The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon(sodium bicarbonate)on anaerobic ammoni...The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon(sodium bicarbonate)on anaerobic ammonium oxidation.The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor(SBR)and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR.Research results,especially the biomass,showed first signs of anammox activity after 54 d cultivation with synthetic wast...展开更多
Microbial methanogenesis is a major source of the greenhouse gas methane(CH4).It is the final step in the anaerobic degradation of organic matter when inorganic electron acceptors such as nitrate,ferric iron,or sulfat...Microbial methanogenesis is a major source of the greenhouse gas methane(CH4).It is the final step in the anaerobic degradation of organic matter when inorganic electron acceptors such as nitrate,ferric iron,or sulfate have been depleted.Knowledge of this degradation pathway is important for the creation of mechanistic models,prediction of future CH4 emission scenarios,and development of mitigation strategies.In most anoxic environments,CH4 is produced from either acetate(aceticlastic methanogenesis)or hydrogen(H2)plus carbon dioxide(CO2)(hydrogenotrophic methanogenesis).Hydrogen can be replaced by other CO2-type methanogenesis,using formate,carbon monoxide(CO),or alcohols as substrates.The ratio of these two pathways is tightly constrained by the stoichiometry of conversion processes.If the degradation of organic matter is complete(e.g.,degradation of straw in rice paddies),then fermentation eventually results in production of acetate and H2 at a ratio of>67%aceticlastic and<33%hydrogenotrophic methanogensis.However,acetate production can be favored when heterotrophic or chemolithotrophic acetogenesis is enhanced,and H2 production can be favored when syntrophic acetate oxidation is enhanced.This typically occurs at low and elevated temperatures,respectively.Thus,temperature can strongly influence the methanogenic pathway,which may range from 100%aceticlastic methanogenesis at low temperatures to 100%hydrogenotrophic methanogenesis at high temperatures.However,if the degradation of organic matter is not complete(e.g.,degradation of soil organic matter),the stoichiometry of fermentation is not tightly constrained,resulting,for example,in the preferential production of H2,followed by hydrogenotrophic methanogenesis.Preferential production of CH4 by either aceticlastic or hydrogenotrophic methanogenesis can also happen if one of the methanogenic substrates is not consumed by methanogens but is,instead,accumulated,volatilized,or utilized otherwise.Methylotrophic methanogens,which can use methanol as a substrate,are w展开更多
Coke plant effluents with high contents of organic compounds are mainly treated by biological aerobic fermentation after physical pre-treatment. In this study, a brown coal condensate wastewater from a low temperature...Coke plant effluents with high contents of organic compounds are mainly treated by biological aerobic fermentation after physical pre-treatment. In this study, a brown coal condensate wastewater from a low temperature coking process was fermented under methanogenic conditions in discontinuous experiments. By this fermentation, acetate, propionate, and the main polyphenolic compounds （catechol, resorcinol and hydroquinone） were degraded to a level below the detection limit. The COD was reduced by 72% with a residual concentration of 2.1 g/L. This anaerobic fermented wastewater had a residual BOD5 of 0.66 g/L and 2.2 L CH4 were formed per litre of wastewater. An abiotic pre-treatment for this wastewater with air had a negative effect on the COD reduction and decrease of colour on the methanogenic fermentation due to the autoxidation of polyphenolic compounds to humic-like compounds. This study showed that methanogenic fermentations in the treatment sequence of brown coal coking wastewaters could reduce energy consumption for aeration in further treatment processes and had the potential for a better effluent quality due to a less formation of recalcitrant humic-like compounds.展开更多
Global warming, as a result of an increase in the mean temperature of the planet, might lead to catastrophic events for humanity. This temperature increase is mainly the result of an increase in the atmospheric greenh...Global warming, as a result of an increase in the mean temperature of the planet, might lead to catastrophic events for humanity. This temperature increase is mainly the result of an increase in the atmospheric greenhouse gases （GHG） concentration. Water vapor, carbon dioxide （CO2）, methane （CH4） and nitrous oxide （N20） are the most important GHG, and human activities, such as industry, livestock and agriculture, contribute to the production of these gases. Methane, at an atmospheric concentration of 1.7 gmol tool-1 currently, is responsible for 16% of the global warming due to its relatively high global warming potential. Soils play an important role in the CH4 cycle as methanotrophy （oxidation of CH4） and methanogenesis （production of CH4） take place in them. Understanding methanogenesis and methanotrophy is essential to establish new agriculture techniques and industrial processes that contribute to a better balance of GHG. The current knowledge of methanogenesis and methanotrophy in soils, anaerobic CH4 oxidation and methanotrophy in extreme environments is also discussed.展开更多
