Composting is a suitable low-cost strategy to transform animal waste into a stabilized end product,and the airflow field in the pile affects the fermentation states.For piles in the aeration weak zone,anaerobic fermen...Composting is a suitable low-cost strategy to transform animal waste into a stabilized end product,and the airflow field in the pile affects the fermentation states.For piles in the aeration weak zone,anaerobic fermentation may happen as the lack of oxygen.While in practice,due to the extremely low speed and harsh condition,the airflow field was scarcely researched.This study adopted Computational Fluid Dynamics(CFD)to investigate the airflow field in the compost pile.A three-dimensional CFD model was built;the compost pile in this model was simplified as porous media;unstructured mesh was adopted to discretize the geometric model;standard k-εmodel and SIMPLE scheme were employed for numerical methods.The CFD model was validated with the field experiment in the cooling period.Then the model was applied to research the airflow field in the pile with increased pipe diameter.Results showed that it was feasible to investigate the airflow field in the pile with CFD.For boundary conditions in the CFD model,treating the compost pile as a homogeneous porous media is reasonable.The CFD model was successfully validated by the field measurement(the average relative difference between the simulated and measured air speed was within 10%).Airflow in the existing compost pile showed nonuniform distribution with stagnation and vortex zones;the turbulence intensities were 3.57 and 1.43 for the airflow in the pile and the reactor,respectively.When pipe diameter increased,the airflow distribution uniformity in the pile was improved significantly.With diameter raising to 0.04 m,the turbulence intensity decreased to 1.54 and 0.42 for the airflow in the pile and the reactor,respectively.The CFD model developed in this research can provide qualitative and quantitative analyses of the airflow field in compost piles,and can be a theoretical basis for the aeration system design.展开更多
Elimination of antibiotic resistance genes(ARGs)in animal manure from concentrated animal feeding operations by thermophilic composting has drawn increasing attention.This study investigated the effects of sawdust bio...Elimination of antibiotic resistance genes(ARGs)in animal manure from concentrated animal feeding operations by thermophilic composting has drawn increasing attention.This study investigated the effects of sawdust biochar,corn stover biochar and peanut hull biochar with three spiked levels on ARGs in swine manure during thermophilic composting.Thirteen ARGs corresponding to four classes of antibiotics(tetracyclines,sulfonamides,macrolides and quinolones)were determined in the composting piles.Results indicated that the ten tested composting groups became fully mature after 30-day thermophilic composting process.tetM,tetO and ermB were reduced in all tested groups;tetC and tetG,tetX,sul1,sul2,ermF,qnrD and aac(6’)-Ib were mostly reduced under low level biochar addition but increased under higher level biochar addition;gyrA increased under medium biochar addition and reduced in other groups;oqxB remained comparatively stable throughout the composting process.The addition levels of spiked biochar are more important than types of spiked biochar on the removal of ARGs in the composting pile.The average removal rates of ARGs in the control group,low,medium and high level biochar addition groups were 0.24 logs,0.52-0.72 logs,-0.52-0.18 logs and-0.19-0.21 logs,respectively.In summary,low level biochar addition could enhance the elimination of studied ARGs in swine manure during the composting process,while medium level biochar addition to the composting piles would increase the risk of ARGs’propagation.展开更多
In recent years,the utilization of manure resources for livestock and poultry farming has attracted a widespread attention,and manure resources utilization models suitable for different regional characteristics have f...In recent years,the utilization of manure resources for livestock and poultry farming has attracted a widespread attention,and manure resources utilization models suitable for different regional characteristics have formed gradually.Among them,the production of organic fertilizer from animal manure is a vital utilization method.However,there are still some problems such as high production costs,difficult sales,and the unwillingness of farmers to use organic fertilizers which have affected the breeding cycle and the sustainability of manure treatment in livestock and poultry breeding.This article selected 371 organic fertilizer plants,related farms and farmers in China,focusing on the main links of the entire process of livestock manure-organic fertilizer-farm application,and studied the mode of animal manure collection by organic fertilizer plants.The costs of organic fertilizer production and farmland application were discussed.Moreover,suggestions were made for the promotion and implementation of large-scale organic fertilizers to make good utilization of manure resources in livestock and poultry farming.展开更多
