Search

[Display omitted] • A cryolithophilic thermophilic nitrifying bacterial consortium (CNB) was developed. • CNB enhanced nitrite oxidoreductase's activity and elevated nxrA gene abundance. • CNB inoculation reduced NH 3 and N 2 O emissions and increased the humus content. • CNB inoculation of compost is environmentally friendly and cost-effective. Excessive nitrogen release during composting poses significant challenges to both the environment and compost quality. Biological enhancement of humification and nitrogen conservation is an environmentally friendly and cost-effective approach to composting. The aim of this study was to develop a psychrophilic and thermophilic nitrifying bacterial consortium (CNB) and investigate its role in nitrogen transformation and humification during cow manure composting. Analysis revealed that CNB inoculation promoted microbial proliferation and metabolism, significantly increased the number of nitrifying bacteria (p < 0.05), and elevated the activity of nitrite oxidoreductase and nxrA gene abundance. Compared to the control, CNB inoculation promoted the formation of NO 3 –-N (77.87–82.35 %), while reducing NH 3 (48.89 %) and N 2 O (20.05 %) emissions, and increased humus content (16.22 %). Mantel analysis showed that the higher abundance of nitrifying bacteria and nxrA facilitated the nitrification of NH 4 +-N. The improvement in nitrite oxidoreductase activity promoted NO 3 –-N formation, leading to increased humus content and enhanced compost safety. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crucial impact of initial C/N on compost process confirmed through meta -analysis. • Recommended initial C/N for pig and chicken manure composting are 20–25. • Recommended initial C/N for sheep and cow manure composting are 25–35. • Extended durations are necessary for composting at high initial C/N ratios. • Use of microbial inoculants recommended for enhancing composting at low initial C/N. Given the heterogeneity of raw materials, the diversity of composting processes, and the complexity of biological transformations, systematically exploring the critical role of the initial carbon-to-nitrogen (C/N) ratio in the aerobic composting of agricultural residues is challenging within a single experimental study. This study employs meta -analysis to investigate this role. Statistical analysis of 192 scholarly articles confirmed that most studies adhere to the recommended optimal initial C/N range of 25 and 30, where enhanced compost maturity and nutrient accumulation are observed. The findings indicate that optimal initial C/N ratios vary by agricultural residue type. A C/N ratio of 20 to 30 facilitates controlling the composting duration within 45 days, while a C/N ratio of 30 to 35 necessitates extending the duration beyond 45 days. The study highlights the effectiveness of adjusting the C/N ratio and applying microbial inoculants and physical amendments to optimize composting outcomes and control the composting duration. [ABSTRACT FROM AUTHOR]

• The significant of SRT on the hydrolysis rate and maximum uptake rate was confirmed. • The modified ADM1 was validated for AD of intact and thermally hydrolyzed CM. • The effects of thermal hydrolysis pretreatment were analyzed using model simulation. In this study, Anaerobic Digestion Model No.1 (ADM1) was modified to incorporate changes in biochemical parameters due to solids retention time (SRT) variations. Cattle manure (CM) and thermally hydrolyzed CM were selected for testing. Continuous anaerobic digestion reactors were operated under different SRT conditions ranging from 6.6 to 36.0 days for both samples. The biochemical parameters (k ch , k li , k pr , u m , a c , u m , b u , u m , p r o , u m , v a , K ac , K bu , K pro , and K va ) for each SRT condition were determined. To modify ADM1, the equations obtained through linear regression were substituted into biochemical parameters as a function of SRT. The modified ADM1 demonstrated superior accuracy compared with conventional ADM1. This study implies the feasibility of optimizing biochemical parameters for modeling in response to changes in environmental variables. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amoxicillin (AMX) and Cu decreased humification by 15.73%. • Humification was affected less by AMX and Cu together than either separately. • AMX and Cu decreased the cellulose degradation rate by 9.01%. • Bacteria played more active roles than fungi in the humification process. • AMX and Cu decreased the number of bacteria involved in humic acid formation. Livestock manure often contains various pollutants. The aim of this study was to investigate how adding amoxicillin (AMX), Cu, and both AMX and Cu (ACu) affected humification during composting and the microbial mechanisms involved. The cellulose degradation rates were 16.96%, 10.86%, and 9.01% lower, the humic acid contents were 18.71%, 12.89%, and 16.78% lower, and the humification degrees were 24.72%, 24.16%, and 15.73% lower for the AMX, Cu, and ACu treatments, respectively, than the control. Adding AMX and Cu separately or together inhibited humic acid formation and decreased the degree of humification, but the degree of humification was decreased less by ACu than by AMX or Cu separately. The ACu treatment decreased the number of core bacteria involved in humic acid formation and decreased carbohydrate and amino acid metabolism during the maturing period, and thereby delayed humic acid formation and humification. The results support composting manure containing AMX and Cu. [ABSTRACT FROM AUTHOR]

[Display omitted] • Loading rate slowly increased to 3 kg volatile solids m−3 d−1 over one year. • Inoculation did not have a large impact on the methanogenic archaeal community. • Acetoclastic methanogens dominated the full-scale digester. • Methanoculleus and Methanothrix corresponded with high methane yield. • Bacterial communities differed between the hydrolysis tank and anaerobic digester. Carbon transformations during anaerobic digestion are mediated by complex microbiomes, but their assembly is poorly understood, especially in full-scale digesters. Gene-centric metagenomics combining functional and taxonomic classification was performed for an on-farm digester during start-up. Cow manure and organic waste pre-treated in a hydrolysis tank were fed to the methane-producing digester and the volatile solids loading rate was slowly increased from 0 to 3.5 kg volatile solids m−3 d−1 over one year. The microbial community in the anaerobic digester exhibited a high ratio of archaea, which were dominated by hydrogenotrophic methanogens. Bacteria in the anaerobic digester had a high abundance of genes for ferredoxin cycling, H 2 generation, and more metabolically complex fermentations than in the hydrolysis tank. In total, the results show that a functionally stable microbiome was achieved quickly during start-up and that the microbiome created in the low-pH hydrolysis tank did not persist in the downstream anaerobic digester. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar (BC) and volcanic rock (VR) addition can enhance manure compost maturity. • BC and VR decreased the E4/E6 value by 10.42% and 11.31%, respectively. • Additives can improve Thermobacillus , Geobacillus , and Paenibacillus abundance. • BC and VR promoted maturity by adjusting bacterial abundance and metabolism. Additives are important for accelerating humification during aerobic composting. The impacts of porous additives biochar and volcanic rock on the physicochemical parameters, maturity indicators, microbial communities, and bacterial functional metabolism during the aerobic composting of cow manure were investigated in this study. The results showed that the biochar addition decreased the E4/E6 value by 10.42% and increased the abundance of Geobacillus (1.69 times), and volcanic rock addition decreased the E4/E6 value by 11.31% and increased the abundance of Thermobacillus (1.29 times) and Paenibacillus (1.72 times). The network analysis demonstrated that biochar promoted maturity by reducing the abundance of Pseudomonas and increasing the abundance of genes related to the metabolism of other amino acids, while volcanic rock promoted maturity by reducing the abundance of genes related to nucleotide metabolism. These results provided data and theoretical justification for the selection of porous additives for composting. [ABSTRACT FROM AUTHOR]