The concept of temperature staged and biological phased （TSBP） was proposed to enhance the performance of waste-activated sludge anaerobic digestion. Semi-continuous experiments were used to investigate the effect o...The concept of temperature staged and biological phased （TSBP） was proposed to enhance the performance of waste-activated sludge anaerobic digestion. Semi-continuous experiments were used to investigate the effect of temperature （35 to 70℃） as well as the hydraulic retention time （HRT） （2, 4 and 6 days） on the acidogenic phase. The results showed that the solubilization degree of waste- activated sludge increased from 14.7% to 30.1% with temperature increasing from 35 to 70℃, while the acidification degree was highest at 45℃ （17.6%）, and this was quite different from the temperature impact on hydrolysis. Compared with HRT of 2 and 6 days, 4 days was chosen as the appropriate HRT because of its relatively high solubilization degree （24.6%） and acidification degree （20.1%） at 45℃. The TSBP system combined the acidogenic reactor （45℃, 4 days） with the methanogenic reactor （35℃, 16 days） and the results showed 84.8% and 11.4% higher methane yield and volatile solid reduction, respectively, compared with that of the single-stage anaerobic digestion system with HRT of 20 days at 35℃. Moreover, different microbial morphologies were observed in the acidogenic- and methanogenic-phase reactors, which resulted from the temperature control and HRT adjustment. All the above results indicated that 45℃ was the optimum temperature to inhibit the activity of methanogenic bacteria in the acidogenic phase, and temperature staging and phase separation was thus accomplished. The advantages of the TSBP process were also confirmed by a full-scale waste-activated sludge anaerobic digestion project which was an energy self-sufficient system.展开更多
The objective of the present study was to examine the effect of different weaning methods on the ruminal methanogenic archaea composition and diversity in Holstein calves.Thirty-six newborn Holstein bull calves were a...The objective of the present study was to examine the effect of different weaning methods on the ruminal methanogenic archaea composition and diversity in Holstein calves.Thirty-six newborn Holstein bull calves were assigned to 1 of 3 treatments:(1)conventional weaning(d 56)and fed a high proportion of solid feed(CWS);(2)conventional weaning(d 56)and fed a high proportion of liquid feed(CWL);(3)early weaning(d 42)and fed with a high proportion of solid feed(EWS).High-throughput sequencing of the methyl coenzyme M reductase(mcr A)gene,which encodes theα-subunit of methyl coenzyme M reductase-the enzyme that catalyzes the final step in methanogenesis was used to determine the composition and diversity of rumen methanogens.No significant difference(P>0.05)was observed for operational taxonomic units(OTUs)or richness indices,but diversity indices increased(P<0.05)for calves fed high dietary solids.Predominant families across the three treatments were Methanobacteriaceae,Thermoplasmataceae and Methanomassiliicoccaceae.Calves in the EWS treatment had a higher(P<0.05)relative abundance of Methanobrevibacter sp.strain AbM4 and Methanosphaera stadtmanae,while calves in the CWL treatment had a higher(P<0.05)abundance of Methanosphaera sp.strain SM9.A positive(P<0.05)relationship was identified between butyrate and Methanobrevibacter sp.strain AbM4.In conclusion,the composition and diversity of methanogens in the rumen of Holstein calves varied under the different weaning methods.This study identified a positive relationship between butyrate and Methanobrevibacter sp.strain AbM4,potentially reflecting correlations between ruminal fermentation variables and methanogenesis function.These in-depth analyses provide further understanding of weaning methods for intensified production systems.展开更多
A lab-scale continuously-stirred tank reactor （CSTR）, used for anaerobic co-digestion of fruit and vegetable waste （FVW） and food waste （FW） at different mixture ratios, was operated for 178 days at the organic ...A lab-scale continuously-stirred tank reactor （CSTR）, used for anaerobic co-digestion of fruit and vegetable waste （FVW） and food waste （FW） at different mixture ratios, was operated for 178 days at the organic loading rate of 3 kg VS （volatile solids）/（m3.day）. The dynamics of the Archaeal community and the correlations between environmental variables and methanogenic community structure were analyzed by polymerase chain reactions - denaturing gradient gel electrophoresis （PCR-DGGE） and redundancy analysis （RDA）, respectively. PCR-DGGE results demonstrated that the mixture ratio of FVW to FW altered the community composition of Archaea. As the FVW]FW ratio increased, Methanoculleus, Methanosaeta and Methanosarcina became the predominant methanogens in the community. Redundancy analysis results indicated that the shift of the methanogenic community was significantly correlated with the composition of acidogenic products and methane production yield. Different mixture ratios of substrates led to different compositions of intermediate metabolites, which may affect the methanogenic community. These results suggested that the analysis of microbial communities could be used to diagnose anaerobic processes.展开更多
Anaerobic digestion(AD)of organic fraction of municipal solid waste(OFMSW)is prone to system breakdown under high organic loading rates(OLRs)condition,which subsequently reduces the efficiency of digestion process and...Anaerobic digestion(AD)of organic fraction of municipal solid waste(OFMSW)is prone to system breakdown under high organic loading rates(OLRs)condition,which subsequently reduces the efficiency of digestion process and results in substantial economic losses.In this perspective paper,the substances metabolisms,electrons flow,as well as microbial interaction mechanisms within AD process are comprehensively discussed,and the underlying bottleneck that causes inefficient methane production is identified,which is“electrons surplus”.Systems encountering severe electron surplus are at risk of process failure,making it crucial to proactively prevent this phenomenon through appropriate approaches.On this basis,the present perspective proposes three potential electronic regulation strategies to prevent electrons surplus,namely,electron shunt,accelerating electron transfer and regulating methanogenic metabolism pathway,and presents specific methodologies for each strategy.Furthermore,the potential solutions to challenges that may occur during the electronic regulation process are also presented in this paper.This perspective aims to provide innovative approaches to achieve the efficient and stable operation of OFMSW anaerobic digestion,especially under high OLRs condition.展开更多