Fertilization mode affects soil quality and ecological health.The effects of four fertilization regimens on lignocellulose content,readily degradable carbohydrate decomposition,and potential microbial functions in the...Fertilization mode affects soil quality and ecological health.The effects of four fertilization regimens on lignocellulose content,readily degradable carbohydrate decomposition,and potential microbial functions in the topsoil of a wheat-maize rotation system between 2012 and 2017 were investigated.The fertilization regimens of control(control NFNB),high chemical fertilizer(HCF),high biochar plus low chemical fertilizer(HBLCF),and biochar-based fertilizer(BBF)were compared on soil fundamental properties,microbial structure,and potential function in soil carbohydrate degradation based on metagenome analysis.The diversity of carbohydrate-active enzyme genes in the topsoil microbial consortia in the four trials was primarily distributed within the ten ecologically most dominant phyla.Application of BBF was associated with the lowest decline in total nitrogen and P2O5(2012-2017:6.5%and 28.1%,respectively)and the most effective carbohydrate decomposition(2015-2017:67.0%for cellulose and 59.9%for readily degradable carbohydrate).Carbohydrate transport and metabolism accounted for 6.0%of reads assigned functional classification under the BBF regimen.These findings reveal the ecologically functional diversity of topsoil microorganisms and suggest BBF application as a promising strategy for sustainable agriculture and beneficial to soil health.展开更多
The great spatial and temporal variability in hydrological conditions and nitrogen（N）processing introduces large uncertainties to the identification of N sources and quantifying N cycles in plain river network regio...The great spatial and temporal variability in hydrological conditions and nitrogen（N）processing introduces large uncertainties to the identification of N sources and quantifying N cycles in plain river network regions. By combining isotopic data with chemical and hydrologic measurements, we determined the relative importance of N sources and biogeochemical N processes in the Taige River in the East Plain Region of China. The river was polluted more seriously by anthropogenic inputs in winter than in summer. Manure and urban sewage effluent were the main nitrate（NO-3） sources, with the nitrification of N-containing organic materials serving as another important source of NO-3. In the downstream, with minor variations in hydrological conditions, nitrification played a more important role than assimilation for the decreasing ammonium（NH＋4-N） concentrations.The N isotopic enrichment factors（ε） during NH＋4utilization ranged from- 13.88‰ in March to- 29.00‰ in July. The ratio of the increase in δ^18O and δ^15N of river NO-3in the downstream was 1.04 in January and 0.92 in March. This ratio indicated that NO-3assimilation by phytoplankton was responsible for the increasing δ^15N and δ^18O values of NO-3in winter. The relationships between δ^15N of particulate organic nitrogen and isotopic compositions of dissolved inorganic nitrogen indicated that the phytoplankton in the Taige River probably utilized NH＋4preferentially and mainly in summer, while in winter, NO-3assimilation by phytoplankton was dominant.展开更多
In order to identify the effect of geographic characteristics on the variations of nutrient concentrations and the utilization efficiency of nutrients by phytoplankton, data from 143 lakes, from 2008 to 2010, includin...In order to identify the effect of geographic characteristics on the variations of nutrient concentrations and the utilization efficiency of nutrients by phytoplankton, data from 143 lakes, from 2008 to 2010, including three very different types of topography, i.e., the first topography ladder（FTL）, second topography ladder（STL）, and third topography ladder（TTL）, were statistically analyzed. Lakes in the FTL and STL, located at high elevation（above1000 m） and low longitudes（lower than 105° E）, were sporadically oligotrophic, whereas lakes in the TTL were almost all mesotrophic and eutrophic. The trophic level index（TLI）became higher with the rise of longitude. Two turning points（5 and 15°C） on the curve of TLI as function of the average annual temperature（AAT） corresponded with the AAT in different lake regions in the STL and TTL. Because the responses of TLI to AAT differ significantly, there were variations of nutrient and algal biomass concentrations in different lake regions in the same type of topography ladder. According to the differences in utilization efficiency of total nitrogen or total phosphorus by phytoplankton, China could be partitioned into six lake regions. Scientific nutrient criteria for each lake region shall be established considering these differences in China.展开更多
Effective microorganisms(EM)is usually used in composting to improve the composting process.However,the effect of EM on heavy metals evolution was still unclear.This study was performed to illustrate the microbial com...Effective microorganisms(EM)is usually used in composting to improve the composting process.However,the effect of EM on heavy metals evolution was still unclear.This study was performed to illustrate the microbial community changes that occur during composting with the addition of EM and to determine the evolution of heavy metal speciation during this process.The requirement of harmlessness for pig manure was met after the addition of EM at a dosage of 0.5%,with a germination index of 96.42%.The bacterial and fungal diversity were both found to decrease during the composting process.Additionally,the bioavailability of Cu and Pb decreased significantly during composting.Significant correlations were observed between the microbial composition and the percentage of different heavy metals fractions;however,the mechanism responsible for this correlation requires further investigation.This study has the potential to contribute to control of heavy metal contamination during the process of recycling pig manure through the controlled addition of EM.展开更多