Highlights • Biomethanation of cattle manure was validated in a 100 L digester. • Permeation membranes were used to strongly limit undissolved H 2 in the biogas. • A linear relationship was clearly shown between biogas CH 4 content and H 2 flowrate. • Biogas production was probably limited by CO 2 transport within the bioreactor. Abstract This study aimed at studying the biomethanation process using a 100 L pilot-scale digester equipped with a dense membrane for hydrogen injection. Hydrogen mass transfer was characterized and the impact of hydrogen flowrate, agitation rate and of the co-injection of CO 2 , on biogas production and composition, was precisely studied. A linear relationship between H 2 flowrate and the CO 2 and CH 4 rates in biogas was found but no impact on biogas flowrate was shown. It was also noticed that, without exogenous CO 2 injection, and for high H 2 injection flowrates, residual H 2 could be found at the digester outlet due to local CO 2 limitation. Thus, this study suggested that biogas production in biomethanation process at the pilot scale was probably rather limited by the dissolved CO 2 transport within the liquid phase than by the hydrogen mass transfer itself. [ABSTRACT FROM AUTHOR]

Highlights • A quick start-up strategy was developed for biogas production in plug flow reactor. • Reflux of acidizing fluid (RAF) could effectively enhance the AD performance. • RAF could improve the microbial community structure and accelerate hydrolysis process. • This study provides a practical way for enhanced biogas production from cattle manure. Abstract The performance and microbial community succession of a 36 L working volume plug flow reactor was evaluated for treated cattle manure at an organic loading rate of 2.67 g-TS/L/day, a temperature of 38 °C ± 1 °C, and a hydraulic retention time of 18 days. A reflux of acidizing fluid effectively enhanced anaerobic digestion performance and promoted optimization of microbial community structure. The average biogas volume production rate was 1.08 L biogas/L reactor, which was 116.5% higher than the control without reflux of acidizing fluid. The specific qmethane production yield and methane content reached 0.204 L/g VS and 70%. Moreover, methane yield achieved 0.34 m3/kg removal COD with a COD removal of about 70.56%. The bacteria genera Christensenellaceae , Bacteroidales , vadinBC27 , Ruminococcaceae and Treponema_2 were further enriched. Methanosarcina became the dominant methanogen in the whole PFR operation process. This study offers new opportunities for producing renewable energy from enhanced cattle manure biodegradability. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Steel slags were firstly used as accelerants in the AD system. • Digestate with steel slag accelerants showed potential application as fertilizer. • Improved performance of AD due to the multi-elements released from steel slag. • Resource utilization and nonhazardous treatment of waste were achieved. Abstract Accelerants can effectively enhance the performance of anaerobic digestion (AD) system. The effects of optimized steel slag as accelerant in the AD of cow manure and the fertility utilization of the digestate were investigated. Results show that all steel slags collected from different iron and steel companies (slag-1, slag-2, and slag-3) positively affect AD performance in terms of enhancing the biogas yield, methane yield, and chemical oxygen demand (COD) degradation rate. The cumulative biogas yield, methane yield, and COD degradation rate of slag-2 are 507.29 mL/g VS, 274.70 mL/g VS, and 58.62%, respectively. Thermal analysis reveals that the digestate with steel slag has excellent thermal stability and potential application as a component of nitrogen, phosphorus, and potassium organic compound fertilizers. The use of different steel slags as accelerants in the AD system provides a safe and economical avenue to realize the resource utilization and harmless treatment of waste resource. [ABSTRACT FROM AUTHOR]

Highlights • Biochar combined with enriched cultures addition in cow manure composting was studied. • Bacteria diversity and abundance remarkably enhanced in composting. • 12%WSB with bacteria culture treatment has maximum abundance of Firmicutes phyla. • Bacteroidales, Flavobacteriales and Bacilli were significantly higher abundance. Abstract The present work studied to evaluate the effectiveness under the interaction of bacterial consortium and biochar applied to give impetus to bacterial community activities among cow manure composting. High-throughput sequencing technique and six treatments were carried out: T2, T3 and T6 were single apply of bacteria culture (C), 12%wood biochar (12%WB) and 12%wheat straw biochar (12%WSB), respectively, while T4 and T5 were bacterial consortium combined with 12%WB and 12%WSB respectively, and T1 was used as control. The conclusion shows that the richness of bacterial community were most prosperity in T5 and T4 that in line with the statistical analysis angle of curves and cluster. The dominate phyla of Firmicutes, Proteobacteria and Bacteroidetes were accounted to 31.36%, 34.79% and 33.85%, the superior genera were Dysgonomonas (16.55%) , Empedobater (9.39%) , Atopostipes (13.42%) , Tissierella (8.25%) , Marinimicrobium (14.45%) and Pseudomonas (9%). Overall, bacterial consortium combined with biochar could stimulate microbe activity to accelerate degradation, enhance richness and alter specific selection of bacterial community. [ABSTRACT FROM AUTHOR]

Highlights • High methane yield was obtained from anaerobic digestion of straw at 55 °C. • Syntrophic acetate oxidation was coupled to hydrogenotrophic methanogenesis. • Dominance of hydrogenotrophic methanogenesis was observed. Abstract Biomethanation of rice straw was performed at 55 °C without thermochemical pretreatment using cattle dung supplemented with Methanothermobacter thermautotrophicus strains. Methane yield of 323 ml g−1 VS obtained under optimized conditions such as particle size (1 mm), carbon to nitrogen ratio (15:1), substrate to inoculum ratio (1:1), organic loading rate (7.5% w/v) and hydraulic retention time (20 days), was one of the highest ever reported from rice straw. Metagenome analysis revealed several putative novel taxa among resident microbes. The genomes of Clostridium, Hungateiclostridium, Alkaliphilus, Anaerocolumna, Olsenella, Paenibacillus, Pseudoclostridium, Tepidanaerobacter and Turicibacter were recovered as metagenome assisted genomes. Clostridium spp. and M. thermautotrophicus were the dominant hydrolytic and methanogenic microbes, respectively. Syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis was found to be the major pathway for methane production. Efficient thermophilic biomethanation of rice straw without thermochemical pretreatment using cattle dung supplemented with M. thermautotrophicus is reported for the first time. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A large-scale plug flow reactor (PFR) was investigated for biogas production. • Efficient and stable biogas production from cattle manure was achieved in PFR. • The microbial communities in PFR were explored. • A novel approach for producing biogas in large scale from cattle manure was provided. Abstract In this study, a large-scale plug flow reactor has been operated at a hydraulic retention time of 25 d with substrate concentration of total solids (7–10%) under a temperature of 37–40 °C with a working volume of 3.85 × 104 m3 and dispose 1504 m3/d of waste for three years. The average monthly biogas production was 7.45 × 104 m3. At stable stage, the volume biogas, methane production rate and methane content reached 1.07 m3/m3·d, 0.58 m3/m3·d and 56.4%, respectively. Moreover, the specific biogas and methane yields of substrate removal efficiency were up to 0.39 m3/kg VS, 0.22 m3/kg VS and 59%, respectively. Among the bacteria, the genera Draconibacteriaceae , Ruminofilibacter , Cloacimonete s and vadinBC27 , Ruminiclostridium and Treponema_2 dominated in digestate. The achaeal was dominated by methanogens genera Methanosarcina and Bathyarchaeota. Long-term operation in large scale demonstrated technological potential and industrial application of cattle manure treatment for biogas production. [ABSTRACT FROM AUTHOR]

