Anaerobic Digestion Of Kitchen Waste Research Articles

A method for predicting methane production from anaerobic digestion of kitchen waste under small sample conditions.

Anaerobic digestion (AD) has the great potential to treat organic waste and achieve remarkable results effectively. However, it is very tough to establish an accurate mechanistic model for this process. Data-driven modeling technology has opened a new door to solving this problem. While when the sample set is small, traditional data-driven modeling methods are often powerless. In this paper, an effective method is proposed for data-driven high-precision modeling in small sample scenarios. A time series generative adversarial network (TimeGAN) is first utilized to augment the original high-quality small-sample data collected during the AD methane production. A novel hybrid kernel extreme learning machine (HKELM) is then designed to form a better structure of the data-driven model, whose regularization coefficient C0 is optimized by the sparrow search algorithm (SSA). Finally, this semi-finished model (SSA-HKELM) is trained by the augmented data to form the final mathematical model (TimeGAN-SSA-HKELM) for the AD methane generation process. Comparative experiments of the methane daily production prediction error haveverified the effectiveness of the method, which can be extended to other similar small sample data-driven modeling scenarios.

Evolution of quorum sensing process and their regulatory role on biochemical metabolism during the organic loading rate increase in dry anaerobic digestion

The organic loading rate (OLR) is a critical parameter affecting the stability of dry anaerobic digestion (AD) of kitchen waste (KW), and significantly impacting the variations in physicochemical parameters and microbial communities. However, the evolution of quorum sensing (QS) and their role on anaerobic biochemical metabolism during the increase in OLR in dry AD remain unknown. Therefore, this study systematically elucidated the matter through multi-omics analysis based on a pilot-scale dry AD of KW. The results demonstrated that fluctuations in the OLR significantly influenced the microbial QS in dry AD. When the OLR ≤4.0 g·VS/L·d, the system operated stably, and methane production increased. The enrichment of Proteobacteria was crucial for sustaining high levels of functional genes associated with various types of QS, including acyl-homoserine lactones (AI-1), autoinducer-2 (AI-2), autoinducer-3 (AI-3), and gamma-aminobutyric acid (GABA). This enabled cooperative communication among microbes under low OLR. Furthermore, most genes associated with these QS processes positively affected hydrolysis, acidogenesis, and methanogenesis. When the OLR increased to 6.0 g·VS/L·d, the fatty acids and hydrogen partial pressure increased significantly. The autoinducing peptides (AIP)-type became the predominant QS and was positively correlated with fatty acids abundance. Syntrophaceticus and Syntrophomonas may promote syntrophic oxidation of acetate at high OLR through AIP-type QS. These findings provided new insights into the QS processes of microbes during dry AD of KW and a theoretical foundation for optimizing biochemical metabolic processes in dry AD through QS.

Preparation of bacterial fertilizer from biogas residue after anaerobic co-digestion of kitchen waste and residual sludge.

Azotobacter chroococcum and Bacillus subtilis were selected as fermentation strains, and biogas residue after anaerobic digestion of kitchen waste and residual sludge was used as fermentation substrate. A single factor optimization test was used to optimize the solid-state fermentation parameters of biogas residue with the number of viable bacteria and the number of spores as indexes. The results showed that the optimum inoculation conditions involved the following: 55% initial moisture content, 15% initial inoculation amount, 30 ℃, and 1:1 initial inoculation ratio for 13days. Pot experiment showed that the prepared three kinds of bacterial fertilizers could not only effectively promote the growth of white clover, improve the composition of soil nutrients, but also change the structure of soil bacterial community, which is of great significance to the health of soil ecosystem in white clover.

