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Simple Summary: This study investigates the impact of iron oxide (Fe3O4) nanoparticles on the anaerobic digestion (AD) of frass, a by-product of black soldier fly (BSF) larvae bioconversion of swine manure, and its co-digestion with corn straw. The aim is to enhance biogas production, particularly during the inoculum-free start-up phase of the AD process. Results indicate that the incorporation of Fe3O4 nanoparticles, especially those of ~184 nm size, significantly boosts average biogas yields, with a notable increase in methane production compared to control groups. The methanogenic analysis reveals that species such as Methanocorpusculum, Methanosarcina, and Methanomassiliicoccus play crucial roles in the AD reactor, with the ~184 nm group demonstrating optimal microbial diversity, potentially accounting for its superior gas output. The findings contribute to the advancement of renewable energy generation, sustainable development, and environmental conservation by providing a scientific basis for improving the efficiency of biogas production from organic waste. With the increasing prominence of the global energy problem, socioeconomic activities have been seriously affected. Biofuels, as a renewable source of energy, are of great significance in promoting sustainable development. In this study, batch anaerobic digestion (AD) of frass (swine manure after bioconversion by black soldier fly larvae) and co-digestion with corn straw after the addition of iron oxide (Fe3O4) nanoparticles is investigated, as well as the start-up period without inoculation. The biochemical methane potential of pure frass was obtained using blank 1 group and after the addition of various sizes of Fe3O4 nanoparticles for 30 days period, and similarly, the digestion of frass with straw (blank 2) and after the addition of various sizes of Fe3O4 nanoparticles for 61 days period. The results showed that the average gas production was 209.43 mL/gVS, 197.68 mL/gVS, 151.85 mL/gVS, and 238.15 mL/gVS for the blank, ~176 nm, ~164 nm, and ~184 nm, respectively. The average gas production of frass with straw (blank 2) was 261.64 mL/gVS, 259.62 mL/gVS, 241.51 mL/gVS, and 285.98 mL/gVS for blank 2, ~176 nm, ~164 nm, and ~184 nm, respectively. Meanwhile, the accumulated methane production of the ~184 nm group was 2312.98 mL and 10,952.96 mL, respectively, which significantly increased the biogas production compared to the other groups. The methanogenic results of the frass (30 days) indicated that Methanocorpusculum, Methanosarcina, and Methanomassiliicoccus are the important methanogenic species in the AD reactor, while the microbial diversity of the ~184 nm group was optimal, which may be the reason for the high gas production of ~184 nm. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of animal manure generates biogas and removes biodegradable organic matter, while most of the nitrogen and phosphorous remains at very high levels after the process. A subsequent microalgae culture in the digestate provides nutrient uptake at very low operational and installation costs. However, the dark color of manure digestate prevents light penetration, reducing the rates of algae growth. Ozonation was researched as a strategy for color removal followed by microalgae culture. Although similar biomass production was achieved in treated and untreated digestates (1.09 vs. 0.99 g L−1), the positive effect of ozonation was evidenced by the significantly higher rates of photosynthetically produced oxygen: 0.804 and 0.18 mg O2 mg−1 TSS min−1, respectively, in ozonated and untreated digestates, revealing a four times higher rate of algae activity. However, this considerable higher activity was not correlated with better performance in nutrient removal since the microalgae treatment was assayed at a considerably reduced scale with a high ratio of illumination per volume. An operational costs analysis revealed that ozonation could be competitive against other strategies of color reduction such as dilution or coagulation/flocculation processes. [ABSTRACT FROM AUTHOR]

To meet Colombia's energy needs by 2050, a total installed capacity of 42 MW across its power generation infrastructure is required. To achieve this, transitioning to cleaner energy sources, such as biomass—a non-conventional renewable energy—is necessary. Biomass is a promising renewable source for thermal and electrical energy production. This study researched the production of biogas from swine manure using a UASB reactor to valorize this waste. Swine manure was collected every 20 days from a pig farm with a capacity of 200 sows, located in Santa Rosa de Osos, Antioquia. The flow rate was increased three times (1.30 L d−1, 1.62 L d−1, and 2.08 L d−1) to reduce the hydraulic retention time (HRT) and enhance biogas production. The volatile and total solids, chemical oxygen demand (COD), alkalinity, and biogas composition were measured over one year. The proposed system achieved 87.40% COD remotion from the feed stream and generated a yield of 507 mLCH4 gVS−1, with an HRT of 19 days and an OLR of 4.27 gCOD L−1 d−1. The reactor produced biogas with a CH4 content of 67.7%, CO2 content of 18.1%, and H2S content of 1413 ppm. This study highlights the effectiveness of the UASB reactor for biogas production using swine manure as a substrate. [ABSTRACT FROM AUTHOR]

Using swine manure biochar and biogas slurry in agriculture proves to be an effective strategy for soil improvement and fertilization. In this study, a pot trial on the growth of lotus root was conducted to investigate the persistent effects of applying 350°C swine manure biochar (1% and 2%) and biogas slurry (50% and 100%) on soil nitrogen nutrient and lotus root quality. The results showed that compared to chemical fertilizer alone (A0B0), swine manure biochar significantly increased soil nitrogen content after one year of application. The contents of total nitrogen (TN), alkali-hydrolyzed nitrogen (AHN), ammonium nitrogen (NH4 + −N) increased by 17.96% to 20.73%, 14.05% to 64.71%, 17.76% to 48.68% and 2.22% to 8.47%, respectively, during the rooting period. When swine manure biochar was present, the application of biogas slurry further elevated soil nitrogen content. The co-application of swine manure biochar and biogas slurry significantly increased soil nitrogen content, and the 100% nitrogen replacement with biogas slurry combined with 2% swine manure biochar (A2B2) treatment exhibited the most significant enhancement effect during whole plant growth periods. Soil enzyme activities, including soil protease (NPT), leucine aminopeptidase (LAP), b-glucosidase (β-GC) and dehydrogenase (DHA), showed a tendency to increase and then decrease with the prolongation of lotus root fertility period, reaching the maximum value during the rooting period. Compared to A0B0, the treatment with 2% swine manure biochar had the most significant effect on enzyme activities and increased the lotus root’s protein, soluble sugar, and starch contents. Nitrate content decreased with the application of 2% swine manure biochar as the amount of biogas slurry increased. In conclusion, swine manure biochar effectively improved soil nitrogen content, enzyme activity, and lotus root quality. Even after one year of application, 2% swine manure biochar had the best enhancement effect. [ABSTRACT FROM AUTHOR]3− −N) increased by 17.96% to 20.73%, 14.05% to 64.71%, 17.76% to 48.68% and 2.22% to 8.47%, respectively, during the rooting period. When swine manure biochar was present, the application of biogas slurry further elevated soil nitrogen content. The co-application of swine manure biochar and biogas slurry significantly increased soil nitrogen content, and the 100% nitrogen replacement with biogas slurry combined with 2% swine manure biochar (A2B2) treatment exhibited the most significant enhancement effect during whole plant growth periods. Soil enzyme activities, including soil protease (NPT), leucine aminopeptidase (LAP), b-glucosidase (β-GC) and dehydrogenase (DHA), showed a tendency to increase and then decrease with the prolongation of lotus root fertility period, reaching the maximum value during the rooting period. Compared to A0B0, the treatment with 2% swine manure biochar had the most significant effect on enzyme activities and increased the lotus root’s protein, soluble sugar, and starch contents. Nitrate content decreased with the application of 2% swine manure biochar as the amount of biogas slurry increased. In conclusion, swine manure biochar effectively improved soil nitrogen content, enzyme activity, and lotus root quality. Even after one year of application, 2% swine manure biochar had the best enhancement effect. [ABSTRACT FROM AUTHOR]

