Stability Of Anaerobic Digestion Research Articles

Biotic and abiotic factors acting on community assembly in parallel anaerobic digestion systems from a brewery wastewater treatment plant

ABSTRACT Anaerobic digestion is a complex microbial process that mediates the transformation of organic waste into biogas. The performance and stability of anaerobic digesters relies on the structure and function of the microbial community. In this study, we asked whether the deterministic effect of wastewater composition outweighs the effect of reactor configuration on the structure and dynamics of anaerobic digester archaeal and bacterial communities. Biotic and abiotic factors acting on microbial community assembly in two parallel anaerobic digestion systems, an upflow anaerobic sludge blanket digestor (UASB) and a closed digester tank with a solid recycling system (CDSR), from a brewery WWTP were analysed utilizing 16S rDNA and mcrA amplicon sequencing and genome-centric metagenomics. This study confirmed the deterministic effect of the wastewater composition on bacterial community structure, while the archaeal community composition resulted better explained by organic loading rate (ORL) and volatile free acids (VFA). According to the functions assigned to the differentially abundant metagenome-assembled genomes (MAGs) between reactors, CDSR was enriched in genes related to methanol and methylamines methanogenesis, protein degradation, and sulphate and alcohol utilization. Conversely, the UASB reactor was enriched in genes associated with carbohydrate and lipid degradation, as well as amino acid, fatty acid, and propionate fermentation. By comparing interactions derived from the co-occurrence network with predicted metabolic interactions of the prokaryotic communities in both anaerobic digesters, we conclude that the overall community structure is mainly determined by habitat filtering.

Functional Redundant Microbiome Enhanced Anaerobic Digestion Efficiency under Ammonium Inhibition Conditions.

Revealing the role of functional redundancy is of great importance considering its key role in maintaining the stability of microbial ecosystems in response to various disturbances. However, experimental evidence on this point is still lacking due to the difficulty in "manipulating" and depicting the degree of redundancy. In this study, manipulative experiments of functional redundancy were conducted by adopting the mixed inoculation strategy to evaluate its role in engineered anaerobic digestion systems under ammonium inhibition conditions. The results indicated that the functional redundancy gradient was successfully constructed and confirmed by evidence from pathway levels. All mixed inoculation groups exhibited higher methane production regardless of the ammonium level, indicating that functional redundancy is crucial in maintaining the system's efficiency. Further analysis of the metagenome-assembled genomes within different functional guilds revealed that the extent of redundancy decreased along the direction of the anaerobic digestion flow, and the role of functional redundancy appeared to be related to the stress level. The study also found that microbial diversity of key functional populations might play a more important role than their abundance on the system's performance under stress. The findings provide direct evidence and highlight the critical role of functional redundancy in enhancing the efficiency and stability of anaerobic digestion.

Bioaugmentation strategies based on bacterial and methanogenic cultures to relieve stress in anaerobic digestion of protein-rich substrates

Anaerobic co-digestion of protein-rich substrates is a prominent strategy for converting valuable feedstocks into methane, but it releases ammonia, which can inhibit the overall process. This study developed a cutting-edge combined culturomic and metagenomic approach to investigate the microbial composition of an ammonia-tolerant biogas plant. Newly-isolated microorganisms were used for bioaugmentation of stressed batch reactors fed with casein, maize silage and their combination. A co-culture enriched with proteolytic bacteria was isolated, selected and compared with the proteolytic collection strain Pseudomonas lundensis DSM6252. The co-culture and P. lundensis were combined with the ammonia-resistant archaeon Methanoculleus bourgensis MS2 to boost process stability. A microbial population pre-adapted to casein was also tested for evaluating the digestion of protein-rich feedstock. The promising results suggest combining proteolytic bacteria and M. bourgensis could exploit microbial co-cultures to improve anaerobic digestion stability and ensure stable productivity even under the harshest of ammonia conditions.

Metaproteomics analysis of anaerobic digestion of food waste by the addition of calcium peroxide and magnetite.