Highlights • Co-digestion of Laminaria digitata and cattle manure improved the bioenergy output. • Laminaria digitata enhanced biogas yield and cattle manure provided buffer capacity. • Results from batch and continuous reactor were confirmed by BioModel simulation. • BioModel could be used as a practical and multi-purpose simulation tool. Abstract This work investigated the thermophilic (55 °C) co-digestion performance both in batch and continuous mode operation. The biochemical methane potentials of L. digitata and cattle manure were 308 ± 24 and 203 ± 33 mL CH 4 /g VS, respectively. The optimum co-digestion feedstock ratio was found to be 80% macroalgae: 20% manure on a volatile solids basis, which produced 290 ± 19 mL CH 4 /g VS under long-term and stable continuous operation at an organic loading rate of 2 g VS/L/d and hydraulic retention time of 15 days. Simulations of the batch and continuous experiments were, for the first time, carried out using an integrated anaerobic bioconversion model without structural modifications. Close fits between measured and simulated data provided mutual confirmation of experimental reliability and model robustness, and provided new perspectives for the use of the software tool. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Technological transference from laboratory scale to rural area in a developing country. • Energy available as Biogas to replace traditional fuels in non-interconnected areas. • Use of a low cost technique to estimate quantity and quality of microbial community in inoculum. • Structure, dynamics and balance are indicators of microbial population behavior in inoculum. Abstract The aim of this work was to use an inexpensive technique, such as the most probable number, MPN to quantitatively and qualitatively examine microbial groups in anaerobic digestion, AD of cattle manure, CM. Different diluents and mixing ratios were evaluated in 100 mL reactors using biomethane potential, BMP, as output variable. MPN tests were performed to samples from a 23 L tank and 6.5 m3 low-cost tubular digester, LCTD. To monitor LCTD stability, volatile solids, VS, specific methanogenic activity, SMA, pH, volatile fatty acids, VFA, and chemical oxygen demand, COD were measured. Microbial characterization highlighted the optimal population essential to initiate the anaerobic digestion process. Bacteria domain were predominant over Archaea, with average abundance values of 78% and 22%, respectively. SMA of 0.0486 g COD g−1 SV d−1 was obtained at laboratory-scale and LCTD reached 83% of this value. Conditions selected are cost-effective to establish a biodigester in rural areas. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel method of lignocellulose pretreatment by electroporation was developed. • SEM analysis revealed structural changes in harvest residues after pretreatment. • Electroporation improved anaerobic co-digestion of harvest residues. • A positive energy balance was achieved. Abstract The aim of this research was to develop a method for pretreatment of lignocellulose (LC) substrates (harvest residues (HR)) via electroporation (EP) for the purpose of improving the biogas production process. In addition, pretreated LC substrates were analyzed by scanning electron microscopy (SEM) and the energy balance of the total process was calculated. After the conducted pretreatment and anaerobic co-digestion with dairy cow manure (DCM), the statistical data analysis showed statistically significant differences in biogas and/or methane yield for all three LC substrates and their fractions. It was concluded that, after the pretreatment of LC substrates via EP, it is possible to improve the anaerobic co-digestion process and to achieve positive energy balance of the total process. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Database gathering performance data on more than 60 full-scale digestate separators. • Classification of separators into low and high-performance equipment. • Very distinct profiles of digestate components separation. • Dependency of separator choice and AD feedstock. • Simple approach to predict digestate separation based on equipment and AD feedstock. Abstract Digestate mechanical separation is present in numerous anaerobic digestion plants. In this study, data from literature and from unpublished analysis were gathered to evaluate digestate separation efficiency for different mechanical separators. For the first time, efficiency indicators allowed the definition of two mass distribution profiles. The low-performance profile was characterized by each component being mainly destined to the liquid fraction, excluding P, Mg and Ca in a few cases. Screw presses represented 68% of these separators and 78% of digestates came from mainly fibrous inputs such as cow manure and silage. In the high-performance profile, digestate compounds were effectively concentrated in the solid fraction, except nitrogen. The great majority of separators were decanting centrifuges, and the anaerobic digestion inputs were principally non-fibrous such as pig slurry, sludge and agro-industrial waste. This study represents a source for benchmarking digestate separation and opens a possibility to forecast more realistically digestate separation performance. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Solid-state anaerobic digestion (SAD) removed over 7/10 ARGs from digestion product. • The variations in the bacterial community were smaller in SAD than LAD. • Firmicutes comprised 62.5% of the potential hosts for ARGs and MGEs. • SAD decreased the environmental risk of ARGs in the manure digestion product. Abstract Livestock manure is a hotspot for antibiotic resistance genes (ARGs). Solid-state anaerobic digestion (SAD) is a high efficiency livestock manure treatment, but the changes in ARGs and microbial communities during SAD are unknown. Therefore, thermophilic SAD (55 °C), mesophilic SAD (35 °C), and liquid anaerobic digestion (35 °C) were conducted to investigate the impacts of SAD on ARGs, mobile genetic elements, and microbial communities. Compared with liquid anaerobic digestion, SAD significantly reduced at least 7/10 ARGs and all of the mobile genetic elements considered, where the total abundance of ARG was 23.7% higher in the thermophilic SAD product than the mesophilic SAD product. Firmicutes and Proteobacteria were the main potential hosts for ARGs, and their decreased abundances were mainly responsible for the reductions in ARGs during SAD. This study demonstrated that SAD is a promising method for decreasing the ARGs risk in livestock manure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Inoculants improved compost quality and reduced nitrogen loss during composting. • Inoculants reduced NH 3 emission and the N 2 O emission by 24.8–36.1% and 22.7–32.1%. • Inoculants change the structure and diversity of microbial community. • Inoculants down-regulated the nirS , norC , nap and nif and upregulated the hao. The impacts of microbial agents on nitrogen conversion during composting is still not entirely clear. In this research, a novel microbial agent containing two thermotolerant nitrifying bacteria was identified and its impacts on nitrogen conversion, bacterial structure and functional genes during cattle manure composting were investigated. The results revealed that the inoculation enhancing the maturation of compost, increased the total nitrogen by 13.6–26.8%, reduced NH 3 emission and the N 2 O emission by 24.8–36.1% and 22.7–32.1%, respectively. Particularly, the microbial agents mixed Acinetobacter radioresistens and Bacillus nitratireducens (1:1, treatment group 1) had the best nitrogen preservation effect. Furthermore, the inoculation not only produced diverse diazotroph community but could strength the co-occurrence between core microorganisms to promote nitrogen metabolism. The metagenomic analysis demonstrated that the inoculation decreased the abundance of nitrate reduction gene (nirS , norC , nap and nif) , and increased the abundance of hao , thus facilitating nitrification and suppressing NH 3 and N 2 O emission. [ABSTRACT FROM AUTHOR]

