Comparative study on the effects of anionic, cationic, and nonionic polyacrylamide surface modified magnetic micro-particles (MMP) for anaerobic digestion treatment of vegetable waste water (VWW).

Anaerobic digestion provides a solution for the treatment of vegetable waste water (VWW), but there are currently limited targeted treatment methods available. Building upon previous studies, this research investigated the effects of polyacrylamide-modified magnetic micro-particles (MMP) on anaerobic digestion (AD) of VWW. Three variations of these particles were created by grafting anionic, cationic, and non-ionic polyacrylamide (PAM) onto the MMPs' surfaces, resulting in aPAM-MMP, cPAM-MMP, and nPAM-MMP, respectively. In AD experiments, the addition of aPAM-MMP notably enhanced the degradation of chemical oxygen demand (COD) in VWW. COD decreased to 1290 mg/L in the reactor with aPAM-MMP by day 12 and remained low, while the other reactors had COD concentrations of 4137.5, 5510, and 3010 mg/L on the same day, decreasing thereafter. This modification also improved the production and utilization of hydrogen gas and volatile fatty acids (VFAs), along with the conversion of methane. When tested for bioaffinity using fluorescent GFP-E.coli bacteria, the aPAM-MMP, cPAM-MMP, and nPAM-MMP demonstrated increases in fluorescence intensity by 51.66%, 36.13%, and 37.02%, respectively, compared to unmodified MMP when attached with GFP-E.coli. Further analyses of microbial community revealed that the reactor with aPAM-MMP had the highest microbial richness and enriched bacteria capable of organic matter degradation, such as Bacteroidota, Synergistota, Chloroflexi, Halobacterota phyla, and Parabacteroides, Muribaculaceae, and Azotobacter genera. In conclusion, our experiment verifies that APAM-MMP promotes anaerobic treatment of VWW and provides a novel reference point for enhancing VWW degradation.

Unraveling the relationship between soil carbon-degrading enzyme activity and carbon fraction under biogas slurry topdressing.

Biogas slurry, a by-product of the anaerobic digestion of biomass waste, predominantly consisting of livestock and poultry manure, is widely acclaimed as a sustainable organic fertilizer owing to its abundant reserves of essential nutrients. Its distinctive liquid composition, when tactfully integrated with a drip irrigation system, unveils immense potential, offering unparalleled convenience in application. In this study, we investigated the impact of biogas slurry topdressing as a replacement for chemical fertilizer (BSTR) on soil total organic carbon (TOC) fractions and carbon (C)-degrading enzyme activities across different soil depths (surface, sub-surface, and deep) during the tasseling (VT) and full maturity stage (R6) of maize. BSTR increased the TOC content within each soil layer during both VT and R6 periods, inducing alterations in the content and proportion of individual C component, particularly in the topsoil. Notably, the pure biogas slurry topdressing treatment (100%BS) compared with the pure chemical fertilizer topdressing treatment (CF), exhibited a 38.9% increase in the labile organic carbon of the topsoil during VT, and a 30.3% increase in the recalcitrant organic carbon during R6, facilitating microbial nutrient utilization and post-harvest C storage during the vigorous growth period of maize. Furthermore, BSTR treatment stimulated the activity of oxidative and hydrolytic C-degrading enzymes, with the 100%BS treatment showcasing the most significant enhancements, with its average geometric enzyme activity surpassing that of CF treatment by 27.9% and 27.4%, respectively. This enhancement facilitated ongoing and efficient degradation and transformation of C. Additionally, we screened for C components and C-degrading enzymes that are relatively sensitive to BSTR. The study highlight the advantages of employing pure biogas slurry topdressing, which enhances C component and C-degrading enzyme activity, thereby reducing the risk of soil degradation. This research lays a solid theoretical foundation for the rational recycling of biogas slurry.

A novel integrated single-stage anaerobic co-digestion and oxidation ditch-membrane bioreactor system for food waste management and building wastewater recycling.