Adding trace calcium peroxide and magnetite into a semi-continuous digester is a new method to effectively improve the anaerobic digestion of food waste. However, the microbial mechanism in this system has not been fully explored. Metaproteomics further revealed that the most active and significantly regulated genus u_p_Chloroflexi had formed a good cooperative relationship with Methanomicrobiales and Methanothrix in the system. u_p_Chloroflexi decomposed more organic compounds into CO2, acetate, amino acids, and other substances by alternating between short aerobic-anaerobic respiration. It perceived and adapted to the surrounding environment by producing biofilm, extracellular enzymes, and accelerating substrate transport, formed a respiratory barrier, and enhanced iron transport capacity by using highly expressed cytochrome C. The methanogens formed reactive oxygen species scavengers and reduced iron transport to prevent oxidative damage. This study provides new insight for improving the efficiency of anaerobic digestion of food waste and identifying key microorganisms and their regulated functional proteins in the calcium peroxide-magnetite digestion system.IMPORTANCEPrevious study has found that the combination of calcium peroxide and magnetite has a good promoting effect on the anaerobic digestion process of food waste. Through multiple omics approaches, information such as microbial population structure and changes in metabolites can be further analyzed. This study can help researchers gain a deeper understanding of the digestion pathway of food waste under the combined action of calcium peroxide and magnetite, further elucidate the impact mechanisms of calcium peroxide and magnetite at the microbial level, and provide theoretical guidance to improve the efficiency and stability of anaerobic digestion of food waste, as well as reduce operational costs. This research contributes to improving energy recovery efficiency, promoting sustainable management and development of food waste, and is of great significance to environmental protection.

A Case Study on Small- and Centralized Biogas Plants and Energy Production Capacities in South Gyeongsang Province

Objectives : The primary goals of this research were to assess the viability and practicality of small-scale village facilities as well as central commercial biogas plants. Additionally, the study aimed to create predictive models by exploring various codigestion scenarios.Methods : The study conducted a comprehensive analysis of available biomass and its maximum energy potential through anaerobic digestion in every city, county, and village within South Gyeongsang province. Five distinct codigestion scenarios were explored, encompassing assessments of processing capacity, energy production potential, and the necessary digester capacity for anaerobic digestion. At the village level, the scenarios comprised: C1, which involved sole digestion of manure; C2, codigestion of manure and food waste in a 7:3 ratio; C3, codigestion of pig slurry and slaughterhouse waste in a 9:1 ratio; C4, multiple codigestion with PS:FW:SW=6.5:2.8:0.8; and finally, C5, involving the addition of sewage and sewage sludge to the codigestion process of C4's biomass.Results and Discussion : The biomass generated in South Gyeongsang province was 9430 tons/day, with a methane production potential of 167 million cubic meters/year. This biomass had an energy production potential of 156,000 TOE/year and a potential electricity generation of 732.7 GW/year, based on the annual petroleum conversion ton. Codigestion (C5) enabled up to 720% more electricity generation compared to sole digestion of manure (C1). Mixing pig slurry and food waste in a 7:3 ratio resulted in approximately 18% more electricity production compared to the case where manure was mixed with slaughterhouse by-products in a 9:1 ratio.Conclusion : Biomass imbalance was significant in most regions, particularly due to high variations in food waste generation between regions. Obtaining alternative resources and integrating various biomass for anaerobic digestion, especially in rural areas, is crucial for achieving stable anaerobic digestion and high methane production. Regions with high biomass density are predicted to support large-scale biogas facilities following European standards, while 25 villages showed the potential for small-scale biogas facilities.

Biocatalyst enhanced biogas production from food and fruit waste through anaerobic digestion

In recent years, the world has faced the adverse effects of global warming and waste management issues. Food waste is one of the major constituents of solid waste. Currently, the world is in the throes of finding an alternative source of fossil fuels, which could lower the energy demand and bring about a pollution-free environment. The stability of anaerobic digestion is significantly influenced by trace elements (TE), which are micronutrients for microbes. Experimental measurements were made of the effects of trace metals (cobalt (Co), nickel (Ni), magnetite (Fe2+Fe3+2O4) and biochar) on mesophilic and thermophilic anaerobic digestion of food waste. The study's major significance is identifying the potential catalyst for the anaerobic digestion system and achieving the best production efficiency. Adding micronutrients increased biogas generation, but it was hampered by the excessive addition of trace metalsthe excessive addition of trace metals hampered it. More biogas was produced when Co was added. We have achieved 42% of methane production with 28 days of hydraulic retention time. The findings can provide quantitative data on the replenishment of trace metals for efficient anaerobic digestion. This work presents novel information about the trace elements and their enhancement inside the biodigester for kitchen and fruit wastes.