Introduction: In Cuba, there is a tendency to decentralize productions with the creation of livestock modules where different livestock species coexist, such as swine, cattle and poultry. In this context, anaerobic digestion (AD) is an alternative for the decarbonization of the agricultural sector, since it generates energy during waste treatment. Objective: To evaluate the AD of swine manure (SM) and poultry manure (PM) with cattle manure (CM) in terms of biochemical methane potential (BMP), and kinetic parameters in mono and co-digestion. Materials and Methods: The trial was conducted in 2 L reactors at 27 °C (average). The BMP of SM, PM and CM was determined in mono-digestion, and then with addition of 15, 30 and 45 % of CM, to the PM40:SM60 mixture. To describe the kinetic behavior of the process, experimental data were fitted to three first and second order models. Results and Discussion: The experimental BMP with CM addition was higher than expected, with increase between 26-31 %, demonstrating the synergy of the mixtures; since the C/N ratio and the methanogenic archaeal community were improved. The models were adjusted to the experimental data with adjusted coefficients of determination higher than 90 %. Conclusions: The addition of CM increased the experimental methane yield over the expected one. The Hill model shows a maximum yield of 369 LCH4/kgVS for mixtures with 15 and 30 % CM. The best variant was with 15 %, and it is necessary to transport manure from 20 cows to the biodigester. [ABSTRACT FROM AUTHOR]

The main purpose of this paper is the techno-economic analysis of hydrogen production from biogas via steam reforming in a pilot plant. Process flow modeling based on mass and energy balance is used to estimate the total equipment purchase and operating costs of hydrogen production. The pilot plant installation produced 250.67 kg/h hydrogen from 1260 kg/h biomethane obtained after purification of 4208 m3/h biogas using a heat and mass integration process. Despite the high investment cost, the plant shows a great potential for biomethane reduction and conversion to hydrogen, an attractive economic path with ecological possibilities. The conversion of waste into hydrogen is a possibility of increasing importance in the global energy economy. In the future, such a plant will be expanded with a CO2 reduction module to increase economic efficiency and further reduce greenhouse gases in an economically viable manner. [ABSTRACT FROM AUTHOR]

Biogas slurry treatment has transformed from 'pollutant removal' to 'nutrient recovery' in the context of 'sustainable development' and 'circular economy'. The ammonia stripping process can be expected to efficiently remove the ammonia nitrogen for the nitrogen transformation and the nutrient recovery from the biogas slurry. The cost of alkali addition (especially sodium hydroxide (NaOH) and heating) can account for more than 70% of the total cost in the stripping process, leading to higher operation costs. Therefore, this study aims to reduce the energy consumption in the ammonia stripping of swine manure biogas slurry. The calcium oxide (CaO) was used instead of NaOH to adjust the pH value of biogas slurry, due to its lower price. Solar heating was used to treat the biogas slurry, instead of the traditional heating coupled ammonia stripping. The results showed that the CaO adjusted the pH value of biogas slurry, indicating a certain flocculation effect. A better performance was then obtained in the form of calcium hydroxide. Once the added concentration was 5 g/L, the pH value of the biogas slurry exceeded 12.0, where the removal rates of turbidity, COD, and TP reached 88.0%, 50.1 %, and 93.6 %, respectively. The influencing factors were ranked in the descending order of pH, temperature, and gas-liquid ratio on the efficiency of ammonia stripping. In the swine biogas slurry with the low buffering capacity, the pH of the swine biogas slurry should be controlled above 10.8 for the stripping, in order to ensure ≥70% ammonia nitrogen removal rate. Meanwhile, there was an increase in the temperature for the higher efficiency of ammonia stripping at the higher pH of the biogas slurry. Only when the pH and temperature of the biogas slurry were adjusted to the optimal ranges, the increasing gas-liquid ratio significantly promoted the ammonia stripping efficiency. The lowest running cost was achieved in the ammonia stripping process under the condition of a high pH value of 12.0 without heating (25 ℃) was about 2.46 CNY/m³. Compared with the temperature-driven ammonia removal rate, the cost was reduced by 52.1-68.7% among various stripping parameters (ammonia nitrogen removal rate > 80%). However, the heating further improved the ammonia nitrogen removal rate. The coupling of solar energy and ammonia stripping significantly increased the ammonia nitrogen removal rate. The biogas slurry was adjusted by CaO in the form of 10% calcium hydroxide with an additive concentration of 5 g/L. After that, the biogas slurry and air temperature increased to 40.7- 48.2 ℃ and 43.6-61.5 ℃ using solar collectors, respectively. The ammonia nitrogen removal rate of ≥ 97.5% was obtained by the self-developed solar-assisted heating ammonia stripping device in summer. Even in winter, the average air and biogas slurry temperatures after heating reached 37.6 and 31.4 ℃, respectively. The removal rate of ammonia nitrogen reached more than 86 %. This finding can provide a promising coupled solar application for the removal of low-cost ammonia nitrogen. [ABSTRACT FROM AUTHOR]

Anaerobic digestion (AD) is an alternative way to treat manure while producing biogas as a renewable fuel. To increase the efficiency of AD performance, accurate prediction of biogas yield in different working conditions is necessary. In this study, regression models were developed to estimate biogas production from co-digesting swine manure (SM) and waste kitchen oil (WKO) at mesophilic temperatures. A dataset was collected from the semi-continuous AD studies across nine treatments of SM and WKO, evaluated at 30, 35 and 40 °C. Application of polynomial regression models and variable interactions with the selected data resulted in an adjusted R2 value of 0.9656, much higher than the simple linear regression model (R2 = 0.7167). The significance of the model was observed with the mean absolute percentage error score of 4.16%. Biogas estimation using the final model resulted in a difference between predicted and actual values from 0.2 to 6.7%, except for one treatment which was 9.8% different than observed. A spreadsheet was created to estimate biogas production and other operational factors using substrate loading rates and temperature settings. This user-friendly program could be used as a decision-support tool to provide recommendations for some working conditions and estimation of the biogas yield under different scenarios. [ABSTRACT FROM AUTHOR]

The development of biofuels to replace fossil fuels with bioenergy systems has attracted attention as an environmental-friendly process. Dealing with biowaste by anaerobic digestion disposes of wastes and produces biogas during the treatment processes for providing the renewable energy source at a low cost while conserving fossil fuel. This study uses life cycle assessment and cost-benefit analysis to evaluate and compare environmental impacts and cost benefits before and after installing a rapid-build anaerobic fermentor module into the three-stage wastewater treatment system that the swine farm initially used. The module helps biogas production as energy recovery in swine farms. The results indicate that the module could help reduce carbon footprint by 22.6%, methane by 51.8%, sulfur oxides by 92.6%, nitrogen oxides by 74.2%, carbon monoxide by 54.7%, nitrous oxide by 28.6%, suspended particulate by 95.4%, and non-methane volatile organic compounds by 80%. Using this module made the reductions of damage impacts were human health 82%, ecosystem quality 59%, and resource scarcity 87%. The daily average biogas production was 46.38 m3, and its annual electricity generation income was 6091 USD. This study allows identifying the lowest environmental impact to support the adoption of sustainable waste treatment and the opportunity for converting waste to be energy and utilization with economic benefits for small-scale swine farms. [ABSTRACT FROM AUTHOR]

As environmental concerns and regulatory requirements increase over time, new alternatives for swine manure disposal emerge. Among them, anaerobic biodigestion is a relevant technology because it reduces the organic load of wastewater before its final disposal and provides economic benefits to farmers with biogas and biofertilizer production. Efficiently managing the anaerobic biodigestion process remains a challenge in developing countries, mainly due to the lack of information from swine meat producers to deal with the complexity of this system. A risk analysis can represent a promising tool for farm assistance because it provides a process overview. Hence, this study reports the results of a process mapping in a swine meat production farm in Minas Gerais, Brazil. This mapping was performed while monitoring biodigestion operational parameters and allowed the identification of the primary causes of process failures and potential environmental impacts. The results showed that anaerobic digestion promotes a relevant environmental gain. However, the need for improved process monitoring, investments in environmental assessment equipment, and technical training for producers also stood out as an improvement opportunity. [ABSTRACT FROM AUTHOR]

