Anaerobic Digestion For Biogas Production Research Articles

Impact of Design and Mixing Strategies on Biogas Production in Anaerobic Digesters

Anaerobic digestion (AD) is a biological process that breaks down organic matter in the absence of oxygen, producing biogas and nutrient-rich digestate. Various reactor designs and mixing strategies are well-established in AD processes, each with their own advantages and benefits. The presented study summarizes and investigates the state of the art of AD in domestic wastewater treatment plants (WWTPs) in an Austrian alpine region, with a primary focus on finding similarities among the most efficient plants regarding digester design, mixing approaches, and biogas production. By combining surveys and detailed field studies in cooperation with 34 WWTPs, the study provides a comprehensive overview of common AD practices, reactor shapes, and inherent mixing methods, highlighting their potential regarding energetic efficiency and biogas production. The results of the survey reveal qualitative trends in efficient AD design alongside detailed quantitative data derived from the supervised in-field optimization studies. Notably, one of the studies demonstrated energetic savings of 52% with no decrease in biogas production, achieved by transitioning from gas injection to mechanical agitation. Redundant impeller-based overmixing was also practically investigated and demonstrated in another field study. After optimization, the adaptations also resulted in energy savings of 30%, still proving sufficient substrate mixing with biomethane potential analysis. In conclusion, this research emphasizes the economic and environmental importance of energy-refined practices and optimized processes while highlighting the sustainability of AD, particularly for large domestic WWTPs but also for different comparable applications.

Novel insights from agricultural waste to acetic acid through regulated high-solids anaerobic digestion: Focus on the key microbial communities

Acetic acid (HAc) is an essential intermediate for improving the efficiency of biogas production in anaerobic digestion (AD) or for the production of liquid chemicals. The relationships between the mechanisms and microbial contributions of targeted regulation of HAc production in high-solids AD remains unclear. This study represents a breakthrough in revealing the mechanism of pH directed regulation of HAc production and microbial interactions. The regulation of the initial spray pH effectively improved the substrate hydrolysis rate and increased the concentration of HAc, with an average HAc percentage of total organic acids was 66.20 %. Microecological analysis revealed that rare species played a vital role in acidification, with all key acetogenic microbes identified as rare species. Additionally, the construction of a bacterial–environmental factor co-occurrence network revealed that lowering the initial spray pH enhanced the synergistic interactions among bacterial communities, and proportion of positive interactions among bacteria was 82.23 %. The gene abundance of key enzymes in the acetate-type metabolic pathway dominated in the acidogenesis phase. Furthermore, a regression model was established between the HAc indicator microbe (Acinetobacter) and HAc yields. Overall, the results of this study indicate that pH regulation plays an important role in strengthening the production of HAc and rare species significantly contributed to HAc production.

Study on biogas production from pig manure wastewater by microbial electrosynthesis at sub-psychrophilic conditions

In colder regions, relatively low temperatures results in low microbial activity and low biogas production in anaerobic digestion. This study investigated if microbial electrosynthesis system (MES) can enhance biogas production from pig manure wastewater under sub-psychrophilic conditions (20 °C). Results showed that the applied voltage of MES (0.4 V and 0.8 V) significantly increased the biogas production and COD removal rate. Biogas production and COD removal rate increased most when the voltage reached 0.8 V (34.77 %, 26.67 %), and decreased when the voltage was 1.2 V. Low voltage (≤ 0.8 V) did not significantly alter the microbial structure, but higher voltage (1.2 V) resulted in a significant decrease in Clostridium and Methanosarcina. Coenzyme F420, NADH, as indicators for methanogenic efficiency, showed the highest fluorescence intensity at 0.8 V and decreased at 1.2 V. Results indicated that the improvement of gas production was mainly due to the improvement of key enzymes rather than the shift of microbial structure. The information provided will be useful to improve the efficiency of biogas production.

Impacts of free nitrous acid on stabilizing food waste and sewage sludge for anaerobic digestion

This work investigated the effectiveness of free nitrous acid (FNA) in enhancing organic waste solubilization to improve biogas production in anaerobic digestion (AD). The results indicated that FNA pretreatment can enhance soluble organic content and control H2S odor in tested organic wastes, including food waste, sewage sludge, and their combination. However, a significant decrease (>50 %) in FNA concentration was found in the reactors, possibly due to denitrifier-driven NO2– consumption. Biochemical methane potential (BMP) tests showed a 25 ± 8 % enhancement in CH4 production in the reactors fed with mixed substrate pretreated with 2.9 mg FNA-N/L. However, the presence of NO2– (325.6–2368.0 mg N/L) in some BMP reactors, due to carryover from FNA pretreatment, adversely affected CH4 production (>55 %) and prolonged lag time (>4.2 times). These findings are valuable for researchers and practitioners in waste management, offering insights for implementing FNA pretreatment to enhance the biodegradability of organic wastes in AD.