The objective of this study was to investigate the relationship between ammonium(NH^(+)_(4)-N)dynamic sorption capacity and physicochemical properties of modified biochars.Biochars,producing from three species of agri...The objective of this study was to investigate the relationship between ammonium(NH^(+)_(4)-N)dynamic sorption capacity and physicochemical properties of modified biochars.Biochars,producing from three species of agricultural wastes of cornstalk(A),corncob(B)and sawdust(C)at 550°C,600°C and 650°C,were modified by four methods of NaOH plus microwave(NaM),KOH(K),FeCl 3(Fe)and HNO 3(H).The static and dynamic adsorption experiments were conducted to investigate sorption characteristics of modified biochars on NH^(+)_(4)-N in slurry of piggery manure anaerobic digestate.Four modified biochars with better NH^(+)_(4)-N adsorption rates were selected through static kinetics adsorption tests,which showed that chemical reactions might have occurred during the NH^(+)_(4)-N sorption process and the maximum NH^(+)_(4)-N removal rates of B-550-Fe,A-550-NaM,A-550-K and C-600-NaM were 66.64%,57.50%,52.39%and 45.20%,respectively.The dynamic adsorption column experiment was conducted in a three-stage adsorption column packed with the selected three modified biochars.NH^(+)_(4)-N dynamic adsorption depended on the slurry inflow flow rate,the type of biochar and the depth of packed biochar.The optimal adsorption process was elected by the method of orthogonal experiment.The data showed that using deeper packed biochar and applying lower flow rates could be a better strategy to increase NH^(+)_(4)-N adsorption.The maximum NH^(+)_(4)-N removal rate in the slurry could reach 85.60%in the three-stage adsorption process.It concluded that NH^(+)_(4)-N adsorption in three-stage adsorption process could be an effective method to recover nitrogen from piggery manure anaerobic digestate.展开更多
A nationwide survey of organic fertilizer was carried out in China,and 263 samples were collected to be analyzed for maturity indices(moisture content(MC),pH,electrical conductivity(EC),E4/E6,and germination index(GI)...A nationwide survey of organic fertilizer was carried out in China,and 263 samples were collected to be analyzed for maturity indices(moisture content(MC),pH,electrical conductivity(EC),E4/E6,and germination index(GI))and 7 heavy metals(Cu,Zn,Cd,Pb,Cr,As and Ni).The MC,pH,EC,E4/E6 and GI showed large variations among the organic fertilizer samples with ranges of 6.9%-66.68%,4.40-9.19,0.76-13.38 mS/cm,1.07-9.40,and 10%-150%,respectively.The concentrations of 7 heavy metals(Cu,Zn,Cd,Pb,As,Cr,Ni)were also with large variations at 7.53-580.4,0-2818,0.02-149.3,0(not detected)-1321,0.14-26.9,3.70-1237,and 0(not detected)-214.6 mg/kg dry weight.Compared with the limit values of the Chinese standard for organic fertilizers(NY525-2012),9.51%,73.4%,3.19%,and 3.04%of the samples exceeded the limit values of Cd,Pb,As and Cr,respectively.No limits have been set for Cu,Zn and Ni in China,and 35.0%,13.3%and 16.7%of the samples exceeded the Cu,Zn and Ni limits for composts in Germany,respectively.Monte Carlo simulations indicated that with the continuous application of organic fertilizer,Cu,Zn,Cd,Pb and Cr would accumulate to the risk control standard for soil contamination of agricultural land(GB15618-2018)within a relatively short period.It is urgent to establish suitable limits of heavy metals in organic fertilizer in China to control the risk of heavy metal pollution in agricultural land.展开更多
基金The project acknowledges that this work was financially supported by the Open Project of Key Laboratory of Ministry of Agriculture and Rural Affairs(KLTMCUAR2020-3).
文摘Composting is a suitable low-cost strategy to transform animal waste into a stabilized end product,and the airflow field in the pile affects the fermentation states.For piles in the aeration weak zone,anaerobic fermentation may happen as the lack of oxygen.While in practice,due to the extremely low speed and harsh condition,the airflow field was scarcely researched.This study adopted Computational Fluid Dynamics(CFD)to investigate the airflow field in the compost pile.A three-dimensional CFD model was built;the compost pile in this model was simplified as porous media;unstructured mesh was adopted to discretize the geometric model;standard k-εmodel and SIMPLE scheme were employed for numerical methods.The CFD model was validated with the field experiment in the cooling period.Then the model was applied to research the airflow field in the pile with increased pipe diameter.Results showed that it was feasible to investigate the airflow field in the pile with CFD.For boundary conditions in the CFD model,treating the compost pile as a homogeneous porous media is reasonable.The CFD model was successfully validated by the field measurement(the average relative difference between the simulated and measured air speed was within 10%).Airflow in the existing compost pile showed nonuniform distribution with stagnation and vortex zones;the turbulence intensities were 3.57 and 1.43 for the airflow in the pile and the reactor,respectively.When pipe diameter increased,the airflow distribution uniformity in the pile was improved significantly.With diameter raising to 0.04 m,the turbulence intensity decreased to 1.54 and 0.42 for the airflow in the pile and the reactor,respectively.The CFD model developed in this research can provide qualitative and quantitative analyses of the airflow field in compost piles,and can be a theoretical basis for the aeration system design.