• Co-digesting swine manure and waste kitchen oil allowed OLR up to 6 g VS/L/d. • A reasonable amount of oil increased biogas yield and bacterial alpha-diversity. • System imbalance occurred when oil was added beyond certain threshold. • "Inhibited steady state" phenomenon was observed at high OLRs. • Up to three months were needed to confirm system failure for middle to high OLRs. Anaerobic co-digestion of swine manure (SM) and waste kitchen oil (WKO) was conducted to evaluate the effect of high organic loading rates (OLRs) on biogas production efficiency and microbial changes. Combinations of different loading rates of SM and WKO, with total OLRs from 2 to 8 g VS (volatile solid)/L/d, were evaluated in a laboratory-scale study. While feeding more than 4 g VS SM /L/d did not result in higher biogas production in both mono- and co-digestion scenarios, the addition of WKO increased the total OLR up to 6 g VS/L/d without significant reduction of system productivity. Biogas yields of M2O1 (2 g VS SM /L/d + 1 g VS WKO /L/d) and M4O2 were 910 ± 35 and 849 ± 85 mL/g VS fed which were 25.2 % and 16.9 % higher than the mono-digestion of M2, respectively. A significant increase of bacterial alpha-diversity (Shannon index) was observed in M2O1, at 233.0 ± 3.6 compared with 218.7 ± 5.1 of M2 (p < 0.05). Less bacterial alpha-diversity and accumulation of volatile fatty acids were observed in M4O1 and M4O2, suggesting their potential instability. When digesters were fed with M2, the introduction of 1.4 g VS WKO /L/d or more did not increase biogas yield and could cause system imbalance. The study suggests the limit of WKO could be increased when higher OLRs of SM were applied but should not be more than 4 g VS SM /L/d, and ratio between SM and WKO should be considered to avoid failure. Some of the system disturbances took up to three months to show. [ABSTRACT FROM AUTHOR]

The anaerobic digestion of swine manure was performed for more than 2 years in a biogas pilot plant with cereal residues as a mono-input, either by a simple intermittent substrate feeding or by feeding with an automated "autopilot" system under the direction of a Fuzzy logic control (FLC) system, working with a closed-loop feedback control. The pilot plant of the University of Applied Sciences in Nordhausen consisted of a 2.5 m3 dosage tank, a 2.5 m3 digestate tank, and a 1 m3 biogas reactor. Only three control parameters were used for FLC: pH, methane %, and the specific gas production rate (GPR) related to the organic loading rate (OLR), that is GPR/OLR m3 biogas/(kgVS d), vs = volatile solids. The specific GPR was referred to the OLR of the last feeding every 8 h in terms of kgVS/(m3 d). In test period I without an FLC system, a safe process with just an OLR of 4 kgVS/(m3 d) was reached, followed by an overloading and reactor disturbance at ≤6.3 kgVS/(m3 d) as indicated by acidification with volatile fatty acids up to 25,000 mg/L. However, test period II (585 trial days) with an integrated FLC system allowed a safe OLR up to 11 kgVS/(m3 d). Apparently, the microbes themselves directed the speed of substrate feeding by the dynamics of their substrate turnover and by the closed loop feedback control, while the three FLC parameters prevented acidification. Therefore, the application of FLC enabled a doubling of the throughput for a biogas reactor in the same time with a 'turbo speed'. The concomitant hydraulic residence time (HRT) of only 10 days reduced the stirring and heating costs. The usage of an FLC system should open the door for networked biogas production to enable flexible biogas production on demand. [ABSTRACT FROM AUTHOR]

Obtaining biogas from biomass, such as swine manure (SM), through anaerobic digestion (AD) is an alternative renewable energy source. In this context, this work aimed to analyze the influence of thermo-alkaline pretreatment (3 % NaOH at 121 °C for 30 min) and the substrate/inoculum ratio (SI) on AD at 10 and 15 % total solids – TS. Moreover, mathematical modeling and molecular biology tools were used to understand better the process and obtain kinetic parameters that assist in the optimization and scaling. The experiments were conducted in batch mode at 37 °C with orbital shaking at 150 rpm for 90 days. SM pretreatment increased cumulative methane yield from 30 to 205 mL/gVS. Furthermore, increasing the SI ratio from 1 to 3 gVS substrate /gVS inoculum enhanced this yield from 205 to 268 mL/gVS, although the lag phase increased from 0 to 3.5 days. When increasing the TS content to 15 %, the accumulated methane yield decreased to 136 mL/gVS, and the lag phase increased from 0 to 13 days. Regarding the microbiological evaluation, the genera Actinobacteriota and Chloroflexi were linked to higher methane production, and the dominant genus of archaea was Methanobacterium in almost all conditions tested. [Display omitted] [ABSTRACT FROM AUTHOR]

Although the promotive effect of direct interspecies electron transfer (DIET) on methane production has been well-documented, the practical applicability of DIET in different scenarios have not yet been systematically studied. This study compared the effects of magnetite-mediated DIET with conventional biogas mixing-driven interspecies hydrogen transfer (IHT) on anaerobic digestion (AD) of swine manure (SM). Compared with control, magnetite supplementation, biogas circulation, and their integration enhanced the CH 4 yield by 19.3%, 25.9%, and 26.2%, respectively. Magnetite mainly enriched DIET-related syntrophic bacteria (Anaerolineae and Synergistia) and methanogens (Methanosarcina) to accelerate acidification and establish DIET, while biogas circulation mainly enriched hydrolytic bacteria (Clostridia) and hydrogenotrophic methanogens (Methanolinea and Methanobacterium) to promote hydrolysis and accelerate IHT. Coupling magnetite addition with biogas circulation led to the enrichment of the above six microorganisms to different extents. The effectiveness of the strategies for lowering the H 2 pressure followed: magnetite + biogas circulation ≈ biogas circulation > magnetite. Under stress-free environment, the enhancement effect of magnetite-induced DIET was not even as pronounced as biogas circulation—a simple and common mixing strategy in commercial AD plants, and the promotion effect of magnetite was insignificant in the well-mixed digesters. In short, the magnetite-mediated DIET is not always effective in improving AD of SM. [Display omitted] • Effects of magnetite-mediated DIET and mixing-driven IHT on AD of SM were compared. • Magnetite mainly promoted acidification while biogas mixing enhanced hydrolysis. • Magnetite addition and biogas mixing increased the CH 4 yield by 19.3% and 25.9%. • Magnetite had little impact on CH 4 yield in biogas-circulated digesters. • Effect of biogas mixing on AD was slightly more pronounced than that of magnetite. [ABSTRACT FROM AUTHOR]

The co-digestion of swine manure with vegetable waste is an alternative that can increase the production of biogas and methane generated by the isolated digestion of manure. However, recommendations that are based on the best ratio between manure and forage, as well as the age of harvest, are still scarce in the literature. This study was conducted to evaluate inclusions (0, 25, 50, 75 and 100%) of the total solids (TS) of Elephant grass (Pennisetum purpureum Schum) harvested at two ages medium age (MA) at 45 days of growth and advanced age (AA) at 90 days in co-digestion with swine manure, using an entirely randomized design in a 5x2 factorial scheme. Batch digesters were used and biogas production was monitored for 12 weeks. There was influence of forage age (P <0.05) on the degradation of solids and neutral detergent fiber, with higher values for the substrates containing MA forage. The highest CH4 yields were obtained by the substrates containing MA forage in the inclusion of 27.7 and 31.6%, being 253.7 and 222.2 L of CH4 per Kg of total or volatile solids. The age of the forages influenced the onset and persistence of biogas production, being advantageous only in the inclusion of 25% of MA forage. The AA forage inclusion is not recommended for co-digestion with swine manure. [ABSTRACT FROM AUTHOR]

Introduction: The anaerobic digestion is an attractive process for a grains agro-industrial enterprise where several residues are produced. Different studies show the advantages of rice straw and rice dried residue with pig manure codigestion, however the effect of the mixture rice dried residue with pig and cow manure on anaerobic digestion kinetic have not been studied. Objective: To evaluate the methane production kinetic from different mixtures of rice dried residue with cow and pig manure in discontinuous system. Materials and Methods: The anaerobic digestion process was evaluated in discontinuous system at mesophilic conditions (35 ± 2 °C) for four mixtures, selected according to a Mixture design of extreme vertices. Four models of first and second order were used for the kinetic performance of the anaerobic digestion process description. Results and Discussion: The models explained between 98.54 until 99.90% the variability of obtained experimentally methane yield. The best methane yield (351.19 L/kg volatile solids) was obtained for the mixture with maximum percentage of rice dried residue. Conclusions: This study shows the potentialities of biogas production from residues generated in a grains agro-industrial enterprise. However, technology selection must be based in reactors with agitation, which must be evaluated in semicontinuous regime. [ABSTRACT FROM AUTHOR]