Enhancing biogas production through photocatalytic pretreatment of rice straw co-digested with cow dung and food waste using a novel g-C3N4/SiO2/bentonite catalyst

This study investigates the application of a novel composite photocatalyst, g-C3N4/SiO2/ Bentonite, for rice straw pretreatment, aiming to enhance biogas production in anaerobic digestion. The photocatalytic pretreatment disrupts rice straw's lignin and hemicellulose structures, reducing silica content for improved microbial degradation. Five 2 L anaerobic digesters were employed with rice straw as the substrate and co-digestion materials, including cow dung and food waste. Rice straw treated with the g-C3N4/7.5% SiO2/5% Bentonite catalyst exhibited a remarkable 37% increase in methane yield compared to untreated rice straw. This photocatalytic process led to a 31% increase in cellulose content and a 30% reduction in lignin after 6 hours of pretreatment. Simultaneously, silica content in the rice straw decreased to 6.4% after 6 hours, resulting in a 48% increase in the carbon proportion. These findings underscore the potential of integrated photocatalysts for significantly enhancing biogas production efficiency through the pretreatment of lignocellulosic biomass.

Towards a sustainable energy future: Evaluating Arundo donax L. in continuous anaerobic digestion for biogas production

AbstractIn response to the EU's REPowerEU initiative (COM (2022) 108) which encourages an increase in biogas production by 20% in member states by 2030 to boost energy independence, it has become essential to identify sustainable alternatives to traditional feedstocks for biogas production, especially in the EU Member states where there is still high dependence on corn silage as the main raw material in biogas plants. While corn silage, predominantly used in the European biogas plants today, serves primarily for the livestock sector, alternative sources need to be explored. Therefore, this study aimed to evaluate the potential of Arundo donax, a perennial energy crop, as an alternative feedstock in a continuous anaerobic process. The biogas yield and its quality, characterized by CH4, CO2, H2S and O2 content, were determined during a continuous process with A. donax, compared with two mixed feedstocks of A. donax and corn silage over a 5‐month period in a continuous anaerobic digestion process. The results revealed that A. donax exhibits a biogas yield and methane content comparable to corn silage, indicating its potential as a viable and sustainable alternative feedstock for biogas production.

Automatised Bioreactor to Produce Biogas from Biomass: Development and Evaluation

Brazil's abundant biomass from agricultural and industrial activities offers significant potential for biogas production, aligning with the ONU Sustainable Development Goals. This study aims to explore anaerobic digestion for biogas production from biomass, investigating key factors influencing the process and advancing efficient technologies. A literature review utilizing biogas as a sustainable energy source was conducted, and an Arduino-controlled bioreactor was built to automatically monitor and control crucial variables in anaerobic digestion, ensuring high-quality and efficient biogas production. The developed bioreactor efficiently enabled continuous tracking of pressure, temperature, hydrogen, and methane in the bioreactor, contributing to energy transition and decarbonization.

EXPLORING THE POTENTIALS OF CEREAL FOOD WASTE IN ANAEROBIC DIGESTION

Cereal food waste makes up a significant part of municipal solid waste, and its proper treatment has become an urgent issue due to its increasing generation. In Nigeria, where around 50% of municipal waste is organic, this study focuses on the need for effective waste management. It highlights the negative environmental and economic impacts of improper disposal methods. The study examines the potential of using cereal food waste in anaerobic digestion for biogas production. Cereal food waste was collected from student hostels at the College of Nursing and Midwifery Malumfashi, sorted, and converted into a composite for anaerobic digestion. An anaerobic digester was constructed using a 25-litre plastic container designed for batch loading. The anaerobic digestion process was carried out for 30 days. The results show that a total biogas volume of 14,634 mL was produced during this time. The daily biogas yields varied, reaching its highest point on the 5th day. This finding underscores the importance of addressing food waste in the cereal supply chain to ensure sustainable food production and consumption. The results demonstrate that cereal food waste has significant potential for biogas production, which can contribute to sustainable waste management and help address environmental challenges linked to food waste. Based on these findings, the study recommends promoting the use of biogas technology to improve food waste management, thus enhancing environmental sustainability and supporting economic development.