Effects of biochars derived from different feedstocks and pyrolysis temperatures on the anaerobic digestion of kitchen waste

The aim of this work was to investigate the effects of biochars derived from different feedstocks and pyrolysis temperatures on the anaerobic digestion (AD) of kitchen waste (KW). Nine biomass feedstocks (corn straw (CS), Dicranopteris dichotoma (DD), bamboo (B), KW, tea residues (TR), mushroom cultivation waste (MW), cassava lees (CL), Chlorella (C), and sargassum (S)) were pyrolyzed at different temperatures (300 °C, 500 °C, and 800 °C). Biochar varied in physicochemical properties (e.g., specific surface area, total pore volume, and organic functional group) depending on both feedstock type and pyrolysis temperature. This further impacted the enrichment of functional microbial consortia and development of methanogenic pathways, resulting in a varied AD performance. The addition of biochars generated respectively from CS, MW, and S at 800 °C, 300 °C, and 500 °C significantly improved the maximum methane production rate (Rm) and methane yield, while other biochars enhanced either Rm or methane yield. Therefore, the efficacy of biochar on methanogenesis associated with both the feedstock type and pyrolysis temperature. The findings offer a beneficial reference for the selection and application of biochar to improve the AD performance.

Co-production and enhancement of biogas and biohydrogen by optimizing NaOH-urera pretreatment conditions for kitchen waste

Kitchen waste (KW) constitutes a major portion of municipal solid waste, posing an imminent environmental challenge. Given its high water and organic content, KW is suitable for Anaerobic Digestion (AD) prior to its disposal, as it reduces Chemical Oxygen Demand (COD) and simultaneously generates biogas. The unique contribution of this study is the investigation of NaOH-urea pretreatment as a method to enhance AD of KW and sludge, ultimately leading to more efficient and environmentally friendly waste disposal. NaOH-urea pretreatment is selected for its ability to improve hydrolysis, increase organic matter solubilization, and enhance nutrient balance, ultimately boosting biogas yield during AD. Response surface methodology (RSM) was used for optimizing pretreatment conditions. AD experiments were performed batch-wise. For optimization, pretreatment time, temperature, and NaOH-urea concentration were selected as independent variables. RSM results indicated that optimum NaOH-urea concentration, time, and temperature conditions were 30 g/L, 30 min, and −5 °C, respectively. At optimum conditions, cumulative biogas was 316 ml, whereas biohydrogen % (v/v) was 36.21 %. Furthermore, the Modified Gompertz Model (MGM) and Logistic Function Model (LFM) were used to observe the efficacy of NaOH-urea pre-treatment of KW., The reaction kinetics were also discussed. Akaike's Information Criterion was employed to determine which model best fits the obtained experimental data. It was found that MGM is better than LFM for this study. Through experimental investigations and numerical modeling, this research provides insights into optimizing biogas and biohydrogen production from KW.

PROPOSED BY DISPOSAL OF MUNCIPAL SOLID WASTE BY BIO METHANATION IN GADHINGLAJ CITY

In India Bio-Methanation in conventional biogas plant have been proposed as one of the appropriate alternative sources of energy which can counter the escalating demand of fossil fuels. In India large quantity of waste generates produce per day and hence the noof biogas installation of biogas plant is increasing rapidly and the trend is expected to continue at least for the foreseeable future. Biogas plant like many other energy generating technologies is not free from environmental problem. Biogas production requires anaerobic digestion. The biogas plant creates an organic processing facility to create biogas which will be more cost effective, eco friendly, cut down on landfill waste, generate a high quality renewable fuel and reduce Carbon Dioxide and Methane emission. The anaerobic digestion of kitchen waste produces biogas, which primarily consist of methane (CH4 ) and Carbon Dioxide (CO2). Biogas can be used as energy source and also for numerous purposes. But any possible application requires knowledge and information about composition and quantity of constituent in the biogas produced.