The methane production rate of high solid anaerobic digestion (HSAD) was poor although it was a promising technology with the advantages of small reactor, low energy consumption, and less digestate. In our research before, thermal treatment was proved to enhance HSAD's methane production rate via both batch experiments and continuous experiments of swine manure. However, the effect or investigation of thermal treatment's temperature-time combinations was not yet reported. In this study, swine manure was firstly thermally treated in 500-mL glass bottles with 400-mL work volume at 45–65 °C for 1–4 days. HSAD experiment of 10% solid content was then set up. The VS ratio of substrate to inoculum was 1:1. Thermal treatment at 45 °C (3 days), 55 °C (1 day), and 65 °C (3 days) could obtain the highest methane production rate, which was around 40% higher. Kinetics analysis suggested that the degradation of swine manure was quite different at different temperatures. Furthermore, energy assessment indicated that "thermal treatment + HSAD" had significant advantages in improving HSAD economic feasibility, because the improved methane production rate could compensate for the extra energy utilized for thermal treatment. Heat treatment at 45 °C (4 days) was preferred when the heating equipment was limited. Heat treatment at 55 °C (1 day) was preferred when the floor space and reactor volume were restricted. Heat treatment at 65°C (3 days) was preferred when the requirement of the digestate's sanitary condition is strict. [ABSTRACT FROM AUTHOR]

The objective of this study is to estimate the feasibility of payment for swine manure to small producers. For this, an economic feasibility analysis was carried out for the implementation of a biogas power plant considering three investment scenarios with different power generation capacities. Scenario 1 (C1) uses the 120 kVA motor generator (GMG) group. Scenario 2 (C2) uses the 330 kVA motor generator (GMG) group, and Scenario 3 (C3) uses the 420 kVA motor generator group (GMG). The biodigester analyzed is a model of covered pond (Canadian), with a depth of 4.5 meters, with HDPE geomembrane and a volume of 2,500m³. In the study, three tools were used to analyze the economic viability of the scenarios, the NPV (Net Present Value), the IRR (Internal Rate of Return), and the PAYBACK (Investment Recovery Time). It was concluded that the order of profitability is the scenarios: C3, C2, and C1, respectively. It was also concluded that the payment for swine manure is possible, allows the generation of extra income for the rural producer and obtains an attractive economic viability with the projects. [ABSTRACT FROM AUTHOR]

This study aimed to investigate effects of continuous low-speed biogas agitation on the anaerobic digestion (AD) performance and microbial community of high-solids pig manure (total solids content of 10%). Our results reveal that at a biogas agitation intensity of 1.10 L/g feed VS /d, CH 4 production increased by 16.67% compared to the non-agitated condition, the removal efficiency of H 2 S reached 63.18%, and the abundance of Methanosarcina was the highest. The presence of Hungateiclostridiaceae was associated with H 2 S concentrations. An increasing biogas agitation intensity led to an elevated pH and a decreased oxidation-reduction potential (ORP). Acetate concentrations, pH, and ORP values indicated changes in H 2 S concentrations. Sedimentibacter demonstrates the potential to indicate biogas agitation intensity and pH. We demonstrate that continuous low-speed biogas agitation effectively increases CH 4 production and reduces H 2 S concentrations in AD of high-solids pig manure, offering a potential technical pathway for developing AD processes for high-solids pig manure, it also demonstrates that AD process can reduce the risk of pathogen and parasite transmission. [Display omitted] • AD of high solids swine manure under low speed continuous biogas agitation. • Agitation resulted in an optimal increase in CH 4 production of 16.67%. • Agitation resulted in an optimal decrease H 2 S concentration of 70.72%. • Agitation resulted in an increase in pH and a decrease in ORP. • Sedimentibacter characterises the intensity of biogas agitation. [ABSTRACT FROM AUTHOR]

World's energy consumption has doubled in the last four decades, this demand has been covered by the usage of fossil fuels; which are an important source of greenhouse gases emissions, entailing climate change. An efficient less polluting management alternative is the anaerobic digestion (AD) process which generates biogas derived from organic matter. The methane contained at the biogas is considered a biofuel that can generate electricity and heat through its combustion. Biochemical Methane Potential (BMP) essays are standardized methodologies carried out to estimate the energy potential of an organic residue. After performing a BMP test for 13 residual biomass samples, it can be concluded that fresh livestock rumen and manure were the best substrates to generate higher biogas yields; ranging from 1119–1669 ml/g VSadded, with high methane content (65%4<77%) doubling the results reported at literature (≈550 ml biogas/g VSadded). Results indicate that energy potential of these residual biomasses can be increased 23–25% by improving management (freshness) and environmental (higher temperature) conditions and, by reducing the nutrimental deficiencies (mineral medium) of microorganisms. Fresh swine manure also produced large volumes of biogas (1150 ml biogas/g VSadded); however, average methane content ranged 50–65% CH4 v/v. The rest of the residual biomasses produced biogas and methane yields within the normal ranges (≈550 ml biogas/g VSadded); meaning that also can be used as substrate for bioenergy generation. Residues from aquaculture and fish based-industry produced low quantities of biogas (<250 ml biogas/g VSadded; CH4 < 20%); therefore, these cannot be recommended as substrates for bioenergy purposes. [ABSTRACT FROM AUTHOR]

Animal biomass is an important substrate in the anaerobic digestion process. The implementation of a waste technology for energy production, such as the production of biogas from animal waste, has been recognized in many countries as one of the best ways to achieve the Sustainable Energy Development Goals. Without a systematic review of resources and accurate estimation of available sources in terms of the amount of potential electricity, it is impossible to manage biomass rationally. The main aim of the article was to present a new tool for assessing the biomass of animal origin and estimating its potential energy through a computer database, which will be widely available in the end of 2020 to show results from the calculation using the database. This tool is configured to enter the data on the developed and undeveloped biomass resources in production of farm animals in rural areas in Poland. Calculations from the database show the biogas potential of swine and cattle manure and slurry in Poland, which is approximately 5.04 billion m3, with a 60% share of methane in biogas. It is the value of approximately 3.03 billion m3 of methane. It is worth underlining that slurry and manure are not high-energy substrates; therefore, it is necessary to introduce more energetic substrate streams to improve the biogas plant efficiency. [ABSTRACT FROM AUTHOR]

Antibiotic-resistant microorganisms are drawing a lot of attention due to their severe and irreversible consequences on human health. The animal industry is considered responsible in part because of the enormous volume of antibiotics used annually. In the current research, veterinary antibiotic (VA) degradation, finding the threshold of removal and recognizing the joint effects of chlortetracycline (CTC) and Tylosin combination on the digestion process were studied. Laboratory scale anaerobic digesters were utilized to investigate potential mitigation of VA in swine manure. The digesters had a working volume of 1.38 L (in 1.89-L glass jar), with a hydraulic retention time (HRT) of 21 days and a loading rate of 1.0 g-VS L−1 d −1 . Digesters were kept at 39 ± 2 ◦C in incubators and loaded every two days, produced biogas every 4 days and digester pH were measured weekly. The anaerobic digestion (AD) process was allowed 1.5 to 2 HRT to stabilize before adding the VAs. Tests were conducted to compare the effects of VAs onto manure nutrients, volatile solid removal, VA degradation, and biogas production. Concentrations of VA added to the manure samples were 263 to 298 mg/L of CTC, and 88 to 263 mg/L of Tylosin, respectively. Analysis of VA concentrations before and after the AD process was conducted to determine the VA degradation. Additional tests were also conducted to confirm the degradation of both VAs dissolved in water under room temperature and digester temperature. Some fluctuations of biogas production and operating variables were observed because of the VA addition. All CTC was found degraded even only after 6 days of storage in water solution; thus, there was no baseline to estimate the effects of AD. As for Tylosin, 100% degradation was observed due to the AD (removal was 100%, compared with 24–40% degradation observed in the 12-day water solution storage). Besides, complete Tylosin degradation was also observed in the digestate samples treated with a mixture of the two VAs. Lastly, amplicon sequencing was performed on each group by using the 50 most variable operational taxonomic units (OTUs)s and perfect discriminations were detected between groups. The effect of administration period and dosage of VAs on Phyla Firmicutes Proteobacteria, Synergistetes and Phylum Bacteroides was investigated. These biomarkers’ abundance can be employed to predict the sample’s treatment group. [ABSTRACT FROM AUTHOR]