Biogas production prediction model of food waste anaerobic digestion for energy optimization using mixup data augmentation-based global attention mechanism.

Achieving rapid, efficient, and cost-effective anaerobic digestion (AD) of food waste is a key means to improve the efficiency of food waste treatment. However, in view of the shortage of historical anaerobic digestion data, the limitation of general neural networks in predicting biogas production, and its sensitivity to abnormal variation points, achieving accurate prediction of biogas production is not easy. This paper proposes a novel biogas production prediction model of food waste AD for energy optimization based on the mixup data augmentation integrating an improved global attention mechanism long short-term memory (LSTM). Taking the AD data of the actual factory as samples, the mixup data augmentation is introduced to generate virtual samples with the similar distribution as original samples. Then original samples and generated virtual samples are used as the input of the global attention mechanism LSTM to establish the food waste AD biogas production prediction model. Finally, the proposed method is applied in the biogas production prediction of actual food waste treatment plants. Compared with other industrial modeling models, the experimental results show that the proposed method has the highest prediction accuracy of 0.988, which performs well in predicting biogas production and can effectively guide and timely adjust feed configuration of AD plants.

Research progress and perspectives of biogas production from municipal organic solid waste

Abstract Anaerobic digestion is a prevailing technology for the treatment and utilization of municipal organic solid waste (MOSW). In this technology, the macromolecular organic matter in waste degrades into small molecular substances through the anaerobic decomposition of microorganisms, producing biogas that can provide enormous energy. This paper focuses on the research progress of anaerobic digestion of various organic wastes for biogas production. The principle and process of anaerobic digestion for biogas production are introduced, along with the key factors affecting anaerobic digestion efficiency, such as temperature, pH, and sealing conditions. At the same time, the current cycle treatment technology and comprehensive treatment system of MOSW are also summarized. Furthermore, the paper explores biogas purification technologies, including desulfurization, deoxidation, drying, and decarbonization. Finally, the state-of-the-art of the utilization of MOSW for biogas production in the world and the problems faced by the utilization of MOSW for biogas production in China are reviewed. By summarizing the anaerobic digestion technology of MOSW, this review hopes to provide some reasonable solutions for the high-value utilization of MOSW.

Current advances in the brewery wastewater treatment from anaerobic digestion for biogas production: A systematic review

Current advances in the brewery wastewater treatment from anaerobic digestion for biogas production: A systematic review

Optimization of distillery-sourced wastewater anaerobic digestion for biogas production

Distillery industries in Ethiopia produces large volumes of high-strength, acidic, recalcitrant, and colored wastewater from sugarcane molasses-based alcohol distilleries. Interestingly, distillery wastes are high in organic nutrients that facilitate microbial growth and serve as substrates for renewable energy production. Conversely, energy insecurity is a major issue in the country, as access to modern energy services is limited in many parts of the country, particularly in rural areas. To address both challenges simultaneously, this study investigated the effects of temperature, pH, and retention time on distillery-sourced wastewater anaerobic digestion for biogas production. A Box-Behnken design confirmed that retention time influenced biogas production and biomethane yield largely. The numerical optimization of the process determined that the optimal conditions for specific biogas production (SBP) and biomethane yield were 31.21 °C temperature, 7.35 pH, and 16.85 days retention time. At this optimal point, the predicted values of SBP and biomethane yield were 0.469 l/g-COD removed and 57.87, respectively. The error percentages between experimental and predicted values were 1.71 % for SBP and 1.57 % for biomethane yield, suggesting the accuracy and predictability of the models. The study findings imply that simultaneous distillery waste treatment and energy production could be a viable option for providing affordable and clean energy to rural communities and small businesses in Ethiopia.

Enhancing biogas production in anaerobic digestion of MSW with addition of bio-solids and various moisture sources