Enhancing kitchen waste anaerobic digestion by recycled aluminum industry waste: Alkali treatment and potential electron transfer mechanism

Kitchen waste has become a significant environmental concern worldwide. Red mud, an industrial solid waste characterized by its porous structure and high iron oxide content, exhibits potential as a conductive conduit in the direct interspecies electron transfer (DIET) pathway. In this study, red mud pretreatment of kitchen waste was conducted to enhance anaerobic digestion (AD). The effect and mechanism of enhancing kitchen waste AD by red mud pretreatment was studied for the first time. Results indicated that red mud pretreatment could accelerate the hydrolysis of organic compounds and alleviate the acid inhibition. Consequently, the methane production rate was increased from 260.7 mL/g VS to 402.3 mL/g VS, i.e., up to 54.3%. And volatile solids removal efficiency was increased from 53.9% to 73.1%, i.e., up to 35.6%. Furthermore, microbial community analysis revealed the enrichment of electrochemically active bacteria (Synergistaceae), acetogenic bacteria (Syntrophomonadaceae) and methanogens (Methanobacterium and Methanosarcina), which played essential roles in interspecies hydrogen transfer (IHT) and DIET. This study showed that red mud pretreatment has the potential to enhance kitchen waste AD which contributes to carbon mitigation. It also threw the potential new insights to the relative mechanism.

Preparation of iron oxide-modified digestate biochar and effect on anaerobic digestion of kitchen waste

Two kinds of Fe2O3-modified digestate-derived biochar (BC) were prepared and their effects on anaerobic digestion (AD) of kitchen waste (40.0 g VS/L) were investigated, with BC and Fe2O3 addition used as a comparison. The results showed that Fe2O3-modified BC (Fe2O3-BC1 prepared by co-precipitation and Fe2O3-BC2 by impregnation) significantly increased methane yield (20.8 % and 16.4 %, respectively) and reduced volatile fatty acid concentration (35.6 % and 29.6 %, respectively). Microbial high-throughput analysis revealed that Fe2O3-modified BC selectively enriched Clostridium (47.3 %) and Methanosarcina (72.2 %), suggesting that direct interspecies electron transfer contributing to improved biogas production performance was established and enhanced. Correlation analysis indicated that biogas production performance was improved by the larger specific surface area (83.4 m2/g), pore volume (0.101 cm3/g), and iron content (97.4 g/Kg) of the BC. These results offer insights for enhancing the efficacy of AD processes using Fe2O3-modified BCs as additives.

Effects of different acidification-resisting strategies on anaerobic digestion of kitchen waste: Methanogenic properties and microbial community shift

Anaerobic digestion (AD) has been widely used as a promising technology for the treatment of kitchen waste (KW). The effects of several acidification-resisting methods were compared, which included the supplementation of trace elements (TEs) and zero-valent iron (ZVI) / powdered activated carbon (PAC), and the application of the sludge domesticated by acetic acid (HAc) and KW as inoculum. The results showed that the supplementation of TEs and ZVI/PAC at total solid (TS) content of 6% and optimal addition doses resulted in an increase in methane yield to 346 and 366 mL/g VS, respectively. In addition, the methane yields of 327 and 241 mL/g VS were obtained by applying the sludge domesticated with KW and HAc as inoculum, while the methane yield of the control was only 89.2 mL/g VS, representing a relative increase of 288%, 311%, 267%, and 170%. The acidification could be alleviated by applying these methods, and also the methanogenic profile was improved. Furthermore, microbial community analysis revealed that the enrichment of Methanosarcina, which enhanced the substrate utilization capacity and subsequently increased methane production, was achieved through the addition of TEs and ZVI/PAC, along with the application of sludge domesticated by KW.

Biogas slurry reflux enhances the organic loading rate of high-solid anaerobic digestion of kitchen waste by alleviating fatty acids accumulation