Renewable energy can boost the growing population's need and rapid budgetary development. To reduce fossil fuel consumption is the initial purpose of renewable and sustainable energy, producing valuable bio-based products. The fermenters, using for pretreatment of swine manure, and involvement of swine carcasses are reported to enhance organic loading rate followed by improved biogas yield on household digesters. The compositions such as animal residues, pathogenic microbes, pharmaceutical residues and nutrient compositions including undigested feed are still confused. Therefore, it is mandatory to optimize and stabilize anaerobic practice and digestate filtration purification for consequential fertilizer consumption. The effective bio-methane recovery from energy-rich compounds is challenging due to slow degradation procedures. The pretreatment procedure could enhance lipid depolymerization and improve anaerobic fermentation. This article deeply focuses on biodegradation of swine manure. The components of this manure were evaluated and established several approaches to improve biogas production. Furthermore, recycling of co-digestates was discussed in detail as fertilizer consumption including hygienic aspects of manure and pretreatment strategies of biomass residues. Key points: • Co-digestion of manure and carcasses enhance bio-methane production. • Removel of ammonia from biogas digester may improve bio-methane gas. • A strong antimicrobial influence has been reported on biogas production. [ABSTRACT FROM AUTHOR]

In regions with developed animal husbandry, there is a problem of utilization of animal waste, which could be used as raw material for biogas production. In Russia most of the stations are designed and built by foreign companies taking into account generalized data on the properties of substrate. The particular characteristics of the local raw materials and substrates are not considered in the design process. Subsequently, this factor negatively affects the efficiency of biogas plants. In order to solve the problem, it is necessary to study the biogas potential of local substrates. The novelty of this work is to identify the peculiarities of pig manure as a substrate for biogas production depending on the classes of animals and the place of origin of raw materials. The goal of the present study of biogas potential of swine manure of different classes of animals (pregnant sows, lactating sows, piglets, fattening pigs) in Belgorod region of Russia. The experiment was carried out in small-scale batch reactors with the volume of 0.3 L each. Specific biogas yield from pig manure of different classes of animals ranged from 76.73 ± 11.77 to 151.42 ± 20.18 mn 3/t оDM, methane content – from 29.79 to 66.88%. In general, pig manure showed low biogas productivity. The highest rates were achieved at manure of sows. Taking into account the developed industry of pig breeding, biogas technologies, however, are the most optimal option of liquid manure utilization for the Belgorod region of Russia and are promising for many regions of the world with intensive animal breeding. When designing biogas plants, the specifics of local substrates should be taken into account. [ABSTRACT FROM AUTHOR]

As the demand for utilizing environment-friendly and sustainable energy sources is increasing, the adoption of waste-to-energy technologies has started gaining attention. Producing biogas via anaerobic digestion (AD) is promising andwell-established; however, this process inmany circumstances is unable to be cost competitive with natural gas. In this research, we provide a technical assessment of current process challenges and compare the cost of biogas production via the AD process from the literature, Aspen Plus process modeling, and CapdetWorks software. We also provide insights on critical factors affecting the AD process and recommendations on optimizing the process. We utilize four types of wet wastes, including wastewater sludge, food waste, swine manure, and fat, oil, and grease, to provide a quantitative assessment of theoretical energy yields of biogas production and its economic potential at different plant scales. Our results show that the cost of biogas production from process and economic models are in line with the literature with a potential to go even lower for small-scale plants with technological advancements. This research illuminates potential cost savings for biogas production using different wastes and guide investors to make informed decisions, while achieving waste management goals. [ABSTRACT FROM AUTHOR]

Due to the benefits of mitigating greenhouse gas emission and upgrading farmland fertilization, the valorization of liquor and biogas digestate from the anaerobic digestion of swine manure has attracted much attention in recent years. This article is based on the updated data/information from the official websites for summarizing the status of the swine-raising industry and innovative manure management, relevant sustainable development indicators, and inter-ministry promotion regulations in Taiwan. The survey findings revealed that the carbon dioxide emission reduction in 2019 was equivalent to about 36,000 metric tons based on a total of 2.35 million metric tons liquor and biogas digestate applied and 2 million swine heads for the biogas-to-power. Obviously, the regulatory measures by the Council of Agriculture, the Environmental Protection Administration, and the Ministry of Economic Affairs have provided economic and financial supports towards the reduction of 67.39 x 10³ metric tons carbon dioxide equivalent by 2030. Using the principles of biorefinery and zero-waste, the integration of anaerobic digestion, by-products (liquor and digestate), and biogas-to-power for treating swine manure is a win-win-win option for environmental, energy, and economic benefits. [ABSTRACT FROM AUTHOR]

An anaerobic sequencing batch reactor (ASBR) is a high-rate anaerobic digestion system ideally suited for the treatment of liquids with high organic strength and low solids content. Biota are retained in an ASBR by settling solids prior to decanting effluent from the top of the reactor. Solids retention time (SRT) can be managed separately from hydraulic retention time (HRT) in an ASBR. One problem encountered with ASBRs is poor solids retention due to inefficient solids settling. A novel mixing system in which solids are only partially mixed in the reactor prior to decanting was investigated in a series of three experiments. A battery of six 30 L ASBR reactors were fed a mixture of dilute swine manure (0.30% TS, 0.20% VS) and raw glycerol. In a side-by-side comparison of two reactors operated at an organic loading rate (OLR) of 0.30 g COD L-1 d-1 with 15-day HRT and two feeding cycles per day, the partially mixed reactor outperformed the fully mixed reactor as measured by effluent quality (130 vs. 350 mg VSS L-1), SRT (354 vs. 52 days), and VS removal efficiency (88% vs. 79%). In a replicated study of five reactors operated at 0.31 g COD L-1 d-1 OLR, 15-day HRT, and two feeding cycles per day before and after switching from full to partial mixing, the partially mixed reactors showed significantly (p = 0.05) better performance as measured by effluent quality (100 vs. 382 mg VSS L-1), SRT (760 vs. 72 days), and VS removal efficiency (85% vs. 71%). Biogas production did not significantly change with the change from full to partial mixing in the five replicated reactors, i.e., average biogas yield was 0.81 and 0.77 L biogas g-1 COD with partial and full mixing, respectively. Effluent quality, SRT, VS removal efficiency, and biogas yield did not significantly change when the OLR was increased from 0.31 to 0.62 g COD L-1 d-1 and HRT was reduced from 15 to 7.5 days in a replicated study of six partially mixed reactors. A mass balance of COD across the six partially mixed reactors showed that endogenous respiration of retained biomass accounted for approximately 50% of the biogas produced by an ASBR with SRT exceeding 400 days. [ABSTRACT FROM AUTHOR]

The Brazilian pig production brings positive returns to agribusiness, even with the environmentally harmful factors that occurs due to the polluting potential of this activity, owing to inadequate handling of swine manure. To reduce such impacts requires the use of efficient and sustainable waste treatment systems. The goal of this study was to analyze the economic viability for the implantation of a biodigester system for treating the waste from a 1.500 sow breeding plant, making it possible to produce biogas as an alternative source of clean electric energy. For this was used bibliographic research about the subject matter and development of real sceneries possible. Two investment sceneries were compared: I) 20% equity and 80% financed; and II) 100% equity. It was conclude that the investments are sustainable and economically viable too, in both situations, with the II being the most advantageous one, which presented lower risk based on calculated IRR, NPV and IL. [ABSTRACT FROM AUTHOR]