Little is known about the stable carbon isotopes of methane （CH4） emitted （δ13CH4elnitted） from permanently flooded rice fields and double rice-cropping fields. The CH4 emission and corresponding （δ13CH4emitted...Little is known about the stable carbon isotopes of methane （CH4） emitted （δ13CH4elnitted） from permanently flooded rice fields and double rice-cropping fields. The CH4 emission and corresponding （δ13CH4emitted under various field managements （mulching, water regime, tillage, and nitrogen （N） fertilization） were simultaneously measured in three typical Chinese rice fields, a permanently flooded rice field in Ziyang City, Sichuan Province, Southwest China, a double-rice cropping field in Yingtan City, Jiangxi Province, Southeast China, and a rice-wheat rotation field in Jurong City, Jiangsu Province, East China, from 2010 to 2012. Results showed different seasonal variations of δ13CH4emitted among the three fields during the rice-growing season. The values of （δ13CH4emitted were negatively correlated with corresponding CH4 emissions in seasonal variation and mean, indicating the importance of CH4 production, oxidation, and transport associated with isotopic fractionation effects to the δ13CH4emitted. Seasonal variations of δ13CH4emltted were slightly impacted by mulching cultivation, tillage, and N application, but highly controlled by drainage. Meanwhile, tillage, N application, and especially mulching cultivation had important effects on seasonal mean CH4 emissions and corresponding δ13CH4emitted with low emissions accompanied by high values of δ13CH4emitted. Seasonal mean values of （δ13CH4emitted from the three fields were similar, mostly ranging from -60‰ to -50‰ which are well in agreement with previously published data. These demonstrated that seasonal variations of （δ13CH4emitted mainly depended on the changes in CH4 emission from rice fields and further indicated the important effects of methanogenic pathways, CH4 oxidation, and CH4 transport associated with isotope fractionation effects influenced by field managements on δ13CH4emitted.展开更多
A series of batch experiments were conducted in 125 mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflo...A series of batch experiments were conducted in 125 mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflow anaerobic sludge bed（UASB） and expanded granular sludge bed（EGSB） reactors. The effects of pH value and temperature on toxicity of ammonia nitrogen to anaerobes were investigated. The results show that the specific methanogenic activity of anaerobic granular sludge suffers inhibition from ammonia nitrogen, the concentrations of ammonia nitrogen that produce 50 % inhibition of specific methanogenic activity for sludge from UASB and EGSB reactor are 2.35 and 2.75 g/L, respectively. Hydrogen utilizing methanogens suffers less inhibition from ammonia mtrogen than that of acetate utilizing methanogens. Hydrogen-producing acetogens that utilize propionate and butyrate as substrates suffer serious inhibition from ammonia nitrogen. The toxicity of ammonia nitrogen to anaerobic granular sludge enhances when pH value and temperature increase. Anaerobic granular sludge can bear higher concentrations of ammonia nitrogen after being acclimated by ammonia nitrogen for 7 d.展开更多
Microplastics and nanoplastics are emerging pollutants that substantially influence biological element cycling in natural ecosystems.Plastics are also prevalent in sewage,and they accumulate in waste-activated sludge(...Microplastics and nanoplastics are emerging pollutants that substantially influence biological element cycling in natural ecosystems.Plastics are also prevalent in sewage,and they accumulate in waste-activated sludge(WAS).However,the impacts of plastics on the methanogenic digestion of WAS and the underpinning microbiome remain underexplored,particularly during long-term operation.In this study,we found that short-term exposure to individual microplastics and nanoplastics(polyethylene,polyvinyl chloride,polystyrene,and polylactic acid)at a low concentration(10 particles/g sludge)slightly enhanced methanogenesis by 2.1%−9.0%,whereas higher levels(30−200 particles/g sludge)suppressed methanogenesis by 15.2%−30.1%.Notably,the coexistence of multiple plastics,particularly at low concentrations,showed synergistic suppression of methanogenesis.Unexpectedly,methanogenesis activity completely recovered after long-term exposure to plastics,despite obvious suppression of methanogenesis by initial plastic exposure.The inhibition of methanogenesis by plastics could be attributed to the stimulated generation of reactive oxygen species.The stress induced by plastics dramatically decreased the relative abundance of methanogens but showed marginal influence on putative hydrolytic and fermentation populations.Nonetheless,the digestion sludge microbiome exhibited resilience and functional redundancy,contributing to the recovery of methanogenesis during the long-term operation of digesters.Plastics also increased the complexity,modularity,and negative interaction ratios of digestion sludge microbiome networks,but their influence on community assembly varied.Interestingly,a unique plastisphere was observed,the networks and assembly of which were distinct from the sludge microbiome.Collectively,the comprehensive evaluation of the influence of microplastics and nanoplastics on methanogenic digestion,together with the novel ecological insights,contribute to better understanding and manipulating this engineered ecosystem in the fa展开更多