New insights into antibiotic stimulation of methane production during anaerobic digestion

Residual antibiotics in swine wastewater pose a critical challenge for stable anaerobic digestion (AD). This study offers fresh insights into the anaerobic treatment of swine wastewater. The results showed that the presence of three typical antibiotics (sulfamethoxazole (SMX), oxytetracycline (OTC) and ciprofloxacin (CIP)) in swine wastewater could promote methane production by stimulating the production and conversion of ethanol. Among them, SMX exhibited the strongest methane promotion effect, with the cumulative methane production increasing from 138.47 to 2204.19 mL/g VS. According to the microbial community structure, antibiotics could promote the growth of Corynebacterium, Lutispora and hydrogenotrophic methanogens (Methanosassiliicoccus, Methanobrevibacter, and Methanobacterium), but inhibit the enrichment of acetoclastic methanogen (Methanosaeta). The relative abundance of Methanosaeta decreased from 2.93–19.80% to 0.52–2.58% under antibiotic stress. Furthermore, there were significant differences in the influence of different antibiotic types on methanogenic pathways. Specifically, OTC and CIP promoted the acetoclastic and hydrogenotrophic pathways, respectively, to enhance methane production. However, SMX could promote both acetoclastic and hydrogenotrophic pathways.

Unraveling Anaerobic Digestion Instability: A Simple Index Based on the Kinetic Balance of Biochemical Reactions

Restoration potential (RP) and deterioration potential (DP) were formulated to shed light on the kinetic balance between anaerobic biochemical reactions. RP is gauged by the ratio of the methanogenesis rate (MR) to the acidogenesis rate (AR), while the DP is the sum of the accumulation rate (AcR) and dilution rate (DR) of total VFAs, normalized using the AR. In an anaerobic digester for a mixture of pulverized food waste and liquified sewage sludge, an RP above 1.0 signifies a restorative state in the kinetic balance of anaerobic biochemical reactions across various operational phases, including startup and steady state, and shifts in organic loading rate. Conversely, a DP value of 0.0 or higher denotes a deterioration in the kinetic balance. The instability index (ISI), calculated as the DP to RP ratio, serves as an indicator of an anaerobic digestion state. When the standard deviation of ISI surpasses 0.2, it signifies instability in biochemical reactions; however, an average ISI below 0.05 indicates a stable digestion process. The study underscores the efficacy of RP, DP, and ISI as robust indicators for assessing the stability of anaerobic digestion based on the kinetics of biochemical reactions.

Iron and Nickel Supplementation Exerts a Significant Positive Effect on the Hydrogen and Methane Production from Organic Solid Waste in a Two-Stage Digestion

Two-stage anaerobic digestion and trace metals (TM) supplementation are promising techniques to improve biogas production. Fe2+ and Ni2+ can improve process stability since they are part of the cofactors of enzymes and microorganisms’ growth. This work attempted to evaluate the effect of Fe2+ and Ni2+ addition on H2-rich biogas production from organic solid waste and the CH4-rich biogas production from the acidogenic effluents (AEs) enriched with TM. The TM concentrations that enhanced the hydrogen yield in the batch were 0.25 mg/L of Ni2+ and 334 mg/L of Fe2+. These concentrations were evaluated in a two-stage system. The substrate for the batch tests and fermentative reactor (first stage) was OSW. The AE generated in the first stage was the substrate to produce CH4-rich biogas in the second stage. In the first stage, the productivity achieved was 1823 ± 160 mL H2/L/day. However, TM supplementation decreased productivity by 65% since the VS removal increased. Megasphaera genus predominated in the first stage. Regarding the methanogenic reactor, the undiluted AE without TM caused the fast decay of the process. Nevertheless, the reactor operated stably after using AE enriched with TM as a substrate, and CH4 yields increased by 42%. The highest productivity achieved in the second stage was 1278 ± 42 mL CH4/L/day, operating with an organic loading rate of 2.8 gVS/L/day. The genera Proteiniphilum, Thermovirga, DMER64, Anaerovorax, and Syntrophomonas predominated in the second stage. In conclusion, AE enriched with TM can be used to recover the stability of anaerobic digesters, increasing methane production.