The optimization of anaerobic digestion systems for enhanced biogas production is reliant on the manipulation of feeding regimes and organic loading. However, the impact of these operations on the microbiota remains unclear. Here, the effects of three distinct feeding regimes (once daily, every 2nd day, and every 3rd day) with two different loading amounts (300 g and 500 g) were investigated in 2 continuously stirred tank reactors treating swine manure. Results indicated that the high organic loading (500 g daily feeding) resulted in increased biogas and methane production, albeit with reduced archaeal alpha diversity. Furthermore, a significant alteration in species distribution was observed with sudden feeding regime changes (300 g every 2nd day) and higher organic loading. Wherein, the core species determined the methane production regarding the different organic loading. The resultant species turnover likely drove the increased biogas production while species loss contributed to the fluctuation of biogas production in intermittent feeding regimes. Despite a decrease in positive connections with high organic loading, the connectivity of Methanosarcinaceae with bacteria increased, thus ensuring higher biogas production. In conclusion, the present study underscores the association between feeding strategies and elevated levels of organic loading with regards to the interdependence between methanogenic microorganisms and keystone bacterial populations. As a consequence, this interplay exerts a discernible influence on the biogas production process. • Continuous high load increased biogas by linking between methanogens and bacteria. • The flux biogas stimulated by the intermittent feed caused by low species turnover. • Microbial rare taxa responded operational changes sensitively. • Methanosarcina centered links guaranteed biogas production. [ABSTRACT FROM AUTHOR]

Under the African swine fever epidemic, the extensive use of lime disinfectants has seriously inhibited anaerobic digestion (AD). In this study, the subject was swine manure containing lime disinfectant wastewater. The research set up a carbon dioxide (CO 2) bubbling pretreatment device before it entered AD to explore the effect of breaking the inhibition of lime disinfectant. The results showed that the initial pulmonary hypertension (pH) of 11.0 and CO 2 bubbling time of 8 h had the best effect, which could reduce calcium ion (Ca2+) by 73.0%, and the biogas production of the batch AD test increased by 28 times. In the continuous AD test, the Ca2+ of CK increased to 7.67 g/L, while the S1 pretreated by CO 2 bubbling stabilized at 2.6 g/L, the biogas production in S1 was 112.4% higher than in CK. CO 2 bubbling pretreatment reduces the concentration of Ca2+ in swine by utilizing the combination of exogenous CO 2 and Ca2+, breaking the inhibitory effect on AD, and thereby improving the performance of the AD system. The test used CO 2 in biogas to break the inhibition of lime disinfectants on AD, which was a convenient and feasible pretreatment process. [Display omitted] • CO 2 bubble pretreatment can reduce fecal calcium ions by 73.0%. • After pretreatment, the biogas yield in the batch anaerobic digestion test increased by 28 times. • The biogas yield in the continuous anaerobic digestion test increased by 112.4% after pretreatment. [ABSTRACT FROM AUTHOR]

Microbial electrochemical technology (MET) that can harvest electricity/valuable materials and enhance the efficiency of conventional biological processes through the redox reaction of organic/inorganic compounds has attracted considerable attention. MET-based anaerobic digestion (AD) systems treating swine manure were operated at different applied voltages (0.1, 0.3, 0.5, 0.7, and 0.9 V) and temperatures (25, 35, and 45 °C). Among the MET-based AD systems with different applied voltages at 35 °C, M4 at 0.7 V showed the highest methane production (2.96 m3-CH4/m3) and methane yield (0.64 m3-CH4/kg-VS). The methane production and yield increased with increasing temperature at an applied voltage of 0.7 V. Nevertheless, the MET-based AD systems (LM at 25 °C and 0.7V) showed competitive AD performance (2.33 m3-CH4/m3 and 0.53 m3-CH4/VS) compared with the conventional AD system (35 °C). The microbial community was affected by the applied voltage and temperature, and hydrogenotrophic methanogens such as M. flavescens, M. hungatei, and M. thermautotrophicus were mainly responsible for methane production in MET-based AD systems. Therefore, the methane production can be enhanced by an applied voltage or by direct interspecies electron transfer because M. flavescens and M. thermautotrophicus were especially predominant in cathode of MET-based AD systems. The MET-based AD systems can help enhance biogas production from swine manure with no significant change in methane content. Furthermore, MET-based AD systems will be a promising AD system through low material development and the optimal operation. [ABSTRACT FROM AUTHOR]

Summary: Domestic heating systems have long been playing a significant role in China's energy structure. The sustainability of a hybrid solar‐biogas heating system (SBHS) under various feedstock fermentation scenarios was evaluated using emergy analysis. Representative emergy indices such as transformities, emergy yield ratio (EYR), environmental loading ratio (ELR), emergy sustainability index (ESI), ratio of waste treatment (%W), feedback yield ratio (FYR), and emission mitigation intensity (EMI; g/1010 sej) were selected to evaluate the sustainability performance of different feedstock scenarios including cow dung (CD), swine manure (SM), and poultry manure (PM). The results showed that PM fermentation scenario had greater market competitiveness, lower environmental pressure, better sustainability, and self‐organizing ability than the other two options. However, both the emergy efficiency and the CO2 emissions mitigation intensity of PM scenario were worse than that of the SM and CD. Moreover, compared with other biogas systems and traditional agricultural systems, the hybrid SBHS was proved to be a promising mode for the treatment of rural manure waste with favorable economic benefits and environmental sustainability. [ABSTRACT FROM AUTHOR]

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The aim of this study was to investigate how the microbial community structure adapts during the start-up phase and how the 13C fractionation of biogas reflects the microbial population dynamics in two parallel swine manure–fed anaerobic digesters. Two swine manure–fed reactors for the start-up of continuously stirred tank reactors at mesophilic condition were evaluated. Changes in community structure were monitored using 16S rRNA high-throughput sequencing to measure the abundance of fermenting bacteria and methanogens. Digesters with relatively stable Methanosarcinaceae started up successfully and contained high gas production and low levels of propionate. In contrast, the digester that experienced a difficult start-up period had reduced Methanosarcinaceae along with accumulated propionate and low gas production. Specific gas production, specific methane production, and 13C fractionation of biogas were influenced significantly by Methanosarcinaceae, Methanobacteriaceae, and Clostridiaceae, indicating that the 13C fractionation of biogas had significant potential to reflect microbial population changes and digester performance during the start-up period. [ABSTRACT FROM AUTHOR]

Highlights • Five feedstocks were used to evaluate isotope fractionation in biogas. • Characteristic δ 13C-biogas and community structure were detected in 5 feedstocks. • Cellulose and nitrogen rich feedstocks had more depleted δ 13CH 4 values. • Synergistaceae was found as core species in all reactors. Abstract Feedstock type influences bacterial and methanogenic communities in anaerobic digestion. These two communities work tightly to maintain the stability of anaerobic digestion. How to quick report the changes of microbial community structure especially methanogenesis is the key issue for optimizing anaerobic digestion process. In this study, 13C isotope fractionations of CH 4 and CO 2 in biogas and microbial community composition were analyzed in 5 different feedstocks. Our results showed that grass silage, maize silage and swine manure fed reactors had similar δ 13C values and methanogenic community composition, dominated by Methanosarcinaceae. The lowest δ 13CH 4 values were detected in straw and chicken manure fed reactors, reflecting reduced microbial degradation of material or the presence of toxic components in these feedstocks. The straw fed bioreactor lead to low δ 13CH 4 values, probably reflecting relatively high levels of the syntrophic acetate oxidizing bacteria, Synergistaceae and Syntrophaceae , which might work collectively with hydrogenotrophic methanogens, resulting in the low δ 13CH 4 values in this bioreactor. Significantly, all core microbes in the 5 different feedstock fed bioreactors were either Clostridia species or related to the Synergistaceae (syntrophic acetate oxidizing bacteria). [ABSTRACT FROM AUTHOR]

Long-term anaerobic co-digestion of swine manure (SM) and corn stover (CS) was conducted using semi-continuously loaded digesters under mesophilic conditions. A preliminary test was first conducted to test the effects of loading rates, and results indicated the 3 g-VS L−1 d−1 was the optimal loading rate. Based on the preliminary results, a verification replicated test was conducted with 3 g-VS L−1 d−1 loading rate and different SM/CS ratios (1:1, 2:1 and 1:2). Results showed that a SM/CS ratio of 2/1 was optimal, based on maximum observed methane-VSdes generation and carbon conversion efficiency (72.56 ± 3.40 mL g−1 and 40.59%, respectively). Amplicon sequencing analysis suggested that microbial diversity was increased with CS loading. Amino-acid-degrading bacteria were abundant in the treatment groups. Archaea Methanoculleus could enhance biogas and methane productions.

