Search Results (149)

While the Ankom RF system facilitates efficient high-throughput in vitro fermentation studies, its high cost and limited flexibility constrain its broader applicability. To address these limitations, we developed and validated a low-cost, modular gas monitoring system (FerME), assembled from commercially available components. To evaluate its performance and reproducibility relative to the Ankom RF system (Ankom Technology, Macedon, NY, USA), in vitro rumen fermentation experiments were conducted under strictly controlled and identical conditions. Whole rumen contents were collected approximately 2 h post-feeding from individual mid- or late-lactation dairy cows and immediately transported to the laboratory. Each fermenter received 50 mL of processed rumen fluid, 100 mL of anaerobically prepared artificial saliva buffer, and 1.2 g of the donor cow’s diet. Bottles were sealed with the respective system’s pressure sensors, flushed with CO₂, and incubated in a 50 L water bath maintained at 39 °C. FerME (New Taipei City, Taiwan) and Ankom RF fermenters were placed side-by-side to ensure uniform thermal conditions. To assess the effect of filter bag use, an additional trial employed Ankom F57 filter bags (Ankom Technology, Macedon, NY, USA; 25 μm pore size). Trial 1 revealed no significant differences in cumulative gas production, volatile fatty acids (VFAs), NH₃-N, or pH between systems (p > 0.05). However, the use of filter bags reduced gas output and increased propionate concentrations (p < 0.05). Trial 2, which employed filter bags in both systems, confirmed comparable results, with the FerME system demonstrating improved precision (CV: 4.8% vs. 13.2%). Gas composition (CH₄ + CO₂: 76–82%) and fermentation parameters remained consistent across systems (p > 0.05). Importantly, with 12 pressure sensors, the total cost of FerME was about half that of the Ankom RF system. Collectively, these findings demonstrate that FerME is a reliable, low-cost alternative for real-time rumen fermentation monitoring and could be suitable for studies in animal nutrition, methane mitigation, and related applications. Full article

In this study, the effects of graphene-based nanomaterials—specifically graphene nanoplatelets (GNPs) and graphene oxide (GO) nanosheets—on methane (CH₄) production during anaerobic digestion (AD) of thermally hydrolyzed sewage sludge were investigated. Anaerobic digestion was carried out over a 40-day period under mesophilic conditions in batch digesters with a volume of 2.65 L. The influence of various dosages of GNPs and GO nanosheets on methane yields was assessed, including a comparison between GNPs with different specific surface areas (320 m²/g and 530 m²/g). The highest CH₄ yield (194 mL/g-VS_added) was observed with a GNP dosage of 5 mg/g-TS and a surface area of 530 m²/g, showing an increase of 3.08% compared to the control. This treatment group had the greatest positive effect also on the degradation of organic matter, with total solids (TS) and volatile solids (VS) removal reaching 34.35% and 44.18%, respectively. However, the GO dosages that significantly decreased cumulative CH₄ production were determined to be 10–15 mg/g-TS. Graphene oxide at dosages of 10 and 15 mg/g-TS reduced specific cumulative CH₄ yields by 4.03% and 5.85%, respectively, compared to the control, indicating CH₄ yield inhibition. This lab-scale study highlights the potential for integrating GNPs into full-scale, continuously operated wastewater treatment anaerobic digesters for long-term use in future applications. Full article

The urbanization-driven surge in kitchen waste necessitates optimized dry anaerobic digestion (DAD; total solids > 15%). Despite its valorization potential, this technology requires efficiency improvements due to mass transfer constraints. This study evaluated TS effects (15%, 20%, or 25%) on methane production. The TS = 20% system achieved peak cumulative methane yield (405.73 ± 11.71 mL/gVS), exceeding TS = 15% (348.09 ± 12.19 mL/gVS) and TS = 25% (293.08 ± 3.55 mL/gVS). This optimization was attributable to synergistic maintenance of metabolic equilibrium through autonomous pH recovery, rapid VFAs degradation, and enhanced TAN tolerance. Conversely, TS = 25% exhibited impaired mass transfer efficiency under high solids, causing VFAs accumulation, ammonia toxicity, and progressive pH decline to 7.5, indicating system destabilization. Organic degradation analysis confirmed superior conversion efficiency in TS = 20% through dynamic SPS–SPN equilibrium. Microbial analysis revealed enhanced metabolic efficiency via synergistic interactions between acetoclastic and hydrogenotrophic methanogens in TS = 20%. This research provides technical parameters for optimizing methane production in kitchen waste DAD systems. Full article