[Display omitted] • CZnONPs and GZnONPs mitigated the dissemination risks of ARGs in cattle manure. • The GZnONPs group exhibited a significant reduction in manure zinc content. • Different QS-related KEGG Orthology caused changes in expression patterns of ARGs. • Zinc selection pressure during anaerobic fermentation affected the ARG profiles. • Dominant ARG subtypes were shifted because of the changing abundance of ARG hosts. This study used metagenomic sequencing to examine the effects of carbon-based zinc oxide nanoparticles (CZnONPs) and graphene-based zinc oxide nanoparticles (GZnONPs) on quorum sensing (QS), antibiotic resistance genes (ARGs) and microbial community changes during cattle manure production. The manure zinc content was significantly reduced in GZnONPs group. In the QS pathway, the autoinducer gene increases significantly in Control group, while the transporter and repressor genes experience a substantial increase in CZnONPs group. These results contributed to the significantly decreased the abundance of ARGs in GZnONPs group. The co-occurrence network analysis revealed a correlation between core ARGs and QS-related KEGG Orthology or ARGs' hosts, indicating that the selective pressure of zinc influences microbial QS, forming a unique ARG pattern in in vivo anaerobic fermentation. These findings suggest that implementing nutritional regulation in farming practices can serve as a preventive measure to mitigate the potential transmission of ARGs resulting from livestock waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • ARGs fate in 6 industrial-scale aerobic composting plants was studied. • Rapid composting would lead to a rebound in ARGs abundance. • Traditional composting performed better than rapid composting in ARGs removal. • Organic waste species determined the contamination status of ARGs. • MGEs and heavy metals were key factors influencing ARGs dynamics. This study investigated the fate of antibiotic resistance genes (ARGs) and bacterial evolution in six industrial-scale organic wastes aerobic composting plants and identified key factors driving ARGs dynamics. A total of 226 ARGs and 46 mobile genetic elements (MGEs), mainly resistant to aminoglycoside and MLSB, were detected by high-throughput qPCR. Briefly, aerobic composting showed good performance in reducing the diversity and abundance of ARGs, where the total absolute abundance was reduced by 88.34%–97.08% except for cattle manures. Rapid composting may lead to a rebound of ARGs due to long-term storage compared to traditional composting. Hub ARGs and bacterial genera were screened out by co-occurrence patterns. As the dominant phyla in composting, the main potential hosts of ARGs were Firmicutes , Bacteroidota and Proteobacteria. Structural equation model indicated that MGEs and heavy metals were key factors affecting ARGs dynamics. In addition, nutrients and bacterial α-diversity can indirectly influence ARGs by affecting MGEs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Cow manure (1/3) functioned as a stimulant during oat straw anaerobic digestion. • Addition of cow manure affected methane yield more than the total solids content. • C/N ratio = 27 was suitable for anaerobic digestion of oat straw waste and cow manure. • Higher methane yields were due to the increasing degradation of cellulose. • Clustering analysis provided significant guidance for demonstrating project process. Abstract Impacts of adding different amounts of cow manure (CM) on the anaerobic digestion (AD) of oat straw (OS) with total solids content (TS) values of 4%, 6%, 8% and 10% was assessed over 50 days using batch experiments. A modified Gompertz model was introduced to predict the methane yield and determine the kinetic parameters. The optimum addition was a 1:2 ratio of CM to the OS added, which resulted in a suitable C/N ratio of 27 and a higher degradation rate of lignocellulose. The best cumulative methane yield of 841.77 mL/g volatile solids added (VS added) was 26.64% greater than that of digesting OS alone. In addition, the amount of CM added produced larger effects than that of changes in the TS. However, higher CM concentrations were found to be inhibitory. Clustering analysis could provide significant guidance for demonstrating project process and combining farming and animal husbandry. [ABSTRACT FROM AUTHOR]

Succession of bacterial community, metabolism function and substrate utilization capacity in 60 days composting of cow manure were analyzed by 16S rRNA pyrosequencing, PICRUSt and Biolog method, respectively. The results showed that the number of bacterial OTUs increased from 176 in raw cow manure to 203 on Day-10, 220 on Day-30 and 313 on Day-60 of the composting, respectively. The PICRUSt analysis showed that the relative abundances of genes involved in lipid and carbohydrate metabolism increased by 28.5% and 22.4% during the incubation, respectively, but the abundances of the genes involved in nucleotide and amino acid metabolism decreased by 21.6% and 2.1%. Furthermore, the average well color development (AWCD) of carboxylic acids (0.99–0.48) and amino acids (1.61–0.89) in Biolog Eco-microplate displayed a steady downtrend through the composting process. Redundancy analysis showed that ORP, moisture and temperature could explain 68.1%, 17.6% and 14.2% of the variation in bacterial genera, respectively. [ABSTRACT FROM AUTHOR]

In this study, dynamic changes in fungal communities, trophic modes and effect factors in 60 days composting of cow manure were analyzed by using high throughput sequencing, FUNGuild and Biolog FF MicroPlate, respectively. Orpinomyces (relative abundance >10.85%) predominated in feedstock, and Mycothermus became the dominating genus (relative abundance >75%) during the active phase. Aerobic composting treatment had a significant effect on fungal trophic modes with pathogenic fungi fading away and wood saprotrophs increasing over composting time. Fungal communities had the higher carbon sources utilization capabilities at the thermophilic phase and mature phase than those in the other periods. Oxidation reduction potential (ORP) significantly increased from −180 to 180 mV during the treatment. Redundancy analysis showed that the succession of fungal community during composting had a significant association with ORP (p < .05). This indicated that aerobic composting treatment not only influenced fungal community structure, but also changed fungal trophic modes and metabolic characteristics. [ABSTRACT FROM AUTHOR]