The impact of semi-continuous and alternating microbial feeding patterns on methane yield from UASB reactors

Feeding strategy represents one of the most important bioreactor operation parameters, however, how different feeding patterns impact reactor microbiome development and treatment performance in up-flow anaerobic sludge blanket (UASB) reactors has not been systematically investigated. In the present study, three feeding strategies, including continuous feeding, semi-continuous feeding (with starvation-feast cycles), and alternate feeding (with high loading-low loading cycles) were assessed and compared using three laboratory-scale UASB reactors. It was observed that both long and short starvation-feast cycles provided by a semi-continuous feeding strategy failed to sustain stable anaerobic digestion under the conditions examined in the present study, while alternate feeding with high and low loading cycles supported microbial development. This feeding pattern resulted in an average methane yield of 74 ± 8.5% and an effluent COD removal efficiency of 89 ± 2.8%, which is comparable to the reactor operated under a continuous feeding pattern (Methane yield of 72 ± 2.4% and a COD removal efficiency of 87 ± 7.7%). Interestingly, as compared to continuous operation, reactors experienced starvation/feast stress (i.e., semi-continuous feeding) developed significantly higher methanogenic activities once continuous feeding was presumed, with dominant methanogens shifted from Methanosaeta in continuous feeding UASB to Methanosarcina in reactors undergone semi-continuous feeding. It was concluded that reactor feeding strategies can significantly impact microbiome communities in UASB, and an alternate feeding pattern is preferred, as compared to semi-continuous operation when reactor feeding cannot be continuously supplied.

The influence of biochar supported nano‐zero valent iron on the anaerobic digestion of sulfate wastewater

AbstractIn this study, the effect of biochar supported nano‐zero valent iron (nZVI/BC) on anaerobic digestion of sulfate wastewater including methane yield, total volatile fatty acids, COD balance, sulfur balance, variation of iron (Fe2+) and microbial community structure was investigated by a batch‐scale experiment. The results showed that nZVI/BC could effectively maintain the stability of anaerobic digestion even at a high sulfate concentration. At SO42−/COD = 0.1 with 2 g nZVI/BC, the maximum methane yield (Bmax) and maximum methane production rate (Rmax) were obtained with a value of 3940.6648 mL and 553.6266 mL/day, respectively. When the SO42−/COD ratio was increased from 0.1 to 2, the ratio of COD converting to CH4 was decreased from 80.85% to 20.16%, while the ratio of COD used for SO42− reduction was increased from 8.79% to 77.96%. Meanwhile, nZVI/BC could enrich the hydrogentrophic Methanobacterium especially Methanobacterium with an average relative abundance of 75.86%.

Emerging Strategies for Enhancing Propionate Conversion in Anaerobic Digestion: A Review.

Anaerobic digestion (AD) is a triple-benefit biotechnology for organic waste treatment, renewable production, and carbon emission reduction. In the process of anaerobic digestion, pH, temperature, organic load, ammonia nitrogen, VFAs, and other factors affect fermentation efficiency and stability. The balance between the generation and consumption of volatile fatty acids (VFAs) in the anaerobic digestion process is the key to stable AD operation. However, the accumulation of VFAs frequently occurs, especially propionate, because its oxidation has the highest Gibbs free energy when compared to other VFAs. In order to solve this problem, some strategies, including buffering addition, suspension of feeding, decreased organic loading rate, and so on, have been proposed. Emerging methods, such as bioaugmentation, supplementary trace elements, the addition of electronic receptors, conductive materials, and the degasification of dissolved hydrogen, have been recently researched, presenting promising results. But the efficacy of these methods still requires further studies and tests regarding full-scale application. The main objective of this paper is to provide a comprehensive review of the mechanisms of propionate generation, the metabolic pathways and the influencing factors during the AD process, and the recent literature regarding the experimental research related to the efficacy of various strategies for enhancing propionate biodegradation. In addition, the issues that must be addressed in the future and the focus of future research are identified, and the potential directions for future development are predicted.

Simultaneous addition of CO2-nanobubble water and iron nanoparticles to enhance methane production from anaerobic digestion of corn straw

In this research, CO2-nanobubble water (CO2-NBW) and iron nanoparticles (Fe0NPs) were added simultaneously to exploit individual advantages to enhance the methanogenesis process from both the stability of anaerobic digestion (AD) system and the activity of anaerobic microorganism aspects. Results showed that the AD performance was enhanced by supplementing with CO2-NBW or Fe0NPs individually, and could be further improved by simultaneous addition of the two additives. The maximum methane yield was achieved in the CO2-NBW + Fe0NPs reactor (141.99 mL/g-VSadded), which increased by 26.16% compared to the control group. Similarly, the activities of the electron transfer system (ETS) and enzyme were improved. The results of microbial community structure revealed that the addition of CO2-NBW and Fe0NPs could improve the abundance of dominant bacteria (Anaerolineaceae, Bacteroidales, and Prolixibacteraceae) and archaea (Methanotrichaceae and Methanospirillaceae). Additionally, the functional metabolic prediction heatmap indicated that metabolic functional genes favorable for AD of corn straw were enhanced.