The community structure of methanogenic archaea is relatively stable,i.e.,it is sustained at a high abundance with minimal changes in composition,in paddy field soils irrespective of submergence and drainage.In contra...The community structure of methanogenic archaea is relatively stable,i.e.,it is sustained at a high abundance with minimal changes in composition,in paddy field soils irrespective of submergence and drainage.In contrast,the abundance in non-methanogenic oxic soils is much lower than that in paddy field soils.This study aimed to describe methanogenic archaeal community development following the long-term submergence of non-methanogenic oxic upland field soils in pot and field experiments.In the pot experiment,a soil sample obtained from an upland field was incubated under submerged conditions for 275 d.Soil samples periodically collected were subjected to culture-dependent most probable number(MPN)enumeration,polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)analysis of archaeal 16 S r RNA gene,and quantitative PCR analysis of the methyl-coenzyme M reductase alpha subunit gene(mcr A)of methanogenic archaea.The abundance of methanogenic archaea increased from 102 to 103 cells g-1 dry soil and 104 to 107 copies of mcr A gene g-1 dry soil after submergence.Although no methanogenic archaeon was detected prior to incubation by the DGGE analysis,members from Methanocellales,Methanosarcinaceae,and Methanosaetaceae proliferated in the soils,and the community structure was relatively stable once established.In the field experiment,the number of viable methanogenic archaea in a rice paddy field converted from meadow(reclaimed paddy field)was monitored by MPN enumeration over five annual cycles of field operations.Viability was also determined simultaneously in a paddy field where the plow layer soil from a farmer’s paddy field was dressed onto the meadow(dressed paddy field)and an upland crop field converted from the meadow(reclaimed upland field).The number of viable methanogenic archaea in the reclaimed paddy field was below the detection limit before the first cultivation of rice and in the reclaimed upland field.Then,the number gradually increased over five years and finally reached 103–104 展开更多
Bioreactor landfills allow a more active landfill management that recognizes the biological, chemical and physical processes involved in a landfill environment. The laboratory-scale simulators of landfill reactors tre...Bioreactor landfills allow a more active landfill management that recognizes the biological, chemical and physical processes involved in a landfill environment. The laboratory-scale simulators of landfill reactors treating municipal solid wastes were studied, the effect of solid waste size, leachate recirculation, nutrient balance, pH value, moisture content and temperature on the rate of municipal solid waste(MSW) biodegradation were determined, and it indicated the optimum pH value, moisture content and temperature decomposing MSW. The results of waste biodegradation were compared with that of the leachate-recirculated landfill simulator and conservative sanitary landfill simulator. In the control experiment the antitheses of a decreasing trend of the organic load, measured as biological oxygen demand and chemical oxygen demand, was shown. An obvious enhancement of effective disposal from conservative sanitary landfill(CSL) simulator, to the leachate-recirculated landfill(LRL) simulator and to the conditioned bioreactor landfill(CBL) simulator would be noted, through displaying the compared results of solid waste settlement, heavy metal concentration in leachate, methane production rate, biogas composition, BOD and COD as well as their ratio.展开更多
The maximum specific methanogenic activity （SMA） of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading ba...The maximum specific methanogenic activity （SMA） of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/（g VSS.d） when biomass was in contact with sulfate at a ratio of 1：0.114 by weight.展开更多
Rapid formation of autotrophic partial denitrification(APD)granules is of practical interest to start up an expanded granular sludge bed reactor for wastewater treatment.This study demonstrates that methanogenic granu...Rapid formation of autotrophic partial denitrification(APD)granules is of practical interest to start up an expanded granular sludge bed reactor for wastewater treatment.This study demonstrates that methanogenic granules can be easily acclimated into autotrophic partial denitrification granules in one day,with the ability to remove 82%of 2.7 kg-S/(m^3·d)sulfide into S^0 and to convert 97%of 0.9 kg-N/(m^3·d)nitrate into nitrite,which can provide a promising feedstock for anaerobic ammonia oxidation process.Arcobacter sp.is essential for S^0 accumulation.Under high loadings,the abundance of Arcobacter sp.decreased,while on the contrary the abundance of unclassified_p_Firmicutes increased,leading to the deterioration of autotrophic partial denitrification performance.The granules performance could be recovered by adopting the strategies of properly reducing the influent loadings.展开更多
文摘The present lab-scale research reveals the enrichment of anaerobic ammonium oxidation microorganism from methanogenic anaerobic granular sludge and the effect of inorganic carbon(sodium bicarbonate)on anaerobic ammonium oxidation.The enrichment of anammox bacteria was carried out in a 7.0-L sequencing batch reactor(SBR)and the effect of bicarbonate on anammox was conducted in a 3.0-L SBR.Research results,especially the biomass,showed first signs of anammox activity after 54 d cultivation with synthetic wast...