This study is to develop a novel integrated single-stage anaerobic co-digestion and oxidation ditch membrane bioreactor (SAC/OD-MBR) for food waste and building wastewater recycling. The co-digestion of food waste (FW) from a canteen with waste sludge (WS) from OD-MBR was performed with the proportion of FW:WS at 10:1 by weight. The liquid digestate from the co-digestion process was further co-treated with building wastewater in the OD-MBR system for water reuse purpose. Maximum methane content of 65.2% in biogas as well as average specific methane yield of 0.24 gCH4/gVS could be obtained with anaerobic co-digestion of food waste and waste sludge from OD-MBR with HRT of 24 h and horizontal flow velocity of 0.3 m/s. The observed main methanogen species in this co-digestion process were Methanoculleus bourgensis and Methanoculleus palmolei. For co-treatment of liquid digestate and building wastewater with the OD-MBR, it was found that HRT of 24 h and horizontal flow velocity of 0.3 m/s could achieve highest COD and nitrogen removal efficiencies. HRT can be considered as a main key parameter to promote nitrification activity inside the OD-MBR system. Moreover, treated effluent from the SAC/OD-MBR could comply with the water reuse standard for garden and landscape application in the university campus. Furthermore, the techno-economic analysis indicates that this proposed system has a high potential of total cost savings and other indirect benefits. Therefore, the prototype SAC/OD-MBR can be an alternative system for food waste management and wastewater recycling for building application.

Biogas production estimation using data-driven approaches for cold region municipal wastewater anaerobic digestion.

The objective of this study was to estimate biogas (including methane, carbon dioxide and hydrogen sulphide) production rates from the anaerobic digesters at the Saskatoon Wastewater Treatment Plant (SWTP), Saskatchewan, Canada. Average daily ambient temperatures typically fluctuate between -40 °C and 30 °C over the year making the management of the SWTP processes challenging. Operating parameters were taken from 2014 to 2016 including volatile fatty acids (VFAs), total solids, fixed solids, volatile solids, pH, and inflow rate. The input parameters were processed using two methods including a correlation test and principal component analysis (PCA) to determine highly correlated variables prior to use in models. The two models used to estimate biogas production rates are a multi-layered perceptron feed forward artificial neural network (ANN) and an adaptive network-based fuzzy inference system (ANFIS) with grid partition (GP), subtractive clustering (SC) and fuzzy c-means clustering (FCMC). The models using PCA processed variables had reasonable performances with shorter model processing times, while reducing model input data. Among various structures of ANN and ANFIS models for estimation of biogas generation, the ANFIS-FCMC results had better agreement with the observed data. Its average approximation of emission rates of CH4, CO2 and H2S from the wastewater digesters were 3,086, 6,351, and 41.5 g/min, respectively. Our group is assessing similar estimation methodology for the remaining SWTP wastewater treatment processes that are more highly impacted by the seasonal temperature variations including primary and secondary treatment processes.

Management of slurry in Gran Canaria Island with full-scale natural treatment systems for wastewater (NTSW). One year experience in livestock farms.

The aim of this work is to describe the performance of three full-scale natural treatment systems for wastewater, which operated in an integrated manner in livestock pig farms (1000-1500pigsintotal) over one year. Slurry management was performed with these natural treatment systems operating under the normal waste loading conditions of the livestock farms in which were integrated. The systems were comprised of elements such as first generation digesters, subsurface flow constructed wetlands and facultative ponds. The facilities, located on the island of Gran Canaria (Spain), enabled the study of viable alternatives for effluent management characterized by low-cost treatments. The systems were evaluated in terms of chemical oxygen demand removal efficiency, operating with variable organic loading. Values of between 80% and 90% were obtained. A comparison was also made of first-generation cascade flow digester operation (<70% removal efficiency), with complete-mix digesters (<20% removal efficiency), and finally with facultative ponds combined with subsurface flow constructed wetlands (<91% removal efficiency). It was also verified that when natural treatment systems for wastewater combine different elements they have better removal efficiency and better response to load and/or flow changes.

Harnessing fungi to mitigate CH4 in natural and engineered systems.

Methane (CH4) is a powerful greenhouse gas emitted from natural and anthropogenic sources, and its emission rates vary among sources as a function of environment, microbial respiration, and feedbacks. Biological CH4 flux from natural and engineered systems is typically represented simply as generation of CH4 by methanogens minus oxidation by methanotrophs. In many cases, however, CH4 flux is modulated by transport and solubility mechanisms that occur before oxidation or other chemical transformation. The ability of fungi to directly oxidize CH4 remains unclear; however, their hydrophobic growths extending above microbial biofilms can improve surface area and sorption of hydrophobic gases. This can improve overall oxidation rates in a biofilm simply by improving phase transfer dynamics and bioavailability to bacterial or archaeal associates. This indirect facilitation is not necessarily intuitive, but there has been a recent emerging interest in harnessing these fungal abilities in engineering bioreactors and filtration systems designed to capture and oxidize CH4. These dynamics may be playing a similar facilitative role in natural CH4 oxidation, where fungi may indirectly influence carbon mineralization and methanogen/methanotroph communities, and/or directly oxidize and dissolve gaseous CH4. This review highlights these unique roles for fungi in determining net CH4 oxidation rates, and it summarizes the potential to harness fungi to mitigate CH4 emissions.