The inhibition of fatty acids metabolism is a key limiting factor for organic loading rate (OLR) enhancement during the high-solid anaerobic digestion (HSAD) of kitchen waste (KW). Biogas slurry reflux (BSR) has been demonstrated to enhance system stability and biogas production. However, the mechanism through which BSR modulates fatty acids metabolism, thereby increasing OLR, remains unclear. Therefore, by conducting thermodynamic evaluation and multi-omics analyses, this study explored the feasibility of BSR for enhancing OLR in HSAD and its regulatory role in fatty acids metabolism throughout a semi-continuous long-term (363-day) pilot experiment. In the first OLR increase stage, the system operated stably when the OLR was below 6.0 g·VS/L·d, and the average daily methane yield exceeded 400 mL/g VS. Moreover, functional genes related to fatty acids degradation were enriched. However, fatty acids metabolism was inhibited at an OLR of 6.0 g·VS/L·d, resulting in a noticeable accumulation of fatty acids, leading the system to the brink of collapse. Notably, the implementation of BSR promoted an OLR increase, reaching levels of 7.5 g·VS/L·d. Thermodynamic analyses demonstrated that BSR promoted the thermodynamic degradation of propionate and butyrate under equivalent OLR conditions. Particularly, BSR enhanced the enrichment of Syntrophaceticus and Syntrophomonas, thereby promoting syntrophic acetate oxidizing-hydrogenotrophic methanogenesis. Metagenome and metabolome analyses suggested that BSR promoted medium and long-chain fatty acids degradation and methanogenesis under high OLR (OLR exceeding 6.0 g·VS/L·d). These findings provide systematic insights into the regulation of fatty acids biochemical metabolism through BSR, thus promoting an increase in OLR within plug-flow HSAD.

Effect of alkali pretreatment time on kitchen waste anaerobic digestion performance enhanced by alkali pretreatment combined with bentonite: performance enhancement, microbial community structure, and functional gene analysis.

Kitchen waste was mainly composed of carbohydrates, lipids, and proteins. Anaerobic digestion (AD) of kitchen waste usually occurred acidification and further deteriorated. In our previous study, alkali pretreatment combined with bentonite (AP/Be) treatment was proved to enhance high solid AD of kitchen waste. However, effects of AP time on AP/Be were not yet studied. This study investigated the effects of AP time on AP/Be treatment on enhancing high solid AD. The results showed that compared with the control group, the cumulative methane production rate could be increased by 3.30 times (149.7mL CH4/g VS) and the volatile solids (VS) reduction rate increased by 63.36%. Microbial community analysis showed that the relative abundance of Methanosarcina and Methanosaeta were increased from 6.49 and 7.83% to 47.14 and 16.39% respectively. Predictive functional analysis showed that AP/Be treatment increased the abundance of energy production and conversion, coenzyme transport, and metabolism. This study revealed the potential mechanism of AP/Be enhanced kitchen waste AD performance and AP/Be was a potential strategy to strengthen AD.

Enhancing High Solid Anaerobic Digestion of Kitchen Waste with Red Mud Addition: Performance and Microbial Community

Enhancing High Solid Anaerobic Digestion of Kitchen Waste with Red Mud Addition: Performance and Microbial Community

A change in substance and microbial community structure during the co-composting of kitchen waste anaerobic digestion effluent, sewage sludge and Chinese medicine residue

Anaerobic digestion is a resource recovery method for organic waste, gaining attention due to carbon reduction. Disposing of anaerobic digestion effluent (ADE) is crucial for developing anaerobic digestion, but conventional wastewater treatment fails to effectively recover nutrients contained in the ADE. In the present study, the ADE without solid-liquid separation was mixed with sewage sludge and Chinese medicine residue for the composting, where the ADE could be recovered at high temperature through humification. Besides, the nitrogen balance, humification process, and microbial dynamics during the composting process were studied. The results showed that the group supplemented with ADE could increase the nitrogen retention efficiency by 2.21 % compared to the control group. High ammonia nitrogen content and salinity did not negatively affect the maturity and phytotoxicity of compost products and even increase the humification degree of compost products. Moreover, additional ADE may not alter microbial community structure, which could contribute to microbial succession. This is the first time to investigate the substance transformation and shift in microbial community structure while applying composting process for ADE treatment, in which the anaerobic-aerobic collaborative disposal process provides an alternative solution for the recovery of ADE.