基金the Fonds der Chemischen Industrie (Fonds of the Chemical Industry), Germany.
文摘Microbial methanogenesis is a major source of the greenhouse gas methane(CH4).It is the final step in the anaerobic degradation of organic matter when inorganic electron acceptors such as nitrate,ferric iron,or sulfate have been depleted.Knowledge of this degradation pathway is important for the creation of mechanistic models,prediction of future CH4 emission scenarios,and development of mitigation strategies.In most anoxic environments,CH4 is produced from either acetate(aceticlastic methanogenesis)or hydrogen(H2)plus carbon dioxide(CO2)(hydrogenotrophic methanogenesis).Hydrogen can be replaced by other CO2-type methanogenesis,using formate,carbon monoxide(CO),or alcohols as substrates.The ratio of these two pathways is tightly constrained by the stoichiometry of conversion processes.If the degradation of organic matter is complete(e.g.,degradation of straw in rice paddies),then fermentation eventually results in production of acetate and H2 at a ratio of>67%aceticlastic and<33%hydrogenotrophic methanogensis.However,acetate production can be favored when heterotrophic or chemolithotrophic acetogenesis is enhanced,and H2 production can be favored when syntrophic acetate oxidation is enhanced.This typically occurs at low and elevated temperatures,respectively.Thus,temperature can strongly influence the methanogenic pathway,which may range from 100%aceticlastic methanogenesis at low temperatures to 100%hydrogenotrophic methanogenesis at high temperatures.However,if the degradation of organic matter is not complete(e.g.,degradation of soil organic matter),the stoichiometry of fermentation is not tightly constrained,resulting,for example,in the preferential production of H2,followed by hydrogenotrophic methanogenesis.Preferential production of CH4 by either aceticlastic or hydrogenotrophic methanogenesis can also happen if one of the methanogenic substrates is not consumed by methanogens but is,instead,accumulated,volatilized,or utilized otherwise.Methylotrophic methanogens,which can use methanol as a substrate,are w
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT0853)
文摘Coke plant effluents with high contents of organic compounds are mainly treated by biological aerobic fermentation after physical pre-treatment. In this study, a brown coal condensate wastewater from a low temperature coking process was fermented under methanogenic conditions in discontinuous experiments. By this fermentation, acetate, propionate, and the main polyphenolic compounds （catechol, resorcinol and hydroquinone） were degraded to a level below the detection limit. The COD was reduced by 72% with a residual concentration of 2.1 g/L. This anaerobic fermented wastewater had a residual BOD5 of 0.66 g/L and 2.2 L CH4 were formed per litre of wastewater. An abiotic pre-treatment for this wastewater with air had a negative effect on the COD reduction and decrease of colour on the methanogenic fermentation due to the autoxidation of polyphenolic compounds to humic-like compounds. This study showed that methanogenic fermentations in the treatment sequence of brown coal coking wastewaters could reduce energy consumption for aeration in further treatment processes and had the potential for a better effluent quality due to a less formation of recalcitrant humic-like compounds.
基金Supported by the Centro de Investigación y de Estudios Avanzados del IPN,Mexico and the Consejo Nacional de Ciencia y Tecnología,Mexico(Nos.153216,232468 and 245119)
文摘Global warming, as a result of an increase in the mean temperature of the planet, might lead to catastrophic events for humanity. This temperature increase is mainly the result of an increase in the atmospheric greenhouse gases （GHG） concentration. Water vapor, carbon dioxide （CO2）, methane （CH4） and nitrous oxide （N20） are the most important GHG, and human activities, such as industry, livestock and agriculture, contribute to the production of these gases. Methane, at an atmospheric concentration of 1.7 gmol tool-1 currently, is responsible for 16% of the global warming due to its relatively high global warming potential. Soils play an important role in the CH4 cycle as methanotrophy （oxidation of CH4） and methanogenesis （production of CH4） take place in them. Understanding methanogenesis and methanotrophy is essential to establish new agriculture techniques and industrial processes that contribute to a better balance of GHG. The current knowledge of methanogenesis and methanotrophy in soils, anaerobic CH4 oxidation and methanotrophy in extreme environments is also discussed.