The Impact of Sewage Sludge-Sweet Sorghum Blends on the Biogas Production for Energy Purposes

The paper presents research on the impact of adding various forms of sorghum to sewage sludge on the anaerobic digestion process. The use of liquid sewage sludge alone in biogas plants at wastewater treatment plants is inefficient due to the low total solid (dry matter) content of this substrate. The tests revealed that the production of methane in biogas is low and amounted to 17.9% (105.4 Nm3∙Mg−1, VS—volatile solid). Therefore, other substrates should be blended with sewage sludge to increase the total solid of the batch. Sorghum silage, sorghum pomace, and sorghum juice were added to the sewage sludge in various proportions during the research. As a result, the improvement of the biogas process, the stabilization of the biogas production curve, as well as the increase in methane yield were observed. The most biogas and methane were obtained from a mixture of sorghum juice (5%) and sewage sludge (664.8 Nm3∙Mg−1 VS and 53.9%, respectively). Biogas production from other substrates based on sorghum and sewage sludge ranged from 457.4 to 588.8 Nm3∙Mg−1 VS. For a mixture of juice (7%) and sewage sludge, the batch was acidified, and biogas production was only 281.5 Nm3∙Mg−1 VS. Studies have shown that intelligent blending of an alternative raw material (compared to traditional maize silage) with sewage sludge allows for similar biogas yields while maintaining a stable anaerobic digestion process.

Biogas Production from Residues of Industrial Insect Protein Production from Black Soldier Fly Larvae Hermetia illucens (L.): An Evaluation of Different Insect Frass Samples

Insect biomass shows promise as an alternative animal feedstuff with a low climate effect. Industrial insect rearing generates residual materials, such as feed remains and insect excrements, so-called insect frass, which exhibits a high organic content. Commonly, these residues are utilized as soil amendment. Information on the suitability of these residues for biogas production is rather scarce. The energetic utilization of insect frass as feedstock for anaerobic digestion (AD) would allow for the simultaneous residue material reduction and bioenergy production. Additionally, synergies in heat management could arise using the exhaust heat of the biogas plant in the insect farming process. In laboratory-scale anaerobic digestion trials, the specific methane yield (SMY) of six different insect frass samples from black soldier fly (Hermetia) rearing were tested in batch biochemical methane potential (BMP) tests. Further, semi continuous anaerobic digestion trials on a lab scale using continuously stirred tank reactors (CSTRs) were carried out with Hermetia insect frass from a pilot plant operation in order to determine the digestibility and process stability of the AD process. The BMP results showed SMY values of the different insect frass samples ranging from 201 ± 9 to 287 ± 37 mL/gVS that are similar to those of other animal excrements, such as cow or pig manure already been used as feedstock in agricultural biogas plants. Results of the semi-continuous digestion of insect frass from the pilot plant operation showed a SMY value of 167 ± 15 mL/gVS, suggesting no process-inhibiting effect caused by the feed material. Although, the high nitrogen content must be taken into account for stable AD performance.

Study on the stability of anaerobic digestion of food waste and the waste mushroom substrate based on SBR reactor and Netlogo simulation

Study on the stability of anaerobic digestion of food waste and the waste mushroom substrate based on SBR reactor and Netlogo simulation

The role of microbial ecology in improving the performance of anaerobic digestion of sewage sludge.

The use of next-generation diagnostic tools to optimise the anaerobic digestion of municipal sewage sludge has the potential to increase renewable natural gas recovery, improve the reuse of biosolid fertilisers and help operators expand circular economies globally. This review aims to provide perspectives on the role of microbial ecology in improving digester performance in wastewater treatment plants, highlighting that a systems biology approach is fundamental for monitoring mesophilic anaerobic sewage sludge in continuously stirred reactor tanks. We further highlight the potential applications arising from investigations into sludge ecology. The principal limitation for improvements in methane recoveries or in process stability of anaerobic digestion, especially after pre-treatment or during co-digestion, are ecological knowledge gaps related to the front-end metabolism (hydrolysis and fermentation). Operational problems such as stable biological foaming are a key problem, for which ecological markers are a suitable approach. However, no biomarkers exist yet to assist in monitoring and management of clade-specific foaming potentials along with other risks, such as pollutants and pathogens. Fundamental ecological principles apply to anaerobic digestion, which presents opportunities to predict and manipulate reactor functions. The path ahead for mapping ecological markers on process endpoints and risk factors of anaerobic digestion will involve numerical ecology, an expanding field that employs metrics derived from alpha, beta, phylogenetic, taxonomic, and functional diversity, as well as from phenotypes or life strategies derived from genetic potentials. In contrast to addressing operational issues (as noted above), which are effectively addressed by whole population or individual biomarkers, broad improvement and optimisation of function will require enhancement of hydrolysis and acidogenic processes. This will require a discovery-based approach, which will involve integrative research involving the proteome and metabolome. This will utilise, but overcome current limitations of DNA-centric approaches, and likely have broad application outside the specific field of anaerobic digestion.