Deeper Insights into the Effect of Humic Acid on Kitchen Waste Anaerobic Digestion: Enzyme Activities, Microbial Community Dynamics, and Key Metabolic Pathways

Anaerobic digestion (AD) represents one of the most eco-friendly approaches for recovering the energy from kitchen waste (KW). This study investigated the impact of humic acid (HA) on AD of KW. Batch experiments were conducted using KW as the substrate, with varying HA dosages. The results revealed that an increase in HA dosage led to an inhibition of methanogenic efficiency by 29.51% and a delayed start-up of AD. The HA exhibited dual effects on enzyme activities during AD, inhibiting hydrolytic enzymes while stimulating acidogenic enzymes. This unique interaction ultimately resulted in a significant 12.32% increase in volatile fatty acid production. Furthermore, HA induced the generation of reactive oxygen species and had a discernible impact on the activity of the electron transfer system. A bioinformatics analysis highlighted that HA promoted the abundance of microorganisms with mediated interspecies electron transfer ability, including DMER64 and Methanosaeta, as well as the Firmicutes phylum, while significantly reducing the abundance of Methanobacterium. Moreover, the KEGG pathway analysis revealed a decrease in hydrolysis and methanogenesis-related genes and an increase in acidogenesis-related genes.

Digestate Quality Originating from Kitchen Waste

This paper examines the influence of biomass directed to anaerobic digestion on the quality of digestate, specifically focusing on the presence of undesirable substances, such as plastics, including biodegradable ones. It analyses the susceptibility of selected bioplastics to degradation and addresses the problem of reliable identification of microplastics in both feedstock—directed to anaerobic digestion—and produced digestate. The review indicates the advantages of using kitchen waste as a feedstock for anaerobic digestion. The constant availability of kitchen waste as a raw material, its homogeneous composition, and the fact that it is not subjected to seasonal fluctuations, facilitates its management in the anaerobic digestion process. However, to ensure the desired quality of a digestate, it is important to carry the selective collection of waste at the source. The review refers to the issues of quality, materials, and regulations, and it may be useful for readers entering the subject of a material loop, as well as those already involved in the subject, including local government units. Anaerobic digestion of kitchen waste is an important part of a renewable economy, providing year-round constantly available substrate for energy production that is not seasonally dependent.

Impacts of river snails rice noodle ingredients addition on the kitchen waste anaerobic digestion performances, microbial communities and metabolic pathways

With the rapid development of the river snails rice noodle industry, the treatment of the wastewater generated in the production of river snails rice noodle has attracted people’s attention. This study investigated the performance of the anaerobic digestion of kitchen waste with river snails rice noodle ingredients, including key enzyme activities, microbial community distribution and metabolic pathways in the anaerobic reactor. The average chemical oxygen demand removal efficiencies were 92.5% and 88.7% when 130 g and 260 g river snails rice noodle ingredients were added in the anaerobic reactor, respectively. Acetate kinase activity of the sludge decreased during anaerobic digestion, but increased at 35 °C on days 55. The river snails rice noodle ingredients inhibited the growth of Proteobacteria and the expression of methane metabolism. An increase in temperature promoted the presence of Bacteroidetes and Methanothrix (increased by 3.95% and 2.64% respectively). The later stage of experiment demonstrated an increase in the glycolysis rate-limiting enzymes ATP-dependent phosphofructokinase and pyruvate kinase. It was illustrated that the addition of river snails rice noodle ingredients inhibited the processing capacity of the anaerobic digestion reactor, and the increase of operating temperature of anaerobic reactor alleviated the inhibition of higher content river snails rice noodle ingredients on anaerobic digestion process. It was provided valuable basic information for the future study of treatment of river snails rice noodle wastewater.

A Review on Start-Up Phase Optimization of Kitchen Waste Anaerobic Digestion

Kitchen waste has been confirmed as an appropriate substrate for anaerobic digestion, although means of alleviating the difficulties and time-consuming nature of the start-up phase need to be further explored. Based on the mechanism of anaerobic digestion, we discuss the factors influencing the anaerobic start-up phase of kitchen waste. By controlling the temperature, pH, organic loading rate, inoculation ratio and other parameters, the high activity of methane-producing archaea and other bacteria can be intensified, thereby increasing the biogas yield. Furthermore, we introduce the methods of substrate pretreatment, operating condition optimization and conductive material addition. Finally, we put forward future perspectives and research gaps related to accelerating the start-up phase of anaerobic bioreactors utilized for kitchen waste biodegradation.