This study aimed to investigate the influence of moisture content on the anaerobic digestion of municipal solid waste (MSW) with the addition of leachate, tap water, wastewater, and sewage sludge. To accomplish this, ten sets of batch experiments were conducted to examine the impact of these various moisture sources on the rate of degradation, indicated by cumulative biogas yield, volatile solids (VS) and total solids (TS) removal. The addition of sludge with leachate and wastewater to MSW resulted in biogas yields that were approximately 30 % higher than the biogas yield from MSW and wastewater alone. Based on the observations of VS removal, it was observed that the addition of sludge degraded about half of the substrate. Therefore, it was observed that the addition of 10 % sludge with leachate and wastewater to MSW provides the best outcomes. The lowest biogas yield was observed with the mixing of tap water with MSW. Further, it was determined that the optimal moisture content for MSW degradation should be greater than 75 % of field capacity (FC). The cumulative biogas yield decreased by more than 50 % when the moisture contents decreased from 100 % to 50 % of FC. The reduction in biogas production at low moisture contents is attributed to limited mass transfer, and the hydrolysis rate also slightly decreases with an increase in total solids. The kinetic study was also carried out using the first order, modified Gompertz, Transference, and Logistic models, and the predicted cumulative biogas yield was compared with the experimental data. The modified Gompertz and Logistic models showed the best fit (R2 ≥ 0.994) with the experimental data for all the sets. The sludge, leachate, and wastewater are produced in large quantities in developing countries, and this study may provide a possible utilization strategy of these wastes for accelerated degradation of MSW.

Performance of a solar greenhouse-biogas hybrid dryer for dehydration of water hyacinth (Eichhornia crassipes)

The development of a solar greenhouse dryer combined with an anaerobic digester for biogas production can reduce carbon emissions and create zero waste. This paper presents the performance of a solar greenhouse biogas dryer (SGBD) that burns biogas to supplement the drying of water hyacinth. The SGBD has an overall efficiency of 87% for 100 kg of fresh water hyacinth. The auxiliary heating system enabled the SGBD to achieve drying temperatures of 24.5 to 45.0 degrees during cloudy and rainy days and produce high quality dried products. There was a fivefold increase in drying capacity and a reduction in drying time of six hours (38%) using the SGBD. End users of the dried product judged it to have improved consistency in color and shape. The SGBD cost less than US$3800 to build with a payback period of five months. This design demonstrates a low-cost and simple technology for small businesses.

Effect of Ultrasonic Pre-treatment on Cow dung Slurry with Sludge Water, Food Waste for Biogas Production in Anaerobic Digesters and Result Validation using Response Surface Methodology

Effect of Ultrasonic Pre-treatment on Cow dung Slurry with Sludge Water, Food Waste for Biogas Production in Anaerobic Digesters and Result Validation using Response Surface Methodology

Analogous study of cumulative biogas production by anaerobic digestion of sewage treatment plant sludge, the proposal of universal dimensionless models

AbstractThe current global concern is how to replace polluting fossil fuels with sustainable green fuels. On this basis, in this study, a characterization protocol for sewage sludge in Algeria was carried out. Their objective was to study the process of anaerobic digestion for biogas production by analogy to experiments that have already been made in the literature. The performance of the proposed models has been validated with experimental data from the scientific literature. Biodegradable organic matter levels are high (160–500 mg L−1) giving an acceptable yield for biogas production. The modeling of cumulative biogas production was carried out by Gompertz and models were proposed for different products. It has been observed that there is a better agreement of the models proposed with the experimental data with a maximum value of r2 = 0.9996. The modeling of the degradation of organic matter was carried out by the first order‐model, and dimensionless models were proposed. The latter gave a good agreement with the experimental data better than the model in the literature, with a maximum value of r2 = 0.9985. The proposed models to study the anaerobic digestion process of organic matter, as well as those related to the process of cumulative biogas production, are universal (without units of measurement), which will help producers in this field to improve production, as well as reduce the investment cost through preliminary simulations.

Effects of oxytetracycline on mesophilic and thermophilic anaerobic digestion for biogas production from swine manure

Anaerobic digestion (AD) technology is a valuable method for producing biogas fuels and treating livestock wastes such as swine manures concurrently. However, the effect of emerging antibiotics on the AD process is still undiscovered. In this study, the influence of oxytetracycline (OTC) on the AD process was investigated under mesophilic (35 ± 0.5 °C) and thermophilic (55 ± 0.5 °C) conditions, respectively. The presence of OTC significantly inhibited the production of methane in AD process, where the methane yields decreased by 58.6% and 73.3% in mesophilic and thermophilic ADs when the initial concentration of OTC was 400 mg/L, respectively. Besides, OTC can be markedly degraded by the AD process with a removal efficiency higher than 90% when the OTC initial concentration is lower than 10 mg/L. Furthermore, a higher concentration OTC led to a lower biomethane yield, energy conversion efficiency, and contaminant removal during both mesophilic and thermophilic ADs. With adding of 400 mg/L OTC, Clostridium sensu stricto 1 (32.9%) and Anaerolinea (29.3%) are dominant to biodegrade organic matter during mesophilic and thermophilic AD systems. Correspondingly, Methanosaeta was functional in producing biomethane in both mesophilic (60.8%) and thermophilic (56.4%) AD systems. Additionally, Methanolinea was bearable to high concentrations of OTC during mesophilic and thermophilic AD processes.