Maintaining the Long-Term Stability of Anaerobic Digestion of Maize Straw in a Continuous Plug Flow Reactor by Verifying the Key Role of Trace Elements

A mesophilic anaerobic digestion reactor fed with maize straw was investigated in a plug flow reactor for 150 days. The process performance was evaluated through the stable, unstable, and recovery stages. Results obtained in this study showed that the reactor maintained stable within approximately two months, but the gradual depletion of trace elements (Fe, Co and Ni) and significant accumulation of volatile fatty acids (8.07 g/L) occurred in the reactor by the 120th day. Pig manure containing higher trace elements, therefore, was mixed with maize straw at a ratio of 1:4 on a dry matter basis to feed the reactor. As a result of the consequent reactor recovery, volatile fatty acids decreased significantly, and biogas production increased. During the subsequent stable operation stage, a methane yield of 0.21 L/g-VSadded was obtained and methane content stabilized at 54%. Additionally, the uptake of the elements was determined quantitatively, highlighting the necessity of mixing maize straw with pig manure. Therefore, it is imperative to co-digest maize straw with trace element-rich substrates or supply trace elements to ensure the long-term stability of the anaerobic digestion process.Graphical Abstract

Central Composite Design Optimisation of Banana Peels/Magnetite for Anaerobic Biogas Production from Wastewater

Biogas production from wastewater as a function to curb waste and provide energy security has gained worldwide attention. Ensuring the stability of anaerobic digestion (AD) of physiochemical and biological complexity necessitates optimization. In this study, a central composite design (CCD) from a response surface methodology (RSM) was employed to evaluate and optimize the effects of bio-stimulation of banana peels coupled with magnetite on the anaerobic digestion of wastewater to produce biogas. An experimental matrix of 14 runs using the CCD, with two factors (nanoparticle and biochar load) as a function of pH, biogas production, and COD removal by the AD process was operated at a constant mesophilic temperature (37 °C) for 28 days. The analysis of variance (ANOVA) showed that the quadratic models attained were significant (p-values < 0.05) with a high coefficient of determination (R2) values closer to 1. The optimized conditions, including nanoparticle (0.46 g) and biochar (0.66 mgVS/L), resulted in biogas production (19.26 mL/day), pH (7.07), and COD removal (75.17%). This suggests 100% desirability at a 95% confidence level. This finding depicts the trade-off between biogas productivity, biodegradability, and stability of the AD process established for future consideration of using nanoparticles as bio-stimulant.

The Effect of Operating Strategies on the Anaerobic Digestion of Gentamicin Mycelial Residues: Insights into the Enhancement of Methane Production and Attenuation of Gentamicin Resistance.

Anaerobic digestion (AD) has been widely employed for converting various biowastes into renewable energy. However, AD of gentamicin mycelial residues (GMRs, a byproduct of gentamicin production) is limited by ammonia inhibition and antimicrobial resistance risk. Compared to mesophilic AD (MMAD) of GMRs, this study looked into three semicontinuous AD processes, i.e., codigestion with wheat straw, thermophilic digestion (TAcoD), and AD at shortened retention time (RT). Results showed that a stable and safe AD could be achieved under suitable operating conditions. Co-digestion could effectively mitigate the adverse effect of ammonia inhibition. The methane production increased by 35.86% in TAcoD compared to that in MMAD and 43.99% of hazardous waste was reduced in TAcoD. Concerning the antimicrobial resistance of AD system, gentamicin was degraded efficiently and the degradation process was not involved in the expression of antibiotic resistance genes (ARGs) related to modifying enzyme. Effective removal of ARGs under three operating strategies was associated with a higher reduction in bacterial abundance of potential hosts. In addition, the changes in the relevant proteins for transformation and conjugation as predicted by PICRUSt suggested that thermophilic condition and shorter RT were conducive to the reduction of the dissemination risks of ARGs.