Anaerobic Digestion Of Livestock Manure Research Articles

Characterizing and modeling hydrogen sulfide production in anaerobic digestion of livestock manure, agro‐industrial wastes, and wastewater sludge

AbstractHydrogen sulfide (H2S) is the most undesirable inorganic gas in biogas from anaerobic digestion (AD). However, H2S production in AD is complex and understanding of its processes is still limited. This study performed six controlled batch anaerobic co‐digestion experiments to investigate H2S production. Materials were obtained from four field anaerobic digester systems and co‐digestion feedstocks from agroindustry. An additional precipitation experiment was conducted to further examine H2S production dynamics. Digesters containing highly soluble, carbohydrate‐based wastes had a high H2S final specific production (FSP) value. Additionally, the FSP values were negatively correlated with the initial Fe(II):S ratios in the digester liquid of the batch tests. The precipitation experiment indicated that iron sulfide precipitation was preferred in the presence of an anaerobic community. The H2S production as a time series was successfully modeled using a generalized additive model (R2 > 0.82). This study revealed that sulfate, phosphorus, and iron concentrations are important predictors and potential inhibitors of H2S production in AD. Further examination of real‐time H2S modeling in AD is warranted.

Organic contaminants removal and carbon sequestration using pig manure solid residue-derived biochar: A novel closed-loop strategy for anaerobic liquid digestate

Anaerobic digestion of livestock manure as a carbon-negative practice yields bioenergy and biofertilizer. However, substantial antibiotics and benzenes contained in liquid and solid digestate hinder its large-scale applications. In this study, a novel closed-loop treatment strategy was proposed to integrate the synthesis benefits of anaerobic digestion, pyrolysis of solid digestate, and adsorption. The solid digestate-derived biochar (S-biochar) was successfully prepared by coupling pyrolysis and H2SO4 activation. The S-biochar possessed a polycyclic aromatic structure, abundant micropores (0.8–1.0 nm), various functional groups (–COOH, Aro–OH), and a higher absolute zeta potential value. These characteristics contributed to the excellent adsorption of tetracycline (51.3 mg/L), oxytetracycline (32.9 mg/L), benzene (86.0 mg/L) and toluene (74.1 mg/L), wherein pore filling, electrostatic interactions, H-bonding, surface partition, and π-π conjugation mechanisms were involved. The adsorption of antibiotics was more sensitive to pH, in comparison with benzenes, and displayed a declining trend (pH>7). Under actual liquid digestate conditions, >95% adsorption of antibiotics and benzenes were reached at the dosage of 1.5 g/L, in a company with >80% of nitrogen and phosphorus. In the end, a carbon and nitrogen flow analysis was performed to elucidate that more than 80% of carbon in pig manure can be settled as biochar and biogas, and up to 94.7% of nitrogen remained in the biochar and liquid digestate. This study not only developed a S-biochar with excellent performance in removing organic pollutants from liquid digestate, but also established a closed-loop strategy as an alternative carbon sequestration approach using anaerobic digestion side-products.

Changes in bacterial diversity, co-occurrence pattern, and potential pathogens following digestate fertilization: Extending pathogen management to field for anaerobic digestion of livestock manure

Digestate can spread pathogens into agroecosystem, posing serious threats to public health. However, the effect of digestate fertilization on digestate- or soil-borne pathogens has not been fully explored. Herein, two settings of microcosm experiment were performed with arable soil and digestate collected at two sites (Beilangzhong or Shunyi) to dissect the succession of the total and potential pathogenic bacterial communities following digestate fertilization. Each experimental setting consisted of three treatments, including digestate aerobically incubated in sterilized soil, and soil amended with sterilized or non-sterilized digestate. Digestate-borne potential pathogenic bacteria were enriched after the aerobic incubation, with Streptococcus sobrinus in the Beilangzhong setting, and Escherichia coli and Enterococcus faecium in the Shunyi setting. Potential soil-borne pathogenic bacteria, such as Acinetobacter lowffii and Pseudomonas fluorescens, were stimulated by the sterilized digestate in the Shunyi setting. Interestingly, S. sobrinus, E. coli, and Ent. faecium did not increase when digestate was amended into the non-sterilized soil, suggesting that soil microorganisms can inhibit the resurgence of these digestate-borne pathogens. A large-scale survey further revealed that organic fertilization exerted a site-dependent effect on different species of potential pathogen, but it did not enrich the total relative abundance of potential pathogenic bacteria in soils. Collectively, these results highlight that pathogen management of anaerobic digestion of livestock manure needs to be extended from anaerobic reactor to field.