A comparative experimental study of the anaerobic treatment of food wastes using an anaerobic digester with a polyamide stirring rake or a stainless-steel stirring rake.

A low treatment capacity and unstable operation are the main drawbacks of the anaerobic digestion of food wastes. The present work improved the efficiency and stabilization of the anaerobic digestion of food wastes using digesters with a polyamide stirring rake (DPSR) and compared it to a traditional digester with a stainless-steel stirring rake (DSSSR). The DPSR had a higher reliability and produced 3.97 times the methane yield of DSSSR in batch experiments at high loading rates (105 VS/L). Uniform design experiments were applied to investigate the relationship between methane yield and the stirring factors of the DPSR. A regression analysis of the uniform design indicated that stirring factors synergistically affect methane yield. The experiment verifying the optimal conditions showed that in the DPSR with 82 r/min stirring intensity and 10 min/d stirring time, the first 20 days of methane yield (392.1 mL/g VS) achieved to 85.26% of the theoretically derived methane yield. In brief, in the anaerobic digestion of food wastes for high methane production and stable operation, the DPSR was more beneficial for the anaerobic digestion of food wastes than the DSSSR.

Isolation and characterization of new Methanosarcina mazei strains KOR-3, -4, -5, and -6 from an anaerobic digester using pig slurry.

OBJECTIVE: An experiment was conducted to isolate and identify new methanogens in Korea from an anaerobic digester that uses pig slurry. METHODS: An anaerobic digestate sample was collected from an anaerobic digester using pig slurry. Pre-reduced media were used for the growth and isolation of methanogens. Growth temperature range, pH range, NaCl concentration range, substrate utilization, and antibiotic tolerance were investigated to determine the physiological characteristics of isolated methanogens. The isolates were also examined microscopically for their morphology and Gram-stained. Polymerase chain reaction of 16S rRNA and mcrA gene-based amplicons was used for identification purpose. RESULTS: Four strains, designated KOR-3, -4, -5, and -6, were isolated and were non-motile, irregular coccoid, and 0.5 to 1.5 µm in diameter. Moreover, the cell walls of isolated strains were Gram-negative. KOR-3 and KOR-4 strains used acetate for methane production but did not use H2+CO2, formate, or methanol as a growth substrate KOR-5 and KOR-6 strains utilized acetate, methanol, and trimethylamine for methanogenesis but did not use H2+CO2 or formate as a growth substrate. The optimum temperature and pH for growth of four strains were 39°C and 6.8 to 7.2, respectively. The optimum concentration of NaCl for growth of KOR-3, KOR-5, and KOR-6 were 1.0% (w/v). The optimum NaCl concentration for KOR-4 was 0.5% (w/v). All of the strains tolerated ampicillin, penicillin G, kanamycin, streptomycin, and tetracycline; however, chloramphenicol inhibited cell growth. Phylogenetic analysis of 16S rRNA and mcrA genes demonstrated that strains KOR-3, -4, -5, and -6 are related to Methanosarcina mazei (M. mazei, 99% sequence similarity). CONCLUSION: On the basis of physiological and phylogenetic characteristics, strains KOR-3, -4, -5, and -6 are proposed to be new strains within the genus Methanosarcina, named M. mazei KOR-3, -4, -5, and -6.

Co-digestion of agricultural and municipal waste to produce energy and soil amendment.

