher in the experiment using treated pig slurry, which can be attributed to organic matter solubilisation in the stripping treatment process.
Article
Henry’s law constants (solubilities) of trace gases of potential importance in environmental chemistry (atmospheric chemistry,waste water treatment, . . . ) have been collected and converted into a uniform format.
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Abstract Nitrobacter, a ubiquitous nitrite oxidizer in natural and anthropized environments, is commonly studied as the model genus performing the second stage of nitrification. In rivers, wastewater treatment plant discharges may affect the nitrite-oxidizing activity and the responsible genera that are largely associated with sediment. We used a laboratory batch culture approach with Nitrobacter wynogradskyi ssp. agilis strain AG and Nitrobacter hamburgensis strain X(14) to characterize the possible stress effect of wastewater effluent on these populations and to study the possible competition between an effluent strain (X(14)) and a sediment strain (AG) over a 42-day incubation time. Immunofluorescence enumerations of each strain showed that they both survived and settled in the sediment, indicating that there was no significant stress effect due to chemical changes caused by the effluent. The development of the strains' density and activity was directly correlated with the available nitrite concentration. Nevertheless, the potential specific activity was not constant along the so-called mixotrophic (non-limiting nitrite concentration) and heterotrophic (nitrite depletion) conditions. This illustrates the inducibility of the nitrite oxidoreductase and indicates the metabolic versatility of the strains. In our experimental conditions, the preferentially autotrophic AG strain appeared more competitive than the preferentially mixo- or heterotrophic X(14) strain, including in heterotrophic environment.
Article
Biological removal of ammonia was investigated using compost and sludge as packing materials in laboratory-scale biofilters. The aim of this study is to characterize the composition of ammonia-oxidizing bacteria (AOB) in two biofilters designed to remove ammonia. Experimental tests and measurements included analysis of removal efficiency and metabolic products. The inlet concentration of ammonia applied was 20-100 mg m(-3). Removal efficiencies of BFC and BFS were in the range of 97-99% and 95-99%, respectively. Periodic analysis of the biofilter packing materials showed ammonia was removed from air stream by nitrification and by the improved absorption of NH(3) in the resultant acidity. Nitrate was the dominant product of NH(3) transformation. Changes in the composition of AOB were examined by using nested PCR, denaturing gradient gel electrophoresis (DGGE) and sequencing of DGGE bands. DGGE analysis of biofilter samples revealed that shifts in the community structure of AOB were observed in the experiment; however, the idle phase did not cause the structural shift of AOB. Phylogenetic analysis revealed the population of AOB showed Nitrosospira sp. remains the predominant population in BFC, while Nitrosomonas sp. is the predominant population in BFS.
Article
Intensification of animal production led to high amounts of manure to be managed. Biological processes can contribute to a sustainable manure management. This paper presents the biological treatments available for the treatment of animal manure, mainly focusing on swine manure, including aerobic processes (nitrification, denitrification, enhanced biological phosphorus removal) and anaerobic digestion. These processes are discussed in terms of pollution removal, ammonia and greenhouse gas emissions (methane and nitrous oxide) and pathogen removal. Application of emerging processes such as partial nitrification and anaerobic ammonium oxidation (anammox) applied to animal manure is also considered. Finally, perspectives and future challenges for the research concerning biological treatments are highlighted in this paper.
Article
Anthropogenic nitrous oxide (N2O) emissions from Europe, and Asiatic Turkey, are estimated for the period 1960-2040. Between 1960 and 1985 these emissions are found to have doubled to 1059 kton N2O-N/year. For future emissions three scenarios are defined: a no reduction scenario, where current trends continue; an acid reduction scenario, reflecting the implementation of maximum feasible technology to reduce acidification; and an optimistic scenario, in which both N2O and acidifying emissions are strongly reduced. In the no reduction and acid reduction scenario anthropogenic N2O emissions increase to 1199 and 1274 kton N2O-N/year by 2040, respectively. Thus technologies to reduce acidification are calculated to cause a net increase in N2O emissions. In the optimistic scenario 534 kton N2O-N is emitted annually from 2020. A climate goal, aiming to limit future global warming to 0.1 degree C//decade, is calculated to require a stabilization of anthropogenic European emissions at 221 kton N2O-N/year (based on a pro rata contribution of greenhouse gases to emission reductions, and worldwide equal per capita N2O emissions). In all three scenarios N2O emissions exceed 221 kton N2O-N/year. In order to meet their goal, countries need to cut anthropogenic emissions by 59-90% relative to 1985, and by 40-63% relative to 2040 in the optimistic scenario.
Article
The microbial community in sludge-treated and nearby untreated soils was investigated using direct microscopic counting, plate culture, carbon substrate utilisation (Biolog), and fatty acid methyl esters. Long-term sewage sludge applications had resulted in higher concentrations of organic carbon and had altered other factors in the soil, including the concentration of metals. Bioluminescence was inhibited in assays of the sludge-treated soil, although microbial counts were similar in all soils. A detailed analysis of carbon substrate utilisation patterns and fatty acid methyl esters showed qualitative differences in the microbial populations. This work shows that a variety of approaches are required to assess microbial communities in soil where, despite large differences in land management, the populations are similar in size and overall composition.