In the livestock enterprises, the wastes which are produced after the production can be shown as a pollutant source when not properly managed. Wastes from livestock enterprises must be stored and managed properly. The use of renewable energy sources is increasing due to the reduction of fossil energy resources and the environmental pollution of these resources. Biogas energy production among renewable energy sources in the direction of developing technology and increasing population needs can be applied in areas where animal breeding facilities are carried out. In case of animal wastes reaching underground and surface water resources for biogas production, water pollution will occur. Therefore, the properly storage of wastes on animal barns and transfer to biogas plants may remove the potential negative effects on water resources. In cases where waste from livestock enterprises is not stored properly, these enterprises will be the source of pollutants for water resources. In study area, primarily livestock potential enterprises that will cause pollution problems to water resources have been determined. Potential biogas quantities to be generated from these facilities have been calculated and the potential contributions of livestock enterprises to energy costs have been investigated. [ABSTRACT FROM AUTHOR]

Due to the extensive use of feed additives and drugs, heavy metal residues in pig manures of large-scale farms increased. In order to reduce the pollution of heavy metals in pig manures, the influence of the passivating agent on the content and morphological transformation of As in the fermentation process was clarified, so as to provide a scientific basis for the safe and rational utilization of the biogas residue. The study focused on the heavy metal As, pig manure fermentation raw materials, the anaerobic fermentation technology. The orthogonal tests with three factors and 3 levels of each factor were designed, using BCR extraction method to analyze the heavy metal morphology. Different types of passivating agents (fly ash, diatomaceous earth, activated carbon), addition ratios of passivating agents (2.5%, 5%, 7.5% in pig manures) and fermentation temperatures (25, 30, 35 ℃) were studied. The influence of heavy metal passivation results showed that: 1) After anaerobic fermentation of pig manures, most of the heavy metal As remained in the biogas residue, and the content range in the biogas residue was between 5.50-6.56 mg/kg. The effects of passivating agents and their adding ratio and fermentation temperature on the content of As in biogas residue were not significant. In the 9 groups of experimental treatment, under 2.5% fly ash and fermentation temperature of 25 ℃, the proportion of oxidizable state could be increased to the maximum, which accounted for 7.94%, and was 5.14% higher than that before fermentation. Under the conditions of activated carbon and fermentation temperature of 35 ℃, the residual state of As accounted for the most, which was 84.27%, and was 21.66% higher than that before fermentation. Therefore, addition of different kinds of passivating agents during anaerobic fermentation for pig manure could decrease the effectiveness of heavy metal As. 2) The order of influencing factors on the passivation effect of heavy metal As were follows: passivation agent, addition ratios of passivating agent and fermentation temperature. The passivation effect of passivating agent types on the effective state of heavy metal As in biogas residue was significant, and the passivation effects of passivation agent addition ratio and fermentation temperature were not significant. Therefore, adding passivation agent with optimal content during the anaerobic fermentation of pig manure could transform the effective state of As to a stable state. 3) The treatment with the best passivation effect of As was 7.5% activated carbon and the fermentation temperature of 30 ℃. According to the verification test, the passivation effect could reach 62.34%, which was not significant different with the best treatment (61.46%) in the 9th group of the orthogonal test. The addition of passivating agent during the anaerobic fermentation of pig manures can improve the passivation effect of heavy metal As in biogas residue, which can effectively promote the sustainable development of biogas project. [ABSTRACT FROM AUTHOR]

High levels of methane production from swine operations have been associated with foam accumulation in deep-pit manure storage systems. This foam poses both a safety concern (i.e., flash fires) and operational challenges in managing stored manure. Mitigating methane production is one approach to controlling foam accumulation. In this study, swine manures obtained from three deep-pit storage barns in central Iowa were dosed with narasin to evaluate its inhibitory effects on methane and biogas production. Dose rates ranged from 0 to 3.0 mg narasin kg-1 manure. Overall, methane rates were reduced by 9% for each mg of narasin added per kg of manure, and this reduction was effective for up to 25 days. However, the inhibitory effect weakened with time such that no statistical difference in cumulative methane production between samples dosed with narasin and undosed controls could be detected after 120 days of incubation. In addition to methane rates, narasin addition reduced the degradation of total and volatile solids in the manure by 1.9% and 2.6%, respectively, for each mg of narasin added per kg of manure. Additional study treatments included sugar (10 g kg-1 manure) with and without narasin (1.5 mg narasin kg-1 manure). Results from this treatment showed that methane production was initially increased by the sugar addition, but the effect lasted less than six days, at which point cumulative methane production was similar to the control. When treated with both narasin and sugar, the inhibitory effect did not impact gas production during the sugar digestion phase but did reduce methane and biogas production thereafter. The addition of sugar and the rate of narasin addition caused changes to the microbial community as compared to the control. Overall, the results indicated that narasin can be an effective additive for reducing methane emission from swine manure, but further study is needed to recommend dosing frequency and to evaluate how continuous addition of manure impacts narasin effectiveness. [ABSTRACT FROM AUTHOR]

The containment in pig farming generates a large volume of effluent that can be treated by anaerobic digestion. To use the biogas generated in the process, in electricity generation, a better understanding of the variables involved is necessary. The objective of this study was the evaluation of biogas production parameters, power generation, performance of the generator group in the biogas conversion into electric energy and the avoided cost of electric energy of a pig farming property. Parameters of concentration, biogas production and consumption, and generation of electric energy were monitored, and the information generated was stored in a database. The results have indicated an average daily production of 443 m 3 , with an average of 0.10 m 3 of biogas per pig and an average concentration of 68% methane. The average of electric energy generation was 324.5 kWh/day, and the efficiency of the generator was 17% with an average active power of 70 kW and a daily operation of 6.5 h. The avoided cost by self-consumption of electric energy generated in the property was R$ 13718.20, and during the monitoring period there was a total generation of electric energy of 70.5 MWh, of which 26.6 MWh were exported to the distribution network. The study also emphasizes that the appropriate choice of sensors and the methodology for monitoring and collecting data continuously could lead to an important data to use in correlated studies concerning generation of electricity from biogas. [ABSTRACT FROM AUTHOR]

The effect of recycled utilization of liquid digestate on methane production and system stability of anaerobic digestion of pig manure were investigated. Two continuous stirred tank reactors were operated for 230 days with varying organic loading rates (OLRs, from 1.5 to 6 g VS L −1 d −1 ); one reactor was implemented with liquid digestate recirculation and the other was set as the control without recirculation. The present study contributed to prove that digestates recirculation operation could improve the bioenergy production in the anaerobic digestion of pig manure under the OLRs below 5 g VS L −1 d −1 . The inhibition of methane production was found under an OLR of 6 VS L −1 d −1 , which was caused by significantly increased viscosity from 30 to 1000 mPa s and decreased mass transfer characteristics. The previously reported negative effects of accumulated ammonia and VFA on anaerobic digestion under digestate recirculation were not found. However, the heavy metals Pb, Mn, Cu and Zn accumulated in both liquid and solid fractions of the generated digestate in the digestate recycled reactor. Moreover, the stable carbon isotope analysis of δ 13 C CO2 and δ 13 C CH4 in produced the biogas indicate different methanogenic pathways between the anaerobic reactors with and without digestate recirculation. [ABSTRACT FROM AUTHOR]

In this study, was studied the biogas generation from swine manure, using residual glycerine supplementation. The biogas production by digestion occurred in the anaerobic batch system under mesophilic conditions (35°C), with a hydraulic retention time of 48 days. The experiment was performed with 48 samples divided into four groups, from these, one was kept as a control (without glycerin) and the other three groups were respectively supplemented with residual glycerine in the percentage of 3%, 6% and 9% of the total volume of the samples. The volume of biogas was controlled by an automated system for reading in laboratory scale and the quality of the biogas (CH4) measured from a specific sensor. The results showed that the residual glycerine has high potential for biogas production, with increases of 124.95%, 156.98% and 197.83% in the groups 3%, 6% and 9%, respectively, relative to the sample control. However, very high organic loads can compromise the process of digestion affecting the quality of the biogas generated in relation to methane.