Evaluation of Non-Biodegradable Organic Matter and Microbial Community’s Effects on Achievement of Partial Nitrification Coupled with ANAMMOX for Treating Low-Carbon Livestock Wastewater

After the anaerobic digestion of livestock manure, high concentrations of nutrients still remain. Treatment of livestock wastewater through partial nitrification coupled with anaerobic ammonium oxidation (ANAMMOX) could be a useful technology depending on the investigation of microorganism enrichment and partial nitrification coupled with achievement of the ANAMMOX process. The results show 78.4% and 64.7% nitrite accumulation efficiency was successfully obtained in an intermittent aeration sequencing batch reactor and a continuous aeration sequencing batch reactor, respectively, at a loading rate of 0.93 kg ammonium/(m3·d). The main reason for the high nitrite accumulation efficiency was the intermittent aeration strategy which generated a 20–30 min lag reaction for nitrite oxidation and promoted the growth of the dominant ammonium oxidation bacteria (Nitrosomonas). Non-biodegradable organic matter in the effluents of partial nitrification did not have obvious influence on ANAMMOX activity at low loading rates (118 ± 13 mg COD/L and 168 ± 9 mg COD/L), and up to 87.4% average nitrite removal rate was observed. However, with the influent COD concentration increasing to 242 ± 17 mg/L, the potential inhibition of ANAMMOX activity was exerted by non-biodegradable organic matter.

Inorganic additives to increase methane generation during anaerobic digestion of livestock manure: a review

Recycling livestock manure provides energy and prevent pollution, yet actual transformation processes are limited in terms of performance and cost. Here, we review inorganic additives used to improve anaerobic digestion. Additives include minerals such as zeolite and magnetite, metals such as bulk and nanoparticles, industrial wastes, and pH-regulating additives. We focus on microbial mechanisms in terms of microbial growth, enzymes, interspecies electron transfer and microbial community, instead of the often reported physico-chemical mechanisms. Porous additives such as zeolites are well suited to removing ammonium. Iron-based metal additives are highly influencing microbial mechanisms.

Environmental impacts concerning the addition of trace metals in the process of biogas production from anaerobic digestion of slurry

Abstract The use of trace metals as additives to the biogas production process to increase the biogas yield has been identified as a very common approach. Such additives can biostimulate the methanogenic bacteria to increase the biogas and methane production from the anaerobic digestion (AD) of livestock manure. The environmental impact of using the trace elements as manure additives still not evaluated. The objective of this paper is to conduct a comparative environmental impact evaluation of manure treatment with different trace elements for biogas production. The trace metals under evaluation were in the form of the chlorides of nickel (Ni), cobalt (Co) and iron (Fe) which were used as additives to the anaerobic digestion of livestock manure. The results were shown in the form of the specific impacts on global warming and greenhouse gas (GHG) emissions mitigation of producing and utilizing biogas as a bioenergy source. The results of this investigation show that the use of 1 g/m3 cobalt chloride (CoCl2) causes the lowest greenhouse gas emissions among all other evaluated trace metals which were calculated on the basis of CO2-equivalent. An important observation is that the greenhouse gas emissions from the electricity generated using biogas produced without any additives, i.e. without trace metals, were the highest among all other variants/scenarios.

A Study on VS Removal Efficiency and Methane Emission in Combined Anaerobic Digestion of Livestock Manure and Food Waste

Livestock manure treatments have become a more serious problem because massive environmental pollutions such as green and red tides caused by non-point pollution sources from livestock manures have emerged as a serious social issue. In addition, more food wastes are being produced due to population growth and increased income level. Since the London Convention has banned the ocean dumping of wastes, some other waste treatment methods for land disposal had to be developed and applied. At the same time, researches have been conducted to develop alternative energy sources from various types of wastes. As a result, anaerobic digestion as a waste treatment method has become an attractive solution. In this study has three objectives: first, to identify the physical properties of the mixture of livestock wastewater and food waste when combining food waste treatment with the conventional livestock manure treatment based on anaerobic mesophilic digestion; second, to find the ideal ratio of waste mixture that could maximize the collection efficiency of methane (CH4) from the anaerobic digestion process; and third, to promote CH4 production by comparing the biodegradability. As a result of comparing the reactors R1, R2, and R3, each containing a mixture of food waste and livestock manure at the ratio of 5:5, 7:3, and 3:7, respectively, R2 showed the optimum treatment efficiencies for the removal of Total Solids (TS) and Volatile Solids (VS), CH4 production, and biodegradability.