Land cover changes with the development of anaerobic digestion for biogas production in France

AbstractAnaerobic digestion is developing in various countries worldwide to produce renewable energy. In addition, the resulting digestates provide readily available nutrients when applied to cropping systems as fertilizers. The introduction of a biogas plant on a farm can induce land cover changes, in relation to the production of feedstock for the biogas plant and/or to the modification of the farming system. The aim of this study was therefore to characterize and quantify the land cover changes in farms associated with biogas plants in France. We combined two national spatialized databases: the Land Parcel Identification System (yearly French land cover at the parcel scale with farm identifier per parcel) and the SINOE database (biogas plant location and year of start‐up). We showed that, on average, the changes were limited, with an increase in maize areas (+3.4% of the total farm areas) compensated by a decrease in wheat and rapeseed areas (−1.8% and −1.9%, respectively), but with a certain variability. The French regulation and market limiting the use of dedicated energy crops seems to have limited land cover changes in France compared to other countries. However, we elaborated a typology of land cover changes and characterized five clusters of farms across the country. The main one (67% of the farms) corresponded to unchanged land cover after the introduction of a biogas plant. The four other clusters showed contrasting changes, for example, an increase or a decrease in grassland areas, a strong increase in maize areas, or a replacement of winter wheat by winter barley. The diversity and the driving factors behind these changes deserve to be better studied and understood through further farmer surveys.

Ultrasonication-enhanced biogas production in anaerobic digestion of waste active sludge: A pilot scale investigation

In this study, long-term pilot experiments were conducted to investigate the effects of ultrasonication (US) pretreatment on anaerobic digestion (AD) performance. Life cycling assessment (LCA) was used to assess energy efficiency and environmental impacts. With the response to 90-s US at 0.8 W/mL, the soluble COD concentrations increased by 359.0%, whereas the sludge particle size decreased by 56.7%. The positive effects of US increased biogas production by 15.0% and 25.6% at raw sludge VS/TS averages of 0.60 and 0.43, respectively. LCA results indicated that energy neutralization for US-AD was feasible, with a total energy balance of 461.3 kW·h/t DS because of increased energy recovery. The use of US pretreatment allowed for a more diverse microbial community in AD, thereby improving resilience to environmental fluctuations. Unfortunately, US-AD exhibited weak efficiency in inactivating pathogens and antibiotic resistance genes (ARGs), and US could hardly improve the AD control of pathogens carrying ARGs.

A comparative study on polyaluminum chloride (PACl) and Moringa oleifera (MO) chemically enhanced primary treatment (CEPT) in enhanced biogas production: anaerobic digestion performance and the Gompertz model.

A comparative study was performed to estimate biogas production from sludge produced by organic and inorganic chemically enhanced primary treatments (CEPTs). To this end, the effects of two coagulants, polyaluminum chloride (PACl) and Moringa oleifera (MO), on CEPT and biogas production in anaerobic digestion were surveyed within an incubation period of 24 days. The optimal dosage and pH of PACl and MO were optimized in terms of sCOD, TSS and VS parameters in the CEPT process. Next, the digestion performance of anaerobic digestion reactors fed with sludge obtained from PACl and MO coagulants at a batch mesophilic reactor (37 ± 1 °C) was surveyed from the biogas production, volatile solid reduction (VSR) and Gompertz model. At the optimal conditions (pH = 7 and dosage = 5 mg L-1), the removal efficiency of COD, TSS and VS in CEPT assisted with PACL was 63, 81 and 56%, respectively. Moreover, CEPT assisted with MO led to the removal efficiency of COD, TSS and VS until 55, 68 and 25%, respectively. The highest methane yield (0.598 L gVS removed-1) was obtained in an anaerobic digestion reactor with sludge from the MO coagulant. The anaerobic digestion of CEPT sludge instead of primary sludge resulted in higher sCOD removal efficiency, and 43-50% of sCOD was observed compared with the removal of 32% for the primary sludge. Furthermore, the high coefficient of determination (R2) demonstrated the trustworthy predictive precision of the modified Gompertz model with actual data. The combination of CEPT and anaerobic digestion, especially using natural coagulants, provides a cost-effective and practical way to increase BMP from primary sludge.