The objective of the present study is to assess the impact of TS concentration, substrate mixing ratio (co digestion) and thermal pretreatment on biogas production, methane yield, VS reduction (%) and quality of biomanure through dry anaerobic digestion (DAD) of food waste (FW) and cattle manure (CM). Results divulged that the optimum methane yield and biomanure of 0.18 and 0.21 m 3 CH 4 /(kg VS reduced) and 3.15 and 2.8 kg/kg waste was obtained from FW at TS of 25% and 30% at an HRT of 41 and 31 days respectively whereas it was 0.32 and 0.43 m 3 CH 4 /(kg VS reduced) and 2.2 and 1.15 kg/kg waste from pretreated FW at an HRT of 16 and 20 days correspondingly. Improvement of methane from 62 to 81% was obtained due to thermal pretreatment. The highest nutrient recovery in terms of N, P, K was found to be 5.14, 2.6 and 3.2 respectively. [ABSTRACT FROM AUTHOR]

The objective of this research was to use white-rot fungus Trametes versicolor for corn silage pretreatment and to investigate the effect of pretreatment on biogas productivity. Semi-continuous pilot-scale experiment, comprised of two experimental phases, was carried out. In the first phase, operational conditions of the full-scale biogas plant were reproduced at pilot-scale. In that phase, the reactor was daily fed with the mixture of cow manure, digestate from industrial postfermentor, corn grits and ensiled corn silage, and the average methane generation rate was 0.167 m 3 CH4  kg VS −1 . In the second phase, corn grits and ensiled corn silage were replaced with corn silage pretreated with T. versicolor , and the average methane generation rate increased up to 0.236 m 3 CH4  kg VS −1 . The results of this study suggest that application of fungal-based solid-state pretreated corn silage has positive effect on pH stability and increase the biogas productivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • THP improved the performance of AD of CM by 1.4 times compared to the control. • By applying THP, HRT can be shortened from 36 to 13.2 d without performance loss. • THP application greatly affected the microbial community. • The reactor stability decreased with shortening of HRT, and application of THP. In this study, we investigated the potential of thermal hydrolysis pretreatment (THP) to reduce the hydraulic retention times (HRTs) in the anaerobic digestion (AD) of cattle manure (CM). The AD with THP (THP AD) outperformed the control AD by over 1.4 times in terms of methane yield and volatile solid removal, even under the same HRT conditions. Remarkably, even when the THP AD was operated with an HRT of 13.2 d, it performed better than the control AD operated with an HRT of 36.0 d. In THP AD, there was a shift in the dominant archaeal genus responsible for methane generation from Methanogranum (at HRT of 36.0 – 13.2 d) to Methanosaeta (at HRT of 8.0 d). However, decreasing HRT, and applying THP resulted in reduced stability, accompanied by increased inhibitory compounds, and changes in the microbial community. Further confirmation is required to assess the long-term stability of THP AD. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel bacterial consortium (CBC) was constructed from a wood-feeding termite. • The constructed consortium efficiently reduced 47% of lignocellulosic content. • Bacterial pretreatment enhanced biogas (156%) and methane (238%) production. • An increase in energy production (70%) when compared to the untreated digesters. • CBC was effective in willow sawdust degradation and bioenergy applications. This study was designed to develop a cellulase-producing bacterial consortium (CBC) from wood-feeding termites that could effectively degrade willow sawdust (WSD) and consequently enhance methane production. The bacterial strains Shewanella sp. SSA-1557, Bacillus cereus SSA-1558, and Pseudomonas mosselii SSA-1568 exhibited significant cellulolytic activity. Their CBC consortium showed positive effects on cellulose bioconversion, resulting in accelerated WSD degradation. After nine days of pretreatment, the WSD had lost 63%, 50%, and 28% of its cellulose, hemicellulose, and lignin, respectively. The hydrolysis rate of treated WSD (352 mg/g) was much higher than that of untreated WSD (15.2 mg/g). The highest biogas production (66.1 NL/kg VS) with 66% methane was observed in the anaerobic digester M−2, which contained a combination of pretreated WSD and cattle dung in a 50/50 ratio. The findings will enrich knowledge for the development of cellulolytic bacterial consortia from termite guts for biological wood pretreatment in lignocellulosic anaerobic digestion biorefineries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Particle size of branch on enzymatic activity and gaseous emissions during composing were assessed. • The contaminations of greenhouse gases were regulated by amending 2 cm of branch. • The active microbial assimilation and catabolism were ameliorated by applying 2 cm of branch. • The application of 2 cm of branch facilitated the enzymatic activities by optimizing benefiting habitat. The purpose of current study was to probe the effect of various length of branch on gaseous emissions and vital enzymatic activity. Four lengths (< 2 cm, 2 cm, 5 cm, and > 5 cm) of clipped branch were mingled with collected pig manure for 100 days aerobic fermentation. The consequence demonstrated that the amendment of 2 cm of branch showed conducive to decline the greenhouse gas emissions, which the CH 4 emissions decreased by 1.62–40.10%, and the N 2 O emissions decreased by 21.91–34.04% contrasted with other treatments. Furthermore, the peak degree of enzymatic activities was also observed in 2 cm of branch treatment by the optimizing living condition for microbes. In view of microbiological indicators, the most abundant and complex bacterial community could be monitor in 2 cm of branch composting pile, which verified the microbial facilitation. Summing up, the strategy of 2 cm branch amendment would be recommended. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aerobic co-composting was performed by adding mature compost to cattle manure. • Addition of mature compost contributes to lignocellulosic degradation. • Mature compost increased carbohydrate-active enzymes activity. • Addition of mature compost increased the synergistic effect between microorganisms. The production of organic fertilizer by aerobic composting of cattle manure is an important way of its resource utilization. This study evaluated the effects of adding mature compost on the decomposition and microbial communities in the aerobic composting of cattle manure. The addition of mature compost shortens the composting cycle and results in a final lignocellulosic degradation rate of 35%. Metagenomic analysis showed that this was due to the proliferation of thermophilic and organic matter-degrading functional microorganisms, which enhanced the activity of carbohydrate-active enzymes. With the addition of mature compost, the microbial community exhibited stronger metabolic functions, especially carbohydrate and amino acid metabolism, which are the driving forces of organic matter degradation. This study deepens the understanding of organic matter conversion and microbial community metabolic functions when mature compost is used for livestock manure composting and provides a promising technology for livestock manure composting. [ABSTRACT FROM AUTHOR]