This Article deals with the utilization of agricultural waste such as cattle manure, swine manure, chicken manure and their mixtures. It is promising a simultaneous running of biogas processes and vermitechnology. A special biogas-vermitechnological shoulder was constructed. A special organic catalyst, which contained glucose and cellulose, was used in the biogas process, as a source of biogas bacteria and to alter C/ N ratio of the fermented substrate, to C/ N = 30/1. Swine manure shows a higher biogas yield and methane-in-biogas content than others. It is effective to mix different manures to increase biogas yield. Earthworms Eisenia Foetida were used in the vermitechnological stage. Using only cattle manure and in mixtures with leaves (4:1 wt) was processed to make vermicompost. The obtained biohumus was studied with a microscope. It was found to have a more homogenous and structured porosity surface. It was observed that the organic content increased in vermicompost. The ratio of humic and fulvic acids can be varied using rotted leaves as fillers. Atomic Absorption Spectrometry was used to determine the content of metals. It was observed that metals from manure (Sb, Rb, Sr) were accumulated in earthworms, therefore biohumus was purified from pollutants. The released heat from the biogas stage was used for the vermitechnology stage heating. Using the biogas heat, it is possible to conduct the vermiprocess, even in cold seasons. [ABSTRACT FROM AUTHOR]

Manure represents an exquisite mining opportunity for nutrient recovery (nitrogen and phosphorus), and for their reuse as renewable fertilisers. The ManureEcoMine proposes an integrated approach of technologies, operated in a pilot-scale installation treating swine manure (83.7%) and Ecofrit® (16.3%), a mix of vegetable residues. Thermophilic anaerobic digestion was performed for 150 days, the final organic loading rate was 4.6 kgCOD m-3 d-1, with a biogas production rate of 1.4 Nm3 m-3 d-1. The digester was coupled to an ammonia side-stream stripping column and a scrubbing unit for free ammonia inhibition reduction in the digester, and nitrogen recovery as ammonium sulphate. The stripped digestate was recirculated daily in the digester for 15 days (68% of the digester volume), increasing the gas production rate by 27%. Following a decanter centrifuge, the digestate liquid fraction was treated with an ultrafiltration membrane. The filtrate was fed into a struvite reactor, with a phosphorus recovery efficiency of 83% (as orthophosphate). Acidification of digestate could increment the soluble orthophosphate concentration up to four times, enhancing phosphorus enrichment in the liquid fraction and its recovery via struvite. A synergistic combination of manure processing steps was demonstrated to be technologically feasible to upgrade livestock waste into refined, concentrated fertilisers. [ABSTRACT FROM AUTHOR]

The presence of elevated concentrations of hydrogen sulphide (H2S) in piggery biogas is problematic due to its corrosiveness and toxicity. At small scale, the cost of using iron or carbon-based commercial filter media to remove H2S can act as a barrier to the uptake of on-farm biogas technology. To identify cost-effective, alternative options, this study tested and compared H2S removal by the commercial iron-oxide H2S scavenger (cg5) with the alternative solid media: granulated steel furnace slag (GSFS), red soil, compost, composted beef feedlot manure, granular activated carbon (GAC) and biochar. Experiments measured single-pass H2S removal from a pre-humidified standard gas (2000 ppm H2S in nitrogen) onto solid media contained in a cylindrical plastic column (DN 25 mm, depth 110-147 mm). The commercial medium (cg5) performed considerably better than the other media, achieving sulphur removal of 143 g S/kg medium at breakthrough (>10 ppm outlet H2S). A red soil was the most promising alternative medium (2-12 g S/kg medium at breakthrough). The crystalline structure of the iron-oxide minerals appeared to strongly influence the H2S removal capacity of the red soils, and pressure drop was generally high. Bulking with ground sugar cane mulch (SCM) was effective at reducing pressure drop. Interestingly, H2S removal with red soil improved when the soil was regenerated by exposure to air, followed by reuse in the column. Overall, red soil may be a suitable low-cost option, especially for polishing biogas after initial biological H2S removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrification-denitrification existed in AD systems and contributed to TAN removal. • Biogas circulation and AC addition lowered the TAN by 6% and 2%, respectively. • Both strategies enriched nitrification-/denitrification-related bacteria or genes. • Their combination had a synergetic effect on enrichment of specific bacteria/genes. • Combined strategy led to a 24% lower TAN level and a 44% higher CH 4 yield. This study investigated the biological nitrogen removal mechanisms during the anaerobic digestion of swine manure and the effects of biogas circulation and activated carbon (AC) addition. Biogas circulation, AC addition, and their combination increased the methane yield by 25.9%, 22.3%, and 44.1%, respectively, when compared to the control. Nitrogen species analysis and metagenomic results indicated that nitrification–denitrification was the dominant ammonia removal pathway in all digesters with little oxygen, while anammox did not occur. Biogas circulation could promote mass transfer and induce air infiltration to enrich nitrification- and denitrification-related bacteria and functional genes. And AC might act as an electron shuttle to facilitate ammonia removal. The combined strategies showed a synergetic effect on the enrichment of nitrification and denitrification bacteria and functional genes, significantly lowering the total ammonia nitrogen by 23.6%. A single digester with biogas circulation and AC addition could enhance methanogenesis and ammonia removal via nitrification and denitrification. [ABSTRACT FROM AUTHOR]

[Display omitted] • Steady-state, acclimated microalgae can upgrade biogas with up to 4000 ppm H 2 S. • Steady-state, acclimated microalgae can grow in digestate with 1.6 g/L NH 4 -N. • CO 2 and H 2 S removal was achieved in a wide range of biogas: digestate ratios. • CO 2 was fixed as biomass and some soluble organics. • Most NH 4 -N was converted to Org-N and PO 4 -P to Org-P or Poly-P. Microalgae have the potential for biogas upgrading and digestate management as a downstream technology of anaerobic digestion. Through the acclimation to typical swine manure digestate with 1630 mg/L NH 4 -N, semi-continuous microalgae treatment was operated for biogas treatment with up to 4000 ppm H 2 S. Control of pH was necessary at high biogas to digestate liquid (G/L) ratios above 1 mol/L or 25:1 v / v (1 atm, 25 °C). Biogas decarbonation and desulfurization were achieved simultaneously with G/L ratios from 0.04 to 1.63 mol/L (1:1 to 40:1 v / v , at 1 atm, 25 °C), and nearly all methane remained in the upgraded biogas. Ammonia nitrogen as high as 930 mg NH 4 -N/L/d was removed at higher G/L ratios. The removed carbon and nitrogen were captured and assimilated into biomass at rates up to 13 g CO 2 /L/d and 540 mg NH 4 -N/L/d, respectively. The optimal phosphorus assimilation rate was 49 mg PO 4 -P/L/d obtained at the G/L ratio of 1.02 mol/L. These findings demonstrate that microalgal can treat high-H 2 S biogas and high-NH 4 -N digestate within a broad range of G/L ratios, including ratios that are similar to biogas and digestate generation ratios from swine manure digesters. [ABSTRACT FROM AUTHOR]

In this paper, biogas was produced by anaerobic digestion (AD) of swine manure. This study aimed to isolate, select and identify microorganisms able to increase waste conversion into biogas rich in methane. These microorganisms were isolated from sewage sludge after the beginning of the AD process. Inocula of isolated microorganisms were added to the samples of swine manure. The animals from which the manure was obtained were fed with oat (O) or with swine feed (F). Inoculum addition increased methane mole fraction for O-manure sample from 0.35 to 0.60 and for F-manure sample from 0.40 to 0.70 (average values). An experimental design (2k) was used to determine statistical significance of liquid medium addition and initial pH value. Both factors had a significant effect on the methane volume produced. In summary, microorganisms addition increased biogas volume and the methane mole fraction in it. [ABSTRACT FROM AUTHOR]

Intensive monitoring was carried out to evaluate the performance of a full-scale innovative swine waste-to-energy system at a commercial swine farm with 8640 heads of swine. Detailed mass balances over each unit of the system showed that the system, which includes a 7600 m 3 anaerobic digester, a 65-kW microturbine, and a 4200 m 3 aeration basin, was able to remove up to 92% of the chemical oxygen demand (COD), 99% of the biological oxygen demand (BOD), 77% of the total nitrogen (TN), and 82% of the total phosphorous (TP) discharged into the system as fresh pig waste. The overall biogas yield based on the COD input was 64% of the maximum theoretical, a value that indicates that even greater environmental benefits could be obtained with process optimization. Overall, the characterization of the materials fluxes in the system provides a greater understanding of the fate of organics and nutrients in large scale animal waste management systems. [ABSTRACT FROM AUTHOR]