The Valorization of Ammonia in Manure Digestate by Means of Alternative Stripping Reactors

The proper recovery of resources such as nitrogen and phosphorus present in the manure from intensive livestock farming is essential in order to allow environmental sustainable zootechny especially in densely populated areas where these activities are historically prevalent. The experiences at full-scale established that the ammonia stripping allows recovery from 35% to 50% of nitrogen depending on the type of substrate treated with anaerobic digestion and on the nitrogen content/form in the digestate. This study focuses on the ammonia stripping on digestate derived from anaerobic digestion of livestock manure and corn silage. Two different full-scale plants are studied including a packed column and an air bubble reactor without filling material with the aim to reduce fouling issues due to the content of suspended solids in digestate. The main results suggest that the use of an air bubble reactor could treat digestate with high concentration of suspended solids. A deeper study based on a two-level factorial experiment highlights that the temperature is an important parameter that influences the ammonia removal yields. Thus, a proper management of available thermal energy is very important.

Nutrient Recovery from Digestate of Anaerobic Digestion of Livestock Manure: a Review

Animal manure is often anaerobically digested for the purpose of producing biogas. The digested manure, namely digestate, can be applied onto farmlands to enhance crop yields as it is abundant in nutrients. However, intensive livestock farming brings about manure exceeding the carrying capacity of lands nearby. Technologies focused on nutrient recovery from digestate have been studied recently, while many problems and challenges still remain unsolved. In this article, these recovery technologies are reviewed and compared, and challenges are deliberated. Ammonia stripping and struvite formation are easily operated technologies in comparison with membrane technologies. Amongst membrane technologies, electrodialysis reversal and forward osmosis are promising due to their high resistance to membrane fouling. Further studies should be focused on the operational cost, disposal of solid and liquid residuals and marketization of the recovered products.

Evaluation of biogas potential from livestock manures and rural wastes using GIS in Iran

Abstract The increasing demand of energy, fossil resource limitation and environmental pollution due to fuels combustion has motivated researchers to study about renewable sources of energies. Biogas is a renewable energy resource which is produced through decomposing organic waste under anaerobic conditions and is mainly composed of methane (60%) and carbon dioxide (35–40%). Anaerobic digestion of livestock manure and rural waste, which need to be managed properly to prevent pollution, can be used for sustainable biogas production, reduction of unpleasant odors and microbial pathogens and production of rich fertilizers. This study addresses on how utilization of information such as rural and livestock population, land-use maps and geographic information system (GIS) can be employed to develop a model for evaluation of biogas production from livestock manure and rural household waste, in Iran. The model can be used to identify the appropriate locations for construction of biogas production plants. Moreover, the analysis process used in the current study relies on more spatially detailed information about the available biomass and suitable sites for biogas plant construction, compared to the previous studies conducted in Iran. The results showed that 2740 million m3/year of methane can be annually produced using livestock manure and rural wastes.

Nitrogen removal from digested slurries using a simplified ammonia stripping technique

This study assessed a novel technique for removing nitrogen from digested organic waste based on a slow release of ammonia that was promoted by continuous mixing of the digestate and delivering a continuous air stream across the surface of the liquid. Three 10-day experiments were conducted using two 50-L reactors. In the first two, nitrogen removal efficiencies were evaluated from identical digestates maintained at different temperatures (30°C and 40°C). At the start of the first experiment, the digestates were adjusted to pH 9 using sodium hydroxide, while in the second experiment pH was not adjusted. The highest ammonia removal efficiency (87%) was obtained at 40°C with pH adjustment. However at 40°C without pH adjustment, removal efficiencies of 69% for ammonia and 47% for total nitrogen were obtained. In the third experiment two different digestates were tested at 50°C without pH adjustment. Although the initial chemical characteristics of the digestates were different in this experiment, the ammonia removal efficiencies were very similar (approximately 85%). Despite ammonia removal, the pH increased in all experiments, most likely due to carbon dioxide stripping that was promoted by temperature and mixing. The technique proved to be suitable for removing nitrogen following anaerobic digestion of livestock manure because effective removal was obtained at natural pH (≈8) and 40°C, common operating conditions at typical biogas plants that process manure. Furthermore, the electrical energy requirement to operate the process is limited (estimated to be 3.8kWhm−3digestate). Further improvements may increase the efficiency and reduce the processing time of this treatment technique. Even without these advances slow-rate air stripping of ammonia is a viable option for reducing the environmental impact associated with animal manure management.