基金supported by the National Hi-Tech Research and Development Program (863) of China (No.2009AA064702,2011AA060901)
文摘The concept of temperature staged and biological phased （TSBP） was proposed to enhance the performance of waste-activated sludge anaerobic digestion. Semi-continuous experiments were used to investigate the effect of temperature （35 to 70℃） as well as the hydraulic retention time （HRT） （2, 4 and 6 days） on the acidogenic phase. The results showed that the solubilization degree of waste- activated sludge increased from 14.7% to 30.1% with temperature increasing from 35 to 70℃, while the acidification degree was highest at 45℃ （17.6%）, and this was quite different from the temperature impact on hydrolysis. Compared with HRT of 2 and 6 days, 4 days was chosen as the appropriate HRT because of its relatively high solubilization degree （24.6%） and acidification degree （20.1%） at 45℃. The TSBP system combined the acidogenic reactor （45℃, 4 days） with the methanogenic reactor （35℃, 16 days） and the results showed 84.8% and 11.4% higher methane yield and volatile solid reduction, respectively, compared with that of the single-stage anaerobic digestion system with HRT of 20 days at 35℃. Moreover, different microbial morphologies were observed in the acidogenic- and methanogenic-phase reactors, which resulted from the temperature control and HRT adjustment. All the above results indicated that 45℃ was the optimum temperature to inhibit the activity of methanogenic bacteria in the acidogenic phase, and temperature staging and phase separation was thus accomplished. The advantages of the TSBP process were also confirmed by a full-scale waste-activated sludge anaerobic digestion project which was an energy self-sufficient system.
基金supported by the Key Program for International S&T Cooperation Projects of China(2016YFE0109000)the National Key R&D Program of China(2017YFF0211702)+1 种基金the National Natural Science Foundation of China(41475126 and 31802085)the Young Scientist Lifting Project,China(2017–2019)
文摘The objective of the present study was to examine the effect of different weaning methods on the ruminal methanogenic archaea composition and diversity in Holstein calves.Thirty-six newborn Holstein bull calves were assigned to 1 of 3 treatments:(1)conventional weaning(d 56)and fed a high proportion of solid feed(CWS);(2)conventional weaning(d 56)and fed a high proportion of liquid feed(CWL);(3)early weaning(d 42)and fed with a high proportion of solid feed(EWS).High-throughput sequencing of the methyl coenzyme M reductase(mcr A)gene,which encodes theα-subunit of methyl coenzyme M reductase-the enzyme that catalyzes the final step in methanogenesis was used to determine the composition and diversity of rumen methanogens.No significant difference(P>0.05)was observed for operational taxonomic units(OTUs)or richness indices,but diversity indices increased(P<0.05)for calves fed high dietary solids.Predominant families across the three treatments were Methanobacteriaceae,Thermoplasmataceae and Methanomassiliicoccaceae.Calves in the EWS treatment had a higher(P<0.05)relative abundance of Methanobrevibacter sp.strain AbM4 and Methanosphaera stadtmanae,while calves in the CWL treatment had a higher(P<0.05)abundance of Methanosphaera sp.strain SM9.A positive(P<0.05)relationship was identified between butyrate and Methanobrevibacter sp.strain AbM4.In conclusion,the composition and diversity of methanogens in the rumen of Holstein calves varied under the different weaning methods.This study identified a positive relationship between butyrate and Methanobrevibacter sp.strain AbM4,potentially reflecting correlations between ruminal fermentation variables and methanogenesis function.These in-depth analyses provide further understanding of weaning methods for intensified production systems.
基金supported by the Ministry of Science and Technology of China(No.2008BADC4B16,2008BADC4B18,2008AA062401)
文摘A lab-scale continuously-stirred tank reactor （CSTR）, used for anaerobic co-digestion of fruit and vegetable waste （FVW） and food waste （FW） at different mixture ratios, was operated for 178 days at the organic loading rate of 3 kg VS （volatile solids）/（m3.day）. The dynamics of the Archaeal community and the correlations between environmental variables and methanogenic community structure were analyzed by polymerase chain reactions - denaturing gradient gel electrophoresis （PCR-DGGE） and redundancy analysis （RDA）, respectively. PCR-DGGE results demonstrated that the mixture ratio of FVW to FW altered the community composition of Archaea. As the FVW]FW ratio increased, Methanoculleus, Methanosaeta and Methanosarcina became the predominant methanogens in the community. Redundancy analysis results indicated that the shift of the methanogenic community was significantly correlated with the composition of acidogenic products and methane production yield. Different mixture ratios of substrates led to different compositions of intermediate metabolites, which may affect the methanogenic community. These results suggested that the analysis of microbial communities could be used to diagnose anaerobic processes.
基金the financial support for this work provided by the National Natural Science Point Foundation of China(No.52131002)the International Exchange Program for Graduate Students,Tongji University(China)(No.2023020014).
文摘Anaerobic digestion(AD)of organic fraction of municipal solid waste(OFMSW)is prone to system breakdown under high organic loading rates(OLRs)condition,which subsequently reduces the efficiency of digestion process and results in substantial economic losses.In this perspective paper,the substances metabolisms,electrons flow,as well as microbial interaction mechanisms within AD process are comprehensively discussed,and the underlying bottleneck that causes inefficient methane production is identified,which is“electrons surplus”.Systems encountering severe electron surplus are at risk of process failure,making it crucial to proactively prevent this phenomenon through appropriate approaches.On this basis,the present perspective proposes three potential electronic regulation strategies to prevent electrons surplus,namely,electron shunt,accelerating electron transfer and regulating methanogenic metabolism pathway,and presents specific methodologies for each strategy.Furthermore,the potential solutions to challenges that may occur during the electronic regulation process are also presented in this paper.This perspective aims to provide innovative approaches to achieve the efficient and stable operation of OFMSW anaerobic digestion,especially under high OLRs condition.