Despite being recognized as toxic in anaerobic systems, sulfide’s potential to enhance hydrogen fermentation via microbial modulation remains underexplored. This study evaluated the combined effects of sulfide concentration (0–800 mg S/L) and heat pretreatment on hydrogen production during dark fermentation (DF). Without pretreatment, hydrogen yield reached 83 ± 2 mL/g COD at 0 mg S/L but declined with increasing sulfide, becoming negligible at 800 mg S/L. In contrast, heat-pretreated inocula showed markedly improved performance: peak cumulative production (4628 ± 17 mL) and yield (231 ± 1 mL/g COD) were attained at 200 mg S/L, while the maximum production rate (1462 ± 64 mL/h) occurred at 400 mg S/L. These enhancements coincided with elevated acetic and butyric acids, indicating a metabolic shift toward hydrogen-producing pathways. The microbial analysis of heat-pretreated samples revealed an enrichment of Clostridium butyricum (from 73.1% to 87.5%) and Clostridium perfringens, which peaked at 13.5% at 400 mg S/L. This species contributed to butyric acid synthesis. At 800 mg S/L, Clostridium perfringens declined sharply to 0.6%, while non-hydrogenogenic Levilinea saccharolytica proliferated, correlating with reduced butyric acid and hydrogen output. These findings indicate that sulfide supplementation, when combined with heat pretreatment, selectively restructures microbial communities and metabolic pathways, enhancing DF performance. Full article

This study evaluated the viability of using the solid residues (bagasse) of the mezcal industry produced with Agave durangensis as a substrate for biogas production, using two chemical pretreatments, acid (HCl) and alkaline (KOH + Ca(OH)₂), to enhance its biodegradability and improve the anaerobic digestion (AD) process. The chemical composition of bagasse was analyzed before and after the chemical pretreatments and then AD experiments were conducted in anaerobic sequential batch reactors (A-SBR) to analyze the effect of pretreatments on biogas production performance. The results showed that acid pretreatment increased cellulose content to 0.606 g, which represented an increase of 34%, and significantly reduced hemicellulose. In contrast, alkaline pretreatment did not show significant changes in cellulose composition, although it caused a swelling of the Agave durangensis mezcal bagasse (Ad-MB) fibers. In terms of biogas production, Ad-MB pretreated with acid (Ad-MB-acid) increased cumulative production by 76% compared to the Agave durangensis mezcal bagasse that was not pretreated (Ad-MB-not pretreated) and by 135% compared to Agave durangensis mezcal bagasse pretreated with an alkaline solution (Ad-MB-alkaline). These results confirmed that Agave durangensis solid waste from the mezcal industry that receives acidic chemical pretreatment has the potential to generate biogas as a sustainable biofuel that can be used to reduce the ecological footprint of this industry. Full article

Anaerobic digestion for biogas production represents a crucial approach to achieving the high-value utilization of agricultural solid waste. The adoption of multi-material co-digestion offers a viable solution to overcome the inherent constraints associated with single-substrate digestion, thereby significantly enhancing the efficiency of resource utilization. This study explored a co-digestion system using dairy manure and cucumber vines as substrates, uncovering how total solids (TS) influence the methane yield and microbial community characteristics. All treatments exhibited swift methane fermentation, with daily production initially increasing before declining. Cumulative methane production increased with the increasing TS contents. These results may be linked to pH value and the concentration of volatile fatty acids (VFAs). Except for the 6% TS treatment, digesters across different TS levels maintained a favorable final pH of 7.4–8.4, while VFA concentrations exhibited a downward trend as TS contents increased. The treatment with the highest TS concentration (25%) demonstrated superior performance, achieving the maximum volumetric methane yield. This yield was 1.6 to 9.1 times higher than those obtained at low (6–10%) and medium (12–18%) TS concentrations. Microbial community analysis revealed that during the peak methane production phase, Firmicutes and Methanoculleus were the predominant bacterial and archaeal phyla, respectively. The microbial community structure changed with different TS levels. This study offers valuable scientific insights for enhancing biogas production efficiency in co-digestion systems. Full article