In agriculture, manure and cotton gin waste are major environmental liabilities. Likewise, grass is an important organic component of municipal waste. These wastes were combined and used as substrates in a two-phase, pilot-scale anaerobic digester to evaluate the potential for biogas (methane) production, waste minimisation, and the digestate value as soil amendment. The anaerobic digestion process did not show signs of inhibition. Biogas production increased during the first 2 weeks of operation, when chemical oxygen demand and volatile fatty acid concentrations and the organic loading rate to the system were high. Chemical oxygen demand from the anaerobic columns remained relatively steady after the first week of operation, even at high organic loading rates. The experiment lasted about 1 month and produced 96.5 m3 of biogas (68 m3 of CH4) per tonne of waste. In terms of chemical oxygen demand to methane conversion efficiency, the system generated 62% of the theoretical methane production; the chemical oxygen demand/volatile solids degradation rate was 62%, compared with the theoretical 66%. The results showed that co-digestion and subsequent digestate composting resulted in about 60% and 75% mass and volume reductions, respectively. Digestate analysis showed that it can be used as a high nutrient content soil amendment. The digestate met Class A faecal coliform standards (highest quality) established in the United States for biosolids. Digestion and subsequent composting concentrated the digestate nitrogen, phosphorus, and potassium content by 37%, 24%, and 317%, respectively. Multi-substrate co-digestion is a practical alternative for agricultural waste management, minimisation of landfill disposal, and it also results in the production of valuable products.

Biologically Produced Methane as a Renewable Energy Source.

Methanogens are a unique group of strictly anaerobic archaea that are more metabolically diverse than previously thought. Traditionally, it was thought that methanogens could only generate methane by coupling the oxidation of products formed by fermentative bacteria with the reduction of CO2. However, it has recently been observed that many methanogens can also use electrons extruded from metal-respiring bacteria, biocathodes, or insoluble electron shuttles as energy sources. Methanogens are found in both human-made and natural environments and are responsible for the production of ∼71% of the global atmospheric methane. Their habitats range from the human digestive tract to hydrothermal vents. Although biologically produced methane can negatively impact the environment if released into the atmosphere, when captured, it can serve as a potent fuel source. The anaerobic digestion of wastes such as animal manure, human sewage, or food waste produces biogas which is composed of ∼60% methane. Methane from biogas can be cleaned to yield purified methane (biomethane) that can be readily incorporated into natural gas pipelines making it a promising renewable energy source. Conventional anaerobic digestion is limited by long retention times, low organics removal efficiencies, and low biogas production rates. Therefore, many studies are being conducted to improve the anaerobic digestion process. Researchers have found that addition of conductive materials and/or electrically active cathodes to anaerobic digesters can stimulate the digestion process and increase methane content of biogas. It is hoped that optimization of anaerobic digesters will make biogas more readily accessible to the average person.

Insights in Waste Management Bioprocesses Using Genomic Tools.

Microbial capacities drive waste stabilization and resource recovery in environmental friendly processes. Depending on the composition of waste, a stress-mediated selection process ensures a scenario that generates a specific enrichment of microbial community. These communities dynamically change over a period of time while keeping the performance through the required utilization capacities. Depending on the environmental conditions, these communities select the appropriate partners so as to maintain the desired functional capacities. However, the complexities of these organizations are difficult to study. Individual member ratios and sharing of genetic intelligence collectively decide the enrichment and survival of these communities. The next-generation sequencing options with the depth of structure and function analysis have emerged as a tool that could provide the finer details of the underlying bioprocesses associated and shared in environmental niches. These tools can help in identification of the key biochemical events and monitoring of expression of associated phenotypes that will support the operation and maintenance of waste management systems. In this chapter, we link genomic tools with process optimization and/or management, which could be applied for decision making and/or upscaling. This review describes both, the aerobic and anaerobic, options of waste utilization process with the microbial community functioning as flocs, granules, or biofilms. There are a number of challenges involved in harnessing the microbial community intelligence with associated functional plasticity for efficient extension of microbial capacities for resource recycling and waste management. Mismanaged wastes could lead to undesired genotypes such as antibiotic/multidrug-resistant microbes.

Inactivation of Clostridium difficile in sewage sludge by anaerobic thermophilic digestion.

There has been an increase in community-associated Clostridium difficile infections with biosolids derived from wastewater treatment being identified as one potential source. The current study evaluated the efficacy of thermophilic digestion in decreasing levels of C. difficile ribotype 078 associated with sewage sludge. Five isolates of C. difficile 078 were introduced (final density of 5 log CFU/g) into digested sludge and subjected to anaerobic digestion at mesophilic (36 or 42 °C) or thermophilic (55 °C) temperatures for up to 60 days. It was found that mesophilic digestion at 36 °C did not result in a significant reduction in C. difficile spore levels. In contrast, thermophilic sludge digestion reduced endospore levels at a rate of 0.19-2.68 log CFU/day, depending on the strain tested. The mechanism of lethality was indirect - by stimulating germination then inactivating the resultant vegetative cells. Acidification of sludge by adding acetic acid (6 g/L) inhibited the germination of spores regardless of the sludge digestion temperature. In conclusion, thermophilic digestion can be applied to reduce C. difficile in biosolids, thereby reducing the environmental burden of the enteric pathogen.