Effect of the long-term application of anaerobically digested residual slurry on methane emissions in a rice paddy field

ABSTRACTThe anaerobic digestion of livestock manure is an environmentally compatible technology used for the production of renewable energy. Anaerobically digested residual slurry has been used worldwide as a liquid fertilizer in both upland and paddy fields. However, a controversial question remains as to whether the application of slurry to rice paddy fields increases methane emissions; although methane is one of the most prevalent greenhouse gases, little is known about the effects of the long-term application of residual slurry on methane emission. In this study, we repeatedly applied slurry to a paddy field for six years at different application rates (10, 15, and 20 g N m−2 based on ammonium-nitrogen content). At the fifth and sixth years of application, we evaluated the effect in terms of methane flux and soil total carbon content. The effect of the long-term application of the slurry (10 g N m−2) on grain yield was equivalent to that of chemical fertilizer (10 g N m−2). The application of the residual slurry was likely to increase the cumulative methane emissions during rice growing season in both 2006 and 2007. On the other hand, we observed that soil total carbon did not accumulate significantly in the soil. Thus, we cannot rule out the potential risk of additional methane emissions caused by the application of the residuary slurry to paddy fields.

Comparison of nanoparticles effects on biogas and methane production from anaerobic digestion of cattle dung slurry

Nanoparticles (NPs) of trace metals such as Co, Ni, Fe and Fe3O4 were implemented in this study to compare their effects on biogas and methane production from anaerobic digestion of livestock manure. The most effective concentrations of NPs additives were determined based on our previous studies, and were 1 mg/L Co NPs, 2 mg/L Ni NPs, 20 mg/L Fe NPs and 20 mg/L Fe3O4 NPs. These concentrations of NPs additives were further investigated and compared to each other in this study and were found to significantly (p < 0.05) increase the biogas yield by 1.7, 1.8, 1.5 and 1.7 times in comparison with control, respectively. The methane yield significantly (p < 0.05) increased by 2, 2.17, 1.67 and 2.16 times the methane volume of the control, respectively. The results of this study showed that the Ni NPs yielded the highest biogas and methane production compared to Co, Fe and Fe3O4 NPs.

Understanding Nitrogen Availability from Applications of Anaerobically Digested Beef-Cattle Manure in Florida Sandy Soil

Anaerobic digestion of livestock manure is a microbe-mediated process carried out in vessels or tanks, where the livestock wastes are digested slowly in environment absent of oxygen. The main products are biogas, anaerobically digested liquid (ADL), and solid (ADS), which can be land-applied as an organic soil amendment or a source of plant nutrients. This 4-page fact sheet provides research-based information about using anaerobically digested beef-cattle manure as an organic source of nitrogen for supplementing crop nutrition in Florida sandy soils, including initial N concentration, application timing, rate of application, and method of application. Written by Rishi Prasad and George Hochmuth, and published by the UF Department of Soil and Water Science, April 2015. (Photo: George Hochmuth, UF/IFAS)&#x0D; SL424/SS637: Understanding Nitrogen Availability from Applications of Anaerobically Digested Beef-Cattle Manure in Florida Sandy Soil (ufl.edu)

Evaluation of the properties and the papermaking applicability of the residue originated from the anaerobic digestion of livestock manure

Management of organic waste such as livestock manure has been considered as very important issue in terms of the environment. The anaerobic digestion of livestock manure become more attractive treatment method and has been widely applied. In this work, the properties of the residue after the anaerobic digestion of livestock manure was evaluated for providing the basic data to develop new application. The lignin and the ash contents of the residue were much higher than those of other biomass such as wood. The components of the residue were also analyzed with SEM-EDS and Elemental Analyzer. The addition of the residue into the handsheet paper resulted in the higher bulk and he higher air permeability with the loss of the strength properties. The water holding capacity of the handsheet were increased until the 40 % addition of the residue.