This study investigates the optimization of enzymatic hydrolysis for enhancing carbohydrate release from microalgal biomass and its subsequent impact on methane production during anaerobic digestion. Using Response Surface Methodology with a Box–Behnken design comprising 15 experimental runs, the effects of enzyme loading (20–40 mg/gVS), pH (4.5–5.5), and incubation time (24–72 h) were evaluated. A quadratic regression model was developed to predict carbohydrate release, revealing significant interactions between these factors. The optimal conditions for enzymatic hydrolysis were determined to be a cellulase dose of 20 mg/gVS, pH 5.0, and an incubation period of 72 h. The model demonstrated excellent predictive accuracy, with an R² value of 0.9894 and an adjusted R² of 0.9704. Enzymatic hydrolysis significantly improved methane and biogas yields, with cumulative production reaching 52.50 mL/gVS and 95.62 mL/gVS, respectively, compared to 6.98 mL/gVS and 20.94 mL/gVS for untreated samples. The findings highlight the importance of optimizing enzyme loading and reaction time, while pH variations within the studied range had minimal impact. This study underscores the potential of enzymatic hydrolysis to enhance the bioavailability of organic matter, thereby improving the efficiency of anaerobic digestion for biogas production. Full article

Removal of micropollutants using biological treatment systems remains a challenge, since conventional bioprocess systems require adaptations to provide more advanced treatment. An ambient temperature upflow anaerobic sludge blanket (UASB) reactor was employed, followed by a two-stage (saturated and unsaturated) vertical subsurface flow (VSSF) constructed wetland (CW) system, to treat domestic wastewater from a nearby settlement and investigate the occurrence and fate of 10 contaminants of emerging concern (CECs) in decentralized, non-conventional treatment systems. The integrated UASB—two-stage CW system achieved high performance regarding abatement of target CECs across all periods. Removal efficiencies ranged from 78% ± 21% (ketoprofen) to practically 100% (2-hydroxybenzothiazole). The pilot system was found to be robust performance-wise and provided enhanced treatment in comparison to a conventional wastewater treatment plant operating in parallel. Most of the target CECs were successfully treated by UASB, saturated and unsaturated CWs, while ibuprofen, bisphenol A and diclofenac were mostly removed in the unsaturated CW. Environmental risk assessment revealed that triclosan poses a significant ecological risk to algae during treated wastewater disposal into the aquatic environment. Additionally, cumulative risk quotient indicated that the potential for mixture toxicity should be carefully considered across all trophic levels. Full article

Anaerobic digestion (AD) is a preferred method for food waste (FW) treatment due to its sustainability and potential for production of renewable bioenergy. However, the accumulation of volatile fatty acids (VFAs) and ammonia often destabilizes the AD process, and managing the digestate byproduct poses additional challenges. This study investigates the use of co-pyrolysis biochar synthesized from digestate and rice straw (DRB) to enhance methane production and AD efficiency. DRB addition increased cumulative methane yield by 37.1%, improved VFA conversion efficiency, and achieved a 42.3% higher NH₃-N-removal rate compared to the control group. The COD-removal rate was 68.7% throughout the process. Microbial analysis revealed that DRB selectively enriched Fastidiosipila and Methanosarcina, promoting direct interspecies electron transfer (DIET) and methane yield. These findings highlight DRB’s potential to enhance AD efficiency and support closed-loop resource utilization. Full article