Mixing characteristics of sludge simulant in a model anaerobic digester.

This study aims to investigate the mixing characteristics of a transparent sludge simulant in a mechanically agitated model digester using flow visualisation technique. Video images of the flow patterns were obtained by recording the progress of an acid-base reaction and analysed to determine the active and inactive volumes as a function of time. The doughnut-shaped inactive region formed above and below the impeller in low concentration simulant decreases in size with time and disappears finally. The 'cavern' shaped active mixing region formed around the impeller in simulant solutions with higher concentrations increases with increasing agitation time and reaches a steady state equilibrium size, which is a function of specific power input. These results indicate that the active volume is jointly determined by simulant rheology and specific power input. A mathematical correlation is proposed to estimate the active volume as a function of simulant concentration in terms of yield Reynolds number.

Isolation and Characterization of a New Methanobacterium formicicum KOR-1 from an Anaerobic Digester Using Pig Slurry.

A new methanogen was isolated from an anaerobic digester using pig slurry in South Korea. Only one strain, designated KOR-1, was characterized in detail. Cells of KOR-1 were straight or crooked rods, non-motile, 5 to 15 µm long and 0.7 µm wide. They stained Gram-positive and produced methane from H2+CO2 and formate. Strain KOR-1 grew optimally at 38°C. The optimum pH for growth was 7.0. The strain grew at 0.5% to 3.0% NaCl, with optimum growth at 2.5% NaCl. The G+C content of genomic DNA of strain KOR-1 was 41 mol%. The strain tolerated ampicillin, penicillin G, kanamycin and streptomycin but tetracycline inhibited cell growth. A large fragment of the 16S rRNA gene (~1,350 bp) was obtained from the isolate and sequenced. Comparison of 16S rRNA genes revealed that strain KOR-1 is related to Methanobacterium formicicum (98%, sequence similarity), Methanobacterium bryantii (95%) and Methanobacterium ivanovii (93%). Phylogenetic analysis of the deduced mcrA gene sequences confirmed the closest relative as based on mcrA gene sequence analysis was Methanobacterium formicicum strain (97% nucleic acid sequence identity). On the basis of physiological and phylogenetic characteristics, strain KOR-1 is proposed as a new strain within the genus Methanobacterium, Methanobacterium formicicum KOR-1.

Identification and quantification of microbial populations in activated sludge and anaerobic digestion processes.

Eight different phenotypes were studied in an activated sludge process (AeR) and anaerobic digester (AnD) in a full-scale wastewater treatment plant by means of fluorescent in situ hybridization (FISH) and automated FISH quantification software. The phenotypes were ammonia-oxidizing bacteria, nitrite-oxidizing bacteria, denitrifying bacteria, phosphate-accumulating organisms (PAO), glycogen-accumulating organisms (GAO), sulphate-reducing bacteria (SRB), methanotrophic bacteria and methanogenic archaea. Some findings were unexpected: (a) Presence of PAO, GAO and denitrifiers in the AeR possibly due to unexpected environmental conditions caused by oxygen deficiencies or its ability to survive aerobically; (b) presence of SRB in the AeR due to high sulphate content of wastewater intake and possibly also due to digested sludge being recycled back into the primary clarifier; (c) presence of methanogenic archaea in the AeR, which can be explained by the recirculation of digested sludge and its ability to survive periods of high oxygen levels; (d) presence of denitrifying bacteria in the AnD which cannot be fully explained because the nitrate level in the AnD was not measured. However, other authors reported the existence of denitrifiers in environments where nitrate or oxygen was not present suggesting that denitrifiers can survive in nitrate-free anaerobic environments by carrying out low-level fermentation; (e) the results of this paper are relevant because of the focus on the identification of nearly all the significant bacterial and archaeal groups of microorganisms with a known phenotype involved in the biological wastewater treatment.

Fate of Clostridium difficile during wastewater treatment and incidence in Southern Ontario watersheds.