Evaluating the toxicity of food processing wastes as co-digestion substrates with dairy manure

Studies have shown that including food waste as a co-digestion substrate in the anaerobic digestion of livestock manure can increase energy production. However, the type and inclusion rate of food waste used for co-digestion need to be carefully considered in order to prevent adverse conditions in the digestion environment. This study determined the effect of increasing the concentration (2%, 5%, 15% and 30%, by volume) of four food-processing wastes (meatball, chicken, cranberry and ice cream processing wastes) on methane production. Anaerobic toxicity assay (ATA) and specific methanogenic activity (SMA) tests were conducted to determine the concentration at which each food waste became toxic to the digestion environment. Decreases in methane production were observed at concentrations above 5% for all four food waste substrates, with up to 99% decreases in methane production at 30% food processing wastes (by volume).

Nonmarket cobenefits and economic feasibility of on-farm biogas energy production

Standard analysis of the economic feasibility of on-farm biogas energy production tend to emphasize primarily on direct financial benefits to farmers, and abstracts from the nonmarket cobenefits associated with anaerobic digestion of livestock manure and other biomass feedstock. This shortcoming of the standard feasibility analysis raises a fundamental question: How is the economic feasibility of on-farm anaerobic biogas energy production affected by the associated nonpecuniary cobenefits? Incorporating key nonmarket cobenefits from biogas energy production extends the standard economic feasibility analysis, and provides important insights. When nonmarket cobenefits were excluded, on-farm biogas energy production was generally not financially feasible for the dairy and swine farm size ranges studied (except for 600- and 800-sow farms). Overall, results of the financial feasibility analysis did not change compared to a base scenario (without nonmarket cobenefits) when an estimated annual total nonmarket cobenefits of CND$5000 was incorporated into the analysis, for both dairy and swine farms. Biogas energy production was generally financially viable for small-size dairy (i.e., 50-cow) and swine (i.e., 200-sow) farms when the nonmarket cobenefits were valued at CND$15,000 (or higher). Improvements in financial feasibility were more dramatic for dairy than for swine farms.

Impact of single versus multiple policy options on the economic feasibility of biogas energy production: Swine and dairy operations in Nova Scotia

The economic feasibility of on-farm biogas energy production was investigated for swine and dairy operations under Nova Scotia, Canada farming conditions, using net present value (NPV), internal rate of return (IRR), and payback period (PP) economic decision criteria. In addition, the effects of selected environmental and “green” energy policy schemes on co-generation of on-farm biogas energy production and other co-benefits from anaerobic digestion of livestock manure were investigated. Cost-efficiencies arising from economies of scale for on-farm anaerobic biogas production were found for swine farms, and less so for dairy production systems. Without incentive schemes, on-farm biogas energy production was not economically feasible across the farm size ranges studied, except for 600- and 800-sow operations. Among single policy schemes investigated, green energy credit policy schemes generated the highest financial returns, compared to cost-share and low-interest loan schemes. Combinations of multiple policies that included cost-share and green energy credit incentive schemes generated the most improvement in financial feasibility of on-farm biogas energy production, for both swine and dairy operations.

Kinetic Model for Anaerobic Digestion of Livestock Manure

Two unstructured segregated kinetic models to describe the anaerobic digestion of livestock manure are developed and experimental batch data obtained from beef cattle in a 2.0-l work volume digestor fitted to both proposed kinetic models to obtain the values of the parameters. The results obtained by fitting show that the second model proposed has both statistical and physical meaning in the parameter values obtained. The model takes into account a simplified reaction scheme formed by six reactions. Several simplifications have been made (lumping, pseudo-steady state for one compound, first order kinetics, etc.) yielding four key compounds to be analysed and fitted to the model as production-rates expressions (total biomass, chemical oxygen demand (COD), volatile acids, and methane). The model considers three main stages in the process: enzymatic hydrolysis of the waste, growth of ‘acetogenic’ microorganisms (production of acids nongrowth associated), and growth of ‘methanogenic’ microorganisms associated with methane production; the two last processes are accompanied by substrate consumption for maintenance. A non-linear multiple-response regression technique coupled to a fourth-order Runge–Kutta algorithm has been employed to obtain the values of the ten parameters. The model is able to reproduce the experimental data obtained for beef manure anaerobic digestion with more accuracy than experimental error.