Fungal chlamydospores are asexual spores formed by fungi under adverse conditions and could be used in biological pretreatment for biogas projects fed by lignocellulosic substrates. In this study, Trichoderma viride (Tv) chlamydospores were used as the pretreatment agent to enhance the methane yield of spent mushroom substrates (SMSs). Lignocellulosic composition, methanogenesis performance, and anaerobic microbial communities were investigated for different Tv pretreatment durations (0 h, 12 h, 24 h, 48 h, 96 h, and 192 h). The results showed that the optimal Tv pretreatment duration was 24 h, and the cumulative methane yield reached 173.4 mL/gVS, which was 16.8% higher than that of the control. A pretreatment duration longer than 48 h was not conducive to methanogenesis. Sequencing analysis of anaerobic microbial communities showed that the pretreatment duration was directly proportional to the relative abundance of Tv at the beginning of digestion. When the initial Tv abundance was higher than 50%, Trichoderma became the absolute dominant fungus with an abundance higher than 97% in fungal communities in the later stage of digestion. The correlation network among fungi, bacteria, and archaea showed that Tv was directly related to 11 genera, and through these taxa, Tv affected 58% of the taxa in the whole microbial network. Cost accounting showed that Tv pretreatment has a net income of 45.5 CNY/1000 kg SMS, and is a promising technology. This study provides important guidance for the use of fungal chlamydospores in pretreatment and also promotes the understanding of fungi in anaerobic digestion. Full article

Weed and disease management in organic watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] production is challenging. Yellow nutsedge (Cyperus esculentus L.) and Palmer amaranth (Amaranthus palmeri S. Wats.) are two competitor weeds in watermelon plasticulture production systems. Anaerobic soil disinfestation (ASD) is an emerging non-chemical approach to control weeds and soilborne plant pathogens, especially in organic farming. The effect of ASD treatments on weeds and soilborne diseases is being documented on different specialty crops. However, the impact of ASD treatments on the crop and crop genotypes; specifically watermelon has not been elucidated. Therefore, the impact of chicken manure and molasses (CMM)-induced ASD on twenty commercially available watermelon genotypes/rootstocks and major weed species was evaluated in a high tunnel experiment. The experiment was constructed as a randomized complete block design with three replications. The treatments consisted of a factorial of carbon source (1) non-treated check (CK), (2) CMM by twenty watermelon genotypes and rootstock. Soil treated with carbon CMM demonstrated significantly greater cumulative anaerobicity (246,963) activity relative to CK (575,372). Under anaerobic conditions, CMM achieved 91% weed control compared to CK. A lower number of yellow nutsedge (2) and Palmer amaranth (1) counts were recorded in CMM compared to CK (8) and (28), respectively. Among watermelon genotypes, ‘Extazy’, ‘Powerhouse’, ‘Sangria’, and ‘Exclamation’ had greater vigor 8.5, 8.4, 8.4, and 8.3, respectively, at 28 days after transplanting in CMM-treated soil. Greater watermelon plant fresh biomass was recorded in CMM-treated soil for ‘Extazy’ (434 g), ‘Powerhouse’ (409 g), ‘Exclamation’ (364 g), and ‘Sangria’ (360 g). This study demonstrated the variable response of watermelon genotypes to CMM-induced ASD and provides a guide for germplasm selection in organic watermelon production under field conditions. Full article

Sewage sludge was treated with nanoscale zero-valent iron (nZVI) to enhance biogas and methane (CH₄) production, and the influence of key parameters on the material’s anaerobic digestion (AD) efficiency was analyzed using sigmoidal mathematical models. In this study, three dosages of nZVI (0.5%, 1.5% and 3%) were added to the anaerobic sludge digestion system to enhance and accelerate the sludge decomposition process. The results showed that cumulative biogas yield after 41 days of digestion increased by 23.9% in the reactor with a nZVI dosage of 1.5%. Correspondingly, the highest CH₄ production enhancement by 21.5% was achieved with a nZVI dosage of 1.5% compared to the control. The results indicated that this nZVI dosage was optimal for the AD system, as it governed the highest biogas and CH₄ yields and maximum removal of total and volatile solids. Additionally, to predict biogas and CH₄ yields and evaluate kinetic parameters, eight kinetic models were applied. According to the results of the modified Gompertz, Richards and logistic models, the nZVI dosage of 1.5% shortened the biogas lag phase from 11 to 5 days compared to the control. The Schnute model provided the best fit to the experimental biogas and CH₄ data due to highest coefficients of determination (R²: 0.9997–0.9999 at 1.5% and 3% nZVI dosages), as well as the lowest Akaike’s Information Criterion values and errors. This demonstrated its superior performance compared to other models. Full article