基金financially supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB15020103)the National Key Technology Research and Development Program of China(No.2013BAD11B02)+2 种基金the National Natural Sciences Foundation of China(Nos.41571232 and 41271259)the State Key Laboratory of Soil and Sustainable Agriculture(No.Y412010003)the Knowledge Innovation Program of Institute of Soil Science,Chinese Academy of Sciences(No.ISSASIP1654)
文摘Little is known about the stable carbon isotopes of methane （CH4） emitted （δ13CH4elnitted） from permanently flooded rice fields and double rice-cropping fields. The CH4 emission and corresponding （δ13CH4emitted under various field managements （mulching, water regime, tillage, and nitrogen （N） fertilization） were simultaneously measured in three typical Chinese rice fields, a permanently flooded rice field in Ziyang City, Sichuan Province, Southwest China, a double-rice cropping field in Yingtan City, Jiangxi Province, Southeast China, and a rice-wheat rotation field in Jurong City, Jiangsu Province, East China, from 2010 to 2012. Results showed different seasonal variations of δ13CH4emitted among the three fields during the rice-growing season. The values of （δ13CH4emitted were negatively correlated with corresponding CH4 emissions in seasonal variation and mean, indicating the importance of CH4 production, oxidation, and transport associated with isotopic fractionation effects to the δ13CH4emitted. Seasonal variations of δ13CH4emltted were slightly impacted by mulching cultivation, tillage, and N application, but highly controlled by drainage. Meanwhile, tillage, N application, and especially mulching cultivation had important effects on seasonal mean CH4 emissions and corresponding δ13CH4emitted with low emissions accompanied by high values of δ13CH4emitted. Seasonal mean values of （δ13CH4emitted from the three fields were similar, mostly ranging from -60‰ to -50‰ which are well in agreement with previously published data. These demonstrated that seasonal variations of （δ13CH4emitted mainly depended on the changes in CH4 emission from rice fields and further indicated the important effects of methanogenic pathways, CH4 oxidation, and CH4 transport associated with isotope fractionation effects influenced by field managements on δ13CH4emitted.
文摘A series of batch experiments were conducted in 125 mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflow anaerobic sludge bed（UASB） and expanded granular sludge bed（EGSB） reactors. The effects of pH value and temperature on toxicity of ammonia nitrogen to anaerobes were investigated. The results show that the specific methanogenic activity of anaerobic granular sludge suffers inhibition from ammonia nitrogen, the concentrations of ammonia nitrogen that produce 50 % inhibition of specific methanogenic activity for sludge from UASB and EGSB reactor are 2.35 and 2.75 g/L, respectively. Hydrogen utilizing methanogens suffers less inhibition from ammonia mtrogen than that of acetate utilizing methanogens. Hydrogen-producing acetogens that utilize propionate and butyrate as substrates suffer serious inhibition from ammonia nitrogen. The toxicity of ammonia nitrogen to anaerobic granular sludge enhances when pH value and temperature increase. Anaerobic granular sludge can bear higher concentrations of ammonia nitrogen after being acclimated by ammonia nitrogen for 7 d.
基金supported by the Ministry of Education,Singapore,under Academic Research Fund Tier 2 under project No.:MOE-000033-01Tier 1 under Project No.:R-302-000-239-114。
文摘Microplastics and nanoplastics are emerging pollutants that substantially influence biological element cycling in natural ecosystems.Plastics are also prevalent in sewage,and they accumulate in waste-activated sludge(WAS).However,the impacts of plastics on the methanogenic digestion of WAS and the underpinning microbiome remain underexplored,particularly during long-term operation.In this study,we found that short-term exposure to individual microplastics and nanoplastics(polyethylene,polyvinyl chloride,polystyrene,and polylactic acid)at a low concentration(10 particles/g sludge)slightly enhanced methanogenesis by 2.1%−9.0%,whereas higher levels(30−200 particles/g sludge)suppressed methanogenesis by 15.2%−30.1%.Notably,the coexistence of multiple plastics,particularly at low concentrations,showed synergistic suppression of methanogenesis.Unexpectedly,methanogenesis activity completely recovered after long-term exposure to plastics,despite obvious suppression of methanogenesis by initial plastic exposure.The inhibition of methanogenesis by plastics could be attributed to the stimulated generation of reactive oxygen species.The stress induced by plastics dramatically decreased the relative abundance of methanogens but showed marginal influence on putative hydrolytic and fermentation populations.Nonetheless,the digestion sludge microbiome exhibited resilience and functional redundancy,contributing to the recovery of methanogenesis during the long-term operation of digesters.Plastics also increased the complexity,modularity,and negative interaction ratios of digestion sludge microbiome networks,but their influence on community assembly varied.Interestingly,a unique plastisphere was observed,the networks and assembly of which were distinct from the sludge microbiome.Collectively,the comprehensive evaluation of the influence of microplastics and nanoplastics on methanogenic digestion,together with the novel ecological insights,contribute to better understanding and manipulating this engineered ecosystem in the fa
基金a Grant-in-Aid for Japan Society for the Promotion of Science (JSPS) Fellows (No. 19 6611)JSPS KAKENHI (No. 24780318).