AIMS: To investigate the prevalence of Clostridium difficile encountered during sewage treatment and in water sources into which treated effluent was directly or indirectly discharged. METHODS AND RESULTS: Samples from wastewater treatment plants (WWTPs) and rivers were collected and then enriched for Cl. difficile. Each of the isolates was subjected to toxinotyping and DNA typing using ribotyping, in addition to pulse-field gel electrophoresis. Cl. difficile was isolated from 92% (108/117) of the raw sludge and 96% (106/110) of the anaerobic digested sludge samples from two Ontario WWTPs. The pathogen was recovered from 73% (43/59) of dewatered biosolids and effluent discharge, in addition to river sediments 39% (25/64). Ribotype 078 (commonly associated with Community Acquired infections) was recovered from raw sewage (19%; 21/108), digested sludge (8%; 8/106), biosolids (35%; 15/43) and river sediments (60%; 15/25). CONCLUSIONS: Clostridium difficile is commonly encountered in raw sewage and survives the wastewater treatment process. The pathogen can then be disseminated into the wider environment via effluent and land application of biosolids. SIGNIFICANCE AND IMPACT OF THE STUDY: The study has illustrated the wide distribution of toxigenic Cl. difficile in WWTPs and river sediments although the clinical significance still requires to be elucidated.

Metagenomes and metagenome-assembled genomes from a sequentially fed anaerobic digester treating solid organic municipal waste.

We present a data set of four metagenomes and 281 metagenome-assembled genomes describing the microbial community of a laboratory-scale high solids anaerobic digester. Our objective was to obtain information on the coding potential of the microbial community and draft genomes of the most abundant organisms in the digester.

Metagenomes and metagenome assembled genomes from anaerobic digesters at three Canadian pulp and paper mills.

We present a dataset of six metagenomes and 323 metagenome assembled genomes (MAGs) describing the microbial community of anaerobic digesters at three Canadian pulp and paper mills. Our objective was to assess the coding potential of the microbial community and obtain draft genomes of key organisms in the digesters.

Phylogenomic discernments into Anaerolineaceae thermal adaptations and the proposal of a candidate genus Mesolinea.

This study delves into the evolutionary history of Anaerolineaceae, a diverse bacterial family within the Chloroflexota phylum. Employing a multi-faceted approach, including phylogenetic analyses, genomic comparisons, and exploration of adaptive features, the research unveils novel insights into the family's taxonomy and evolutionary dynamics. The investigation employs metagenome-assembled genomes (MAGs), emphasizing their prevalence in anaerobic environments. Notably, a novel mesophilic lineage, tentatively named Mesolinea, emerges within Anaerolineaceae, showcasing a distinctive genomic profile and apparent adaptation to a mesophilic lifestyle. The comprehensive genomic analyses shed light on the family's complex evolutionary patterns, including the conservation of key operons in thermophiles, providing a foundation for understanding the diverse ecological roles and adaptive strategies of Anaerolineaceae members.

Investigating the viral ecology and contribution to the microbial ecology in full-scale mesophilic anaerobic digesters.

In an attempt to assess the diversity of viruses and their potential to modulate the metabolism of functional microorganisms in anaerobic digesters, we collected digestate from three mesophilic anaerobic digesters in full-scale wastewater treatment plants treating real municipal wastewater. The reads were analyzed using bioinformatics algorithms to elucidate viral diversity, identify their potential role in modulating the metabolism of functional microorganisms, and provide essential genomic information for the potential use of virus-mediated treatment in controlling the anaerobic digester microbiome. We found that Siphoviridae was the dominant family in mesophilic anaerobic digesters, followed by Myoviridae and Podoviridae. Lysogeny was prevalent in mesophilic anaerobic digesters as the majority of metagenome-assembled genomes contained at least one viral genome within them. One virus within the genome of an acetoclastic methanogen (Methanothrix soehngenii) was observed with a gene (fwdE) acquired via lateral transfer from hydrogenotrophic methanogens. The virus-mediated acquisition of fwdE gene enables possibility of mixotrophic methanogenesis in Methanothrix soehngenii. This evidence highlighted that lysogeny provides fitness advantage to methanogens in anaerobic digesters by adding flexibility to changing substrates. Similarly, we found auxiliary metabolic genes, such as cellulase and alpha glucosidase, of bacterial origin responsible for sludge hydrolysis in viruses. Additionally, we discovered novel viral genomes and provided genomic information on viruses infecting acidogenic, acetogenic, and pathogenic bacteria that can potentially be used for virus-mediated treatment to deal with the souring problem in anaerobic digesters and remove pathogens from biosolids before land application. Collectively, our study provides a genome-level understanding of virome in conjunction with the microbiome in anaerobic digesters that can be used to optimize the anaerobic digestion process for efficient biogas generation.