The effects of milling on the anaerobic degradability of wheat straw and corn stover were investigated. Pretreatment was carried out by an industrial-scale device, able to process over one ton per hour. After 28 days of digestion under mesophilic conditions, the cumulative methane production from the pretreated straw (250 Nm³ t⁻¹ of volatile solids) was 49.2% greater than that from the raw material. Pretreated stover reached a cumulative methane yield of 219.8 Nm³ t⁻¹ of volatile solids, gaining 10.1% as compared to the feedstock. The specific electrical energy requirements for pretreatment were 66.6 kWh t⁻¹ for processed straw and 64.8 kWh t⁻¹ for stover; these consumptions were not significantly different. With reference to biomethane production, the impact of raw material on the production cost decreased from EUR 0.418 Nm⁻³ to EUR 0.328 Nm⁻³ for pretreated straw, whereas it increased by 5.8% for corn stover, whose pretreatment, therefore, was not economically feasible. Full article

Anaerobic digestion (AD) is a waste-to-energy strategy that leverages natural microbiological processes. It is increasingly used in farms to treat manure, resulting in biogas for energy production and digestate as fertiliser. However, animal manure often contains antibiotic (AB) residues, raising concerns about their impact on AD efficiency and their potential spread through digestate use. This multidisciplinary study evaluated the effects of an AB mixture (enrofloxacin, ciprofloxacin and sulfamethoxazole) on CH₄ production, microbial community (Fungi, Bacteria and Archaea) dynamics and antibiotic resistance gene (ARG) presence. The experiment used a cattle manure/digestate ratio of 1:35, typical of real digesters, with AB concentrations set at low (2.5 mg kg⁻¹ each) and high (7.5 mg kg⁻¹ each) levels. The ABs affected cumulative CH₄ production (ranging from 5939 to 6464 mL) only at the highest concentration. After 51 days, sulfamethoxazole reached residual levels, while enrofloxacin and ciprofloxacin were only partially degraded (<50%), but ARGs were significantly reduced. The microbial community, particularly prokaryotes, exhibited resilience, maintaining efficient CH₄ production. Overall findings strongly suggest that AD is an effective treatment for producing energy and good fertiliser, also reducing AB and ARG content as well as mitigating CH₄ emissions into the atmosphere. Full article

Livestock and poultry waste liquid contains a lot of nitrogen, phosphorus, and microorganisms, and direct discharge causes great harm to the environment. Chicken manure was selected as the research object, and nanoparticle nano-Fe₂O₃, nano-C₆₀, antibiotics enrofloxacin, sulfamethoxazole, and oxytetracycin were selected as additives to carry out medium-temperature sequential batch anaerobic digestion experiment. The experiment lasted for 55 days. The results showed that (1) gas production reached its peak in the first 1–2 days of a single stress experiment, and the cumulative gas production in the first 10 days was as follows: R5 > R4 > R3 > R2 > CK > R1; (2) the concentrations of total volatile fatty acids (TVFAs) in the groups increased rapidly from day 1 to 10, and the concentrations of TVFAs in the nano-Fe₂O₃ and nano-C₆₀ groups were higher than those in the other four groups. The pH of the system decreased, and the soluble chemical oxygen demand (SCOD) was consistent with the trend of TVFAs, while the pH of the nanoparticle group was lower; (3) changes in the horizontal structure of bacterial community of Firmicutes and Bacteroidetes were dominant bacteria in each group on the first day. On day 5, the relative abundance of actinomycetes and Bacteroidetes increased significantly. This experiment contributes to the study of the effects of adding nanoparticles and antibiotics to anaerobic digestion substrates on gas production characteristics, provides data support, and characterizes the microbial situation during digestion. This paper can help to realize carbon emission reduction in agriculture and rural areas. Based on the above background, a self-designed system for testing the anaerobic digestion potential of methane was used in this study using chicken manure. Based on the single pollutant stresses of nano-Fe₂O₃, nano-C₆₀, enrofloxacin, sulfamethoxazole, and hygromycin, the effects of different pollutants under independent stresses on methane production and the changes in the performance of the anaerobic digestion system for gas production were investigated. The chemical parameters and microbial diversity in the anaerobic digestion process were analyzed, and the effects of different nanoparticles and antibiotics on the anaerobic system of chicken manure were elucidated. The results of the study can provide data support for the stable operation of biogas projects, which is of great significance in promoting the sustainable development of ecological agriculture. Full article