• Both Thermomonospora and Modestobacter were the major DNRA bacteria. • The abundance of nrfA increased in the later phases of composting. • Denitrification and DNRA microbial interactive networks were identified. • NO 2 −-N was the main limiting factor for DNRA microbial community. This study investigated denitrification and dissimilatory nitrate reduction to ammonium (DNRA) competition for nitrite in composting of sugarcane pith and cow manure. Metagenomic analysis showed that Actinobacteria was the main DNRA microorganism. During heating phase and thermophilic phase, the abundances of denitrification functional genes (nirK and nirS decreased by 40.22% and 98.60%, respectively) and DNRA functional genes (nirB , nirD increased by 195.24% and 176.61%, and nrfA decreased by 45%, respectively) showed different trends. Interestingly, the abundance of nrfA increased by 250% during cooling and maturity phases. Mantel test revealed that competition between denitrification and DNRA microorganisms for NO 2 −-N limited the succession of their respective communities (P < 0.01). Network analysis showed that unclassified Solirubrobacterales , Altererythrobacter and Microbacterium were the key microorganisms in DNRA microbial communities. The results provided new insights into the key microorganisms and their driving factors affecting DNRA and nitrogen management in the composting ecosystems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cellulose-degrading bacterial and fungal community constitute co-degradation system. • Keystone decomposing fungi are the foundation of co-degradation systems. • Cellulose co-degradation system is controlled by C/N and HA/FA of the composting. To excavate a complex co-degradation system for decomposing cellulose more efficiently, cellulose-degrading bacteria, including Bacillus subtilis WF-8, Bacillus licheniformis WF-11, Bacillus Cereus WS-1 and Streptomyces Nogalater WF-10 were added during maize straw and cattle manure aerobic composting. Bacillus and Streptomyces successfully colonized, which improve cellulose degrading ability. Continuous colonization of cellulose-degrading bacteria can promote the fungi to produce more precursors for humus and promote the negative correlation with Ascomycota. In the current study, the addition of cellulose-degrading bacteria has resulted in the rapid development of Mycothermus and Remersonia in the phylum Ascomycota as keystone fungal genera which constitute the foundation of the co-degradation system. Network analysis reveals the complex co-degradation system of efficient cellulose bacteria and mature fungi to treat cellulose in the process of straw aerobic composting mainly related to the influence of total carbon (TC) /total nitrogen (TN) and humic acid (HA)/fulvic acid (FA). This research offers a complex co-degradation system more efficiently to decompose cellulose aiming to maintain the long-term sustainability of agriculture. [ABSTRACT FROM AUTHOR]

[Display omitted] • Identified the role of low moisture content on H 2 S emission. • The KEGG pathway of H 2 S production by sulfate reduction was constructed. • The reduction of sulfate-reducing gene abundance weakened the sulfate reduction. • Change in the abundance of functional microorganisms was key to reduce H 2 S emission. The sulfate reduction reaction releases malodorous gases (H 2 S) during composting, with potential pollution risks to the environment. In this study, chicken manure (CM) with high sulfur content and beef cattle manure (BM) with low sulfur content were used to investigate the effect of control (CK) and low moisture content (LW) on sulfur metabolism. The results showed that compared to CK composting, the cumulative H 2 S emission of CM and BM composting decreased by 27.27% and 21.08% under LW condition, respectively. Meanwhile, the abundance of core microorganisms related to sulfur components was reduced under LW condition. Furthermore, the KEGG sulfur pathway and network analysis suggested that LW composting weakened the sulfate reduction pathway, and reduced the number and abundance of functional microorganisms and genes. These results indicated that low moisture content had important effects on inhibiting the release of H 2 S during composting, which provided a scientific basis to control environmental pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Batch and semi-continuous co-digestion of CM and SEPW were implemented. • A modified ADM1 containing furfural degradation process was established. • Furoic acid was introduced as an intermediate in furfural degradation. • Modified ADM1 was used to simulate batch and semi-continuous AD. • Furfural tolerance of batch and semi-continuous systems were evaluated. In this study, an extended Anaerobic Digestion Model No.1, which considered the degradation and inhibition properties of furfural, was established and implemented to simulate the anaerobic co-digestion of steam explosion pulping wastewater and cattle manure in batch and semi-continuous modes. Batch and semi-continuous experimental data helped calibrate the new model and recalibrate the parameters related to furfural degradation, respectively. The cross-validation results showed the batch-stage calibration model accurately predicted the methanogenic behavior of all experimental treatments (R2 ≥ 0.959). Meanwhile, the recalibrated model satisfactorily matched the methane production results in the stable and high furfural loading stages in the semi-continuous experiment. In addition, recalibration results revealed the semi-continuous system tolerated furfural better than the batch system. These results provide insights into the anaerobic treatments and mathematical simulations of furfural-rich substrates. [ABSTRACT FROM AUTHOR]

• The addition of biochar and FeSO 4 reduce NH 3 and N 2 O emissions by 52.4 and 35.6%. • The addition of biochar and FeSO 4 increased the abundance of amoA and narG. • Biochar and FeSO 4 addition mitigate nitrogen loss by affecting the nitrogen flux. This study investigated the impacts of adding FeSO 4 and biochar to cattle manure and rice straw composts on functional genes controlling nitrogen loss, bacterial community, nitrification, and denitrification. Four treatments were established, including a control group (CP), and CP mixtures that included 4% biochar (TG1), 4% FeSO 4 (TG2), or 2% FeSO 4 and 2% biochar (TG3). Compared to CP, TG1–3 had a lower total nitrogen loss rate, and TG3 resulted in reduced NH 3 (52.4%) and N 2 O (35.6%) emissions to mitigate nitrogen loss. The abundance of amoA and narG gene in TG3 was higher than in the other groups, and TG3 was beneficial to the growth of Proteobacteria and Actinobacteria. According to redundancy and Pearson analysis, TG3 had a positive effect on the nitrification process by increasing the abundance of amoA and narG. Thus, biochar and FeSO 4 addition mitigate nitrogen loss by regulating the nitrification processes. [ABSTRACT FROM AUTHOR]

The environmental impacts resulting from the cradle-to-grave life cycles of Enteromorpha prolifera macroalgae and cattle manure biorefineries are assessed and compared. Sensitivity analysis is carried out to evaluate the response of the impacts to changes in biogas application by using Simapro 7.3.3. Three scenarios are considered in the biorefineries. In the first and second scenarios, the biogas produced is considered to be used for electricity production and transportation, respectively. In the third scenario, the biogas is considered to be recycled back to the systems. Process energy requirements and transportation of inputs contribute the largest share of the overall impacts. The cattle manure biorefinery is slightly more eco-friendly than the macroalgae biorefinery in Scenarios 1 and 2 because it requires more eco-friendly inputs. However, the macroalgae biorefinery becomes more eco-friendly than the cattle manure biorefinery in Scenario 3 because macroalgae require less energy and water for biogas production. [ABSTRACT FROM AUTHOR]

The thermogravimetric (TG) experiments of cattle manure were carried out from room temperature to 900 °C at five different heating rates (10, 20, 30, 40 and 50 °C/min) and the kinetics of the main decomposition process were analyzed with different methods. TG curves indicate that the major decomposition process of cattle manure could be roughly divided into three stages. The average activation energy of each stage calculated by Coats-Redfern method are 68.95, 2.63 and 55.32 kJ/mol respectively. The kinetic parameters given by Distributed Activation Energy Model method, Flynn-Wall-Ozawa method and Vyazovkin method are all show that the activation energies keep stable (at around 122.4, 126 and 123.8 kJ/mol respectively) under 60% conversion degree and then changed dramatically (ranging from 129.9 to 454.9 kJ/mol). Power law (P3) was determined as an appropriate reaction mechanism using master-plots method. The kinetic parameters calculated by Vyazovkin method can give the best agreement with the experimental results. [ABSTRACT FROM AUTHOR]