文摘The community structure of methanogenic archaea is relatively stable,i.e.,it is sustained at a high abundance with minimal changes in composition,in paddy field soils irrespective of submergence and drainage.In contrast,the abundance in non-methanogenic oxic soils is much lower than that in paddy field soils.This study aimed to describe methanogenic archaeal community development following the long-term submergence of non-methanogenic oxic upland field soils in pot and field experiments.In the pot experiment,a soil sample obtained from an upland field was incubated under submerged conditions for 275 d.Soil samples periodically collected were subjected to culture-dependent most probable number(MPN)enumeration,polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)analysis of archaeal 16 S r RNA gene,and quantitative PCR analysis of the methyl-coenzyme M reductase alpha subunit gene(mcr A)of methanogenic archaea.The abundance of methanogenic archaea increased from 102 to 103 cells g-1 dry soil and 104 to 107 copies of mcr A gene g-1 dry soil after submergence.Although no methanogenic archaeon was detected prior to incubation by the DGGE analysis,members from Methanocellales,Methanosarcinaceae,and Methanosaetaceae proliferated in the soils,and the community structure was relatively stable once established.In the field experiment,the number of viable methanogenic archaea in a rice paddy field converted from meadow(reclaimed paddy field)was monitored by MPN enumeration over five annual cycles of field operations.Viability was also determined simultaneously in a paddy field where the plow layer soil from a farmer’s paddy field was dressed onto the meadow(dressed paddy field)and an upland crop field converted from the meadow(reclaimed upland field).The number of viable methanogenic archaea in the reclaimed paddy field was below the detection limit before the first cultivation of rice and in the reclaimed upland field.Then,the number gradually increased over five years and finally reached 103–104
文摘Bioreactor landfills allow a more active landfill management that recognizes the biological, chemical and physical processes involved in a landfill environment. The laboratory-scale simulators of landfill reactors treating municipal solid wastes were studied, the effect of solid waste size, leachate recirculation, nutrient balance, pH value, moisture content and temperature on the rate of municipal solid waste(MSW) biodegradation were determined, and it indicated the optimum pH value, moisture content and temperature decomposing MSW. The results of waste biodegradation were compared with that of the leachate-recirculated landfill simulator and conservative sanitary landfill simulator. In the control experiment the antitheses of a decreasing trend of the organic load, measured as biological oxygen demand and chemical oxygen demand, was shown. An obvious enhancement of effective disposal from conservative sanitary landfill(CSL) simulator, to the leachate-recirculated landfill(LRL) simulator and to the conditioned bioreactor landfill(CBL) simulator would be noted, through displaying the compared results of solid waste settlement, heavy metal concentration in leachate, methane production rate, biogas composition, BOD and COD as well as their ratio.
基金Project supported by the National Research Center of Environmental and Hazardous Waste Management(NRC-EHWM), Chulalongko1 University,Thailand.
文摘The maximum specific methanogenic activity （SMA） of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/（g VSS.d） when biomass was in contact with sulfate at a ratio of 1：0.114 by weight.
基金supported by the National Natural Science Foundation of China (21307160)the Natural Science Foundation of Shandong Province, China (ZR20192019MEE038)+3 种基金the Fundamental Research Funds for the Central Universities (19CX02038A)the Open Project of Key Laboratory of Environmental Biotechnology, CAS (Grant No. kf2018003)the Open Project Program of State Key Laboratory of Petroleum Pollution Control (Grant No. PPC2018006)the CNPC Research Institute of Safety and Environmental Technology
文摘Rapid formation of autotrophic partial denitrification(APD)granules is of practical interest to start up an expanded granular sludge bed reactor for wastewater treatment.This study demonstrates that methanogenic granules can be easily acclimated into autotrophic partial denitrification granules in one day,with the ability to remove 82%of 2.7 kg-S/(m^3·d)sulfide into S^0 and to convert 97%of 0.9 kg-N/(m^3·d)nitrate into nitrite,which can provide a promising feedstock for anaerobic ammonia oxidation process.Arcobacter sp.is essential for S^0 accumulation.Under high loadings,the abundance of Arcobacter sp.decreased,while on the contrary the abundance of unclassified_p_Firmicutes increased,leading to the deterioration of autotrophic partial denitrification performance.The granules performance could be recovered by adopting the strategies of properly reducing the influent loadings.