Effects of upward flow rate and modified biochar location on the performance and microecology of an anaerobic reactor treating kitchen waste.

Increasing the value of food waste through anaerobic digestion is an attractive strategy. Meanwhile, the anaerobic digestion of kitchen waste also faces some technical challenges. In this study, four EGSB reactors were equipped with Fe-Mg-chitosan bagasse biochar at different locations, and the reflux pump flow rate was increased to change the upward flow rate of the reactor. The effects of adding modified biochar at different locations under different upward flow rate on the efficacy and microecology of anaerobic reactors treating kitchen waste were investigated. Results showed that Chloroflexi was the dominant microorganism when the modified biochar was added to the lower, middle, and upper parts of the reactor and mixed in the reactor, accounting for 54%, 56%, 58%, and 47%, respectively, on day 45. With the increased upward flow rate, the abundance of Bacteroidetes and Chloroflexi increased, while Proteobacteria and Firmicutes decreased. It was worth noting that the best COD removal effect was achieved when the anaerobic reactor upward flow rate was v2 = 0.6m/h and the modified biochar was added in the upper part of the reactor, during which the average COD removal rate reached 96%. In addition, mixing modified biochar throughout the reactor while increasing the upward flow rate provided the greatest stimulus for the secretion of tryptophan and aromatic proteins in the sludge extracellular polymeric substances. The results provided a certain technical reference for improving the efficiency of anaerobic digestion of kitchen waste and scientific support for the application of modified biochar to the anaerobic digestion process.

Microbial response behavior to powdered activated carbon in high-solids anaerobic digestion of kitchen waste: Metabolism and functional prediction analysis

Anaerobic digestion (AD) can not only treat organic waste, but also recycle energy. However, high-solids AD of kitchen waste usually failed due to excessive acidification. In this study, the effect of activated carbon (AC) on kitchen waste AD performance was investigated under high-solids conditions (total solids contents = 15%). The results showed that efficiencies of acidogenesis and methanogenesis were promoted in presence of moderate concentration (50 g/L > AC >5 g/L), but high concentration (AC >70 g/L) weakened AD performance. Moreover, AC addition enhanced the methane production rate from 66.0 mL/g VS to 231.50 mL/g VS, i.e., up to 250.7%. High-throughput sequencing results demonstrated that the abundance of electroactive DMER64 increased from less than 1%–29.7% (20 g/L AC). As AC gradually increased，aceticlastic methanogenesis changed to hydrogenotrophic pathway. Predicted functional analysis indicated that AC can enhance abundances of energy and inorganic ion metabolism, resulting in high methane production.

Experimental Study On Production of Biogas from Kitchen Waste

In our institute we have four hostels and all having their own individual mess, where daily a large amount of kitchen waste is obtained which can be utilized for better purposes. Biogas production requires Anaerobic digestion. Project was to Create an Organic Processing Facility to create biogas which will be more cost effective, eco-friendly, cut down on land fill waste, generate a high-quality renewable fuel, and reduce carbon dioxide & methane emissions. Overall, by creating a biogas reactor on campus in the backyard of our hostels will be beneficial. Kitchen (food waste) was collected from different hostels of PACE IT & S Mess as feed stock for our reactor which works as an aerobic digester system to produce biogas energy. The anaerobic digestion of kitchen waste produces biogas, a valuable energy resource Anaerobic digestion is a microbial process for production of biogas, which consist of Primarily methane (CH4) & carbon dioxide (CO2). Biogas can be used as energy source and also for numerous purposes. But any possible applications require knowledge & information about the composition and quantity of constituents in the biogas produced. The continuously-fed digester requires addition of sodium hydroxide (NaOH) to maintain the alkalinity and pH to 7. For this reactor we have prepared our Inoculum than we installed batch reactors, to which inoculum of previous cow dung slurry along with the kitchen waste was added to develop our own Inoculum. A combination of these mixed inoculum was used for biogas production at 37°C in laboratory (small scale) reactor (20L capacity) In our study, the production of biogas and methane is done from the starch-rich and sugary material and is determined at laboratory scale using the simple digesters.