The purpose of this work was to assess the behaviour of anaerobic digestion of cattle manure in a rural digester under realistic conditions, and estimate the quality and properties of the digestate. The data obtained during monitoring indicated that the digester operation was stable without risk of inhibition. It produced an average of 0.85 Nm 3 biogas/d at 65.6% methane, providing an energy savings of 76%. In addition, the digestate contained high nutrient concentrations, which is an important feature of fertilizers. However, this method requires post-treatment due to the presence of pathogens. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effect of pre-treatment and F/M (Food to Microorganism) ratios for the rapid generation of volatile fatty acids (VFA) from livestock organic wastes (cattle manure (CM) and poultry litter (PL)) through an anaerobic acidification process at a pH range of 4.5–5.5. Experiments were organized using CM and PL in batch reactors (1 L and 25 L) with and with no pre-treatment of substrate at F/M ratios (0.4, 0.6, 0.8 and 1). Among various existing pre-treatments methods, thermal-acidic (120 °C; 1% H 2 SO 4 ) pre-treatment was found effective. The results revealed that 0.31 and 0.47 kg VFA/(kg VS reduced) could be obtained from CM and PL respectively with no pre-treatment, whereas it improvised to 0.43 and 0.67 kg VFA/(kg VS reduced) correspondingly due to pre-treatment. Aforesaid, better yield of VFA was obtained at F/M ratio of 1.0, pH-5.5 and hydraulic residence time of 4 days. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess technically and economically the application thermochemical pretreatment in the anaerobic digestion of dairy cow manure. After selecting the optimum substrate to inoculum (S/I) ratio in a preliminary BMP test, the following tests compared 20 different pretreatment conditions varying temperature (100 and 37 °C), exposure time (5 and 30 min and 12 and 24 h) and chemical doses (0.5, 2, 6 and 10% of HCl or NaOH). The highest value of maximum production rate was achieved at an S/I ratio of 0.25 g VS s g VS i −1 . The major improvements of the methane potential were 23.6% with 10% of NaOH at 100 °C for 5 min and 20.6% with 2% of HCl at 37 °C. The technical-economic analysis showed that the implementation of neither thermal alkali nor thermal-acid pretreatment would be feasible and the conventional one-step anaerobic digestion outperforms both alternatives. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bioconversion of aquatic weed biomass into soil conditioner through a two-stage biodegradation process. • Optimised biodegradation reduces the degradation period to 27 days. • Metagenomic profiling signifies the dominance of Bacteroidetes during biodegradation. • The biodegradation process was coherent in 71% volume reduction and SGI greater than 95% of feedstock. • Fed-batch feeding of weed biomass, 250 kg/day and vermicompost production of 100 kg/day. Eichhornia crassipes is a common, abundant aquatic weed biomass found globally. The present study examined optimum biodegradation procedures through batch studies (550 L rotating drum composter) and the resulting best combination on a large scale (5000 L rotary drum composter). The pilot scale rotary drum reactor was commenced with cow manure and then treated for 3 months with 250 kg/day of homogenously mixed E. crassipes and dry leaves. The rotary drum's inlet and outlet temperatures were 60 °C and 39 °C, respectively, suggesting thermophilic conditions with a 7-day waste retention duration. Eisenia fetida was used for vermicomposting the outlet material for 20 days, raising the nitrogen content to 3.2%. Bacterial diversity (16S-rRNA) sequencing revealed that Proteobacteria and Euryarchaeota are the most predominant. After 27 days, the volume dropped by 71%, and the product was stable and soil-safe. Large-scale optimised biodegradation may be a better way to handle aquatic weed biomass. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of air mixing on high-solids anaerobic digestion of cow manure was studied. • Optimal air mixing intensity of 37.5 mL/(L·min) enhanced CH 4 production by 13 %. • Air mixing improved the hydrolysis of macromolecular substrate and carbon recovery. • Air mixing enriched SOB, SAOB and aceticlastic methanogen. • Predicted hydrolase demonstrated high abundance under air mixing condition. This study aimed to further investigate the effect of air mixing on the performance of a high-solids anaerobic digestion system and reveal its underlying mechanisms via analyses of carbon conversion, microbial communities and key functional genes. When the air mixing intensity was 12.5, 37.5 and 62.5 mL/(L‧min), compared with the anaerobic digestion without air mixing, the methane yield was increased by 6 %, 13 % and 6 %, respectively. The improved performance was partly attributed to the increased hydrolysis rate of macromolecular substances by 5 %–16 % and carbon recovery in the form of methane by 6 %–7% compared with the controls. Functional flora (Magnetospirillum , Synergistaceae) and hydrolytic metabolism-related enzymes (cellulose, α-amylase) demonstrated higher abundance under air mixing condition, thus promoting the degradation of organic matter and methane production. This work provides some new insights into the use of air mixing to improve anaerobic digestion of high-solids waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • Adding bone charcoal (BC), pumice (PM), or straw carbon (SB) improved the composting. • Results were better with addition of 10 % PM than with addition of 10 % BC or 10 % SB. • Adding 10 % PM increased the relative abundance of bacteria related to nitrification. • Adding 10 % PM increased the OM degradation rate by 26 % relative to the control. • 10 % PM shortened composting period of forest residues with cattle manure to 39 days. Co-composting of forest residues (FR) with cattle manure (CM) results in a low nitrogen (N) conversion efficiency, a low organic matter (OM) degradation rate, and a low quality compost product. This study evaluated the effects of addition of bone charcoal (BC), pumice (PM), or straw biochar (SB) at a ratio of 10 % (w/w) on the co-composting of FR with CM. The highest quality compost was obtained with addition of 10 % PM. Compared with the control (without any additive), PM addition increased the OM degradation rate, the nitrate-N, the available phosphorus, and the available potassium by 25 %, 110 %, 24 %, and 9 %, respectively, and increased the relative abundance of bacteria (Planomicrobium , Flavobacterium , and Pseudomonas) involved in lignocellulose degradation and N transformation. With the addition of PM, the co-composting of FR with CM generated a high quality, useful product in only 39 days. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biochar altered the transformation relationships from ONCs to NH 4 +-N. • Biochar up-regulated nir gene transcription but inhibited NIR activity. • Denitrifying bacteria could participate in the process of ONCs transformation. • Denitrification is dominated by nirK -denitrifiers rather than nirS -denitrifiers. • Biochar altered single and combined nir -denitrifier co-occurrence patterns. This study explored the coupling relationships between denitrifiers and N -transformation using multi-level (DNA, RNA and enzyme) and multi-aspect (abundance, diversity, structure, key community, network pattern, and functional module) analyses during cattle-manure (CM) and biochar (CMB) composting. Amino sugar-N (ASN, 0.914) and hydrolysable unknown-N (-0.724) were main organic-N components mediating NH 4 +-N in CM and CMB, respectively. Biochar lowered nirK , nirS , and nosZ genes copies, up-regulated nir gene transcripts, and inhibited nitrite reductase (NIR) activity. For nirK -denitrifiers, Luteimonas was predominant taxa influencing NO 2 −-N and amino acid-N (AAN). Unclassified_k_norank_d_Bacteria and unclassified_p_Proteobacteria regulated NO 3 −-N and ASN, respectively. These three genera played crucial roles in mediating NIR activity and nosZ/nirK. For nirS -denitrifiers, Paracoccus and Pseudomonas mediated NH 4 +-N and AAN, respectively, and they were vital genera regulating NO 3 −-N, ASN and NIR activity. Furthermore, nirK -denitrifiers was major contributor to denitrification. Overall, functional denitrifiers might simultaneously participate in multiple N -transformation processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fifty microbial strains with antagonistic activity were isolated from compost. • Two compost-indigenous strains as inoculum for compost secondary fermentation. • Inoculation of B282 or F288 shifted microbial community structure of compost. • Inoculation of B282 or F288 improved antifungal activity of compost. • Inoculation of B282 or F288 enhanced control efficacy of compost in wheat root rot. Antimicrobial activity contributes to plant disease control property of composts but its source is still not clear. From composting cow manure during secondary fermentation, 50 microbial strains with antifungal activity were isolated and identified. Two bacterial strains Bacillus mojavensis B282 and Pseudomonas aeruginosa F288, antagonistic against both phytopathogenic fungi and bacteria, were respectively used as the inoculum of compost for secondary fermentation. Inoculation of B282 or F288 significantly shifted microbial community structure of compost and genera functionally linked to antagonistic activity and plant growth promotion were enriched. Notably, culturable cells of B282 increased by about 40 times during secondary fermentation. The inoculation of each strain significantly increased antifungal activity of compost extracts and enhanced disease suppressive effects of compost on wheat root rot. This study demonstrates that inoculation of compost-indigenous microorganisms could improve antimicrobial activity of compost and provides a low-cost strategy for producing bio-organic fertilizers with biocontrol function. [ABSTRACT FROM AUTHOR]

This study investigated the effects of adding Cu(II) at two exposure levels (50 and 500 mg kg −1 , i.e., Cu50 and Cu500 treatments, respectively) on the activity of ammonia-oxidizing microorganisms during dairy cattle manure composting. The results showed that the pH, NH 4 + -N, NO 3 − -N, and potential ammonia oxidation values were inhibited significantly by the addition of Cu(II). Furthermore, the abundances of the ammonia-oxidizing archaea (AOA) amoA gene and ammonia-oxidizing bacteria (AOB) amoA gene were determined by quantitative PCR, and their compositions were evaluated by denaturing gradient gel electrophoresis (DGGE). AOA was the dominant ammonia oxidizing microorganism, of which the abundance was much higher than AOB during composting. Cu50 and Cu500 had significant inhibitory effects on the abundance of the amoA gene. The DGGE profile and statistical analysis showed that Cu(II) changed the AOA and AOB community structure and diversity, where Nitrosomonas and Crenarchaeota dominated throughout the composting process. [ABSTRACT FROM AUTHOR]

The use of enzymes to improve anaerobic co-digestion (AcoD) of cow manure and corn straw was explored in this study, including cellulase pretreatment and direct additions of amylase and protease. The effects of enzymes on microbial community structure were investigated though PCR-DGGE method. Results showed that AcoD with amylase achieved the highest methane yield of 377.63 ml·CH 4 /g·VS, which was an increase of 110.79%. The methane increment consumed the amylase of 4.18 × 10 −5 g/ml·CH 4 . Enzymes mainly affected the bacteria in the hydrolysis stage rather than the bacteria in the hydrogenesis and acetogenesis stage and the archaea in the methanogenesis stage. However, the experimental results demonstrated that enzymes had no negative influence on microbial communities; the predominant microbial communities were similar. Therefore, AcoD with amylase was an effective way to improve the bio-methane yield of cow manure and corn straw. [ABSTRACT FROM AUTHOR]

Performances of batch mode solid state anaerobic digestion (SSAD) were investigated through several leachate recirculation strategies. Three parameters were shown to particularly influence methane production rates (MPR) and methane yields: the length of the interval between two recirculation events, the leachate to substrate (L:S) ratio and the volume of leachate recirculated. A central composite factor design was used to determine the influence of each parameter on methane production. Results showed that lengthening the interval between two recirculation events reduced methane yield. This effect can be counteracted by recirculating a large volume of leachate at a low L:S ratio. Steady methane production can be obtained by recirculating small amounts of leachate, and by lengthening the interval between two recirculations, regardless of the L:S ratio. However, several combinations of these parameters led to similar performances meaning that leachate recirculation practices can be modified as required by the specific constraints SSAD plants configurations. [ABSTRACT FROM AUTHOR]

The effects of oxytetracycline (OTC) on nitrogen-fixing bacterial communities were investigated during cattle manure composting. The abundance and community structure of nitrogen-fixing bacteria were determined by qPCR and denaturing gradient gel electrophoresis (DGGE), respectively. The matrix was spiked with OTC at four levels: no OTC, 10 mg/kg dry weight (DW) OTC (L), 60 mg/kg DW OTC (M), and 200 mg/kg DW OTC (H). The high temperature period of composting was shorter with M and H, and the decline in temperature during the cooling stage was accelerated by OTC. OTC had a concentration-dependent inhibitory effect on the nitrogenase activity during early composting, and the nifH gene abundance declined significantly during the later composting stage. The DGGE profile and statistical analysis showed that OTC changed the nitrogen-fixing bacterial community succession and reduced the community richness and dominance. The nitrogen-fixing bacterial community structure was affected greatly by the high level of OTC. [ABSTRACT FROM AUTHOR]

Several 60 L dry batch anaerobic digestion (AD) reactors were implemented with or without liquid reserve on cattle manure. The immersed part modulation of cattle manure increased the methane flow of about 13%. The quantitative real time PCR and the optimized DNA extraction were implemented and validated to characterize and quantify the methanogen dynamic in dry batch AD process. Final quantities of methanogens converged toward the same level in several inocula at the end of AD. Methanogen dynamic was shown by dominance of Methanosarcinaceae for acetotrophic methanogens and Methanobacteriales for the hydrogenotrophic methanogens. Overall, methanogens populations were stabilized in liquid phase, except Methanosaetaceae. Solid phase was colonized by Methanomicrobiales and Methanosarcinaceae populations giving a support to biofilm development. The methane increase could be explained by a raise of Methanosarcinaceae population in presence of a total contact between solid and liquid phases. Methanosarcinaceae was a bio-indicator of the methane production. [ABSTRACT FROM AUTHOR]