基金The project was financially supported by the National Key R&D Program of China(2017YFD0800800).
文摘Elimination of antibiotic resistance genes(ARGs)in animal manure from concentrated animal feeding operations by thermophilic composting has drawn increasing attention.This study investigated the effects of sawdust biochar,corn stover biochar and peanut hull biochar with three spiked levels on ARGs in swine manure during thermophilic composting.Thirteen ARGs corresponding to four classes of antibiotics(tetracyclines,sulfonamides,macrolides and quinolones)were determined in the composting piles.Results indicated that the ten tested composting groups became fully mature after 30-day thermophilic composting process.tetM,tetO and ermB were reduced in all tested groups;tetC and tetG,tetX,sul1,sul2,ermF,qnrD and aac(6’)-Ib were mostly reduced under low level biochar addition but increased under higher level biochar addition;gyrA increased under medium biochar addition and reduced in other groups;oqxB remained comparatively stable throughout the composting process.The addition levels of spiked biochar are more important than types of spiked biochar on the removal of ARGs in the composting pile.The average removal rates of ARGs in the control group,low,medium and high level biochar addition groups were 0.24 logs,0.52-0.72 logs,-0.52-0.18 logs and-0.19-0.21 logs,respectively.In summary,low level biochar addition could enhance the elimination of studied ARGs in swine manure during the composting process,while medium level biochar addition to the composting piles would increase the risk of ARGs’propagation.
基金This work was supported by the National Key R&D Program of China(2017YFD0800800).
文摘In recent years,the utilization of manure resources for livestock and poultry farming has attracted a widespread attention,and manure resources utilization models suitable for different regional characteristics have formed gradually.Among them,the production of organic fertilizer from animal manure is a vital utilization method.However,there are still some problems such as high production costs,difficult sales,and the unwillingness of farmers to use organic fertilizers which have affected the breeding cycle and the sustainability of manure treatment in livestock and poultry breeding.This article selected 371 organic fertilizer plants,related farms and farmers in China,focusing on the main links of the entire process of livestock manure-organic fertilizer-farm application,and studied the mode of animal manure collection by organic fertilizer plants.The costs of organic fertilizer production and farmland application were discussed.Moreover,suggestions were made for the promotion and implementation of large-scale organic fertilizers to make good utilization of manure resources in livestock and poultry farming.
基金This work was supported by the Profession Scientific Research Special Item of Agricultural Public Welfare of China(Grant No.201503135-2).
文摘Fertilization mode affects soil quality and ecological health.The effects of four fertilization regimens on lignocellulose content,readily degradable carbohydrate decomposition,and potential microbial functions in the topsoil of a wheat-maize rotation system between 2012 and 2017 were investigated.The fertilization regimens of control(control NFNB),high chemical fertilizer(HCF),high biochar plus low chemical fertilizer(HBLCF),and biochar-based fertilizer(BBF)were compared on soil fundamental properties,microbial structure,and potential function in soil carbohydrate degradation based on metagenome analysis.The diversity of carbohydrate-active enzyme genes in the topsoil microbial consortia in the four trials was primarily distributed within the ten ecologically most dominant phyla.Application of BBF was associated with the lowest decline in total nitrogen and P2O5(2012-2017:6.5%and 28.1%,respectively)and the most effective carbohydrate decomposition(2015-2017:67.0%for cellulose and 59.9%for readily degradable carbohydrate).Carbohydrate transport and metabolism accounted for 6.0%of reads assigned functional classification under the BBF regimen.These findings reveal the ecologically functional diversity of topsoil microorganisms and suggest BBF application as a promising strategy for sustainable agriculture and beneficial to soil health.
基金supported by the Mega-projects of Science Research for Water Environment Improvement (No. 2012ZX07101)
文摘The great spatial and temporal variability in hydrological conditions and nitrogen（N）processing introduces large uncertainties to the identification of N sources and quantifying N cycles in plain river network regions. By combining isotopic data with chemical and hydrologic measurements, we determined the relative importance of N sources and biogeochemical N processes in the Taige River in the East Plain Region of China. The river was polluted more seriously by anthropogenic inputs in winter than in summer. Manure and urban sewage effluent were the main nitrate（NO-3） sources, with the nitrification of N-containing organic materials serving as another important source of NO-3. In the downstream, with minor variations in hydrological conditions, nitrification played a more important role than assimilation for the decreasing ammonium（NH＋4-N） concentrations.The N isotopic enrichment factors（ε） during NH＋4utilization ranged from- 13.88‰ in March to- 29.00‰ in July. The ratio of the increase in δ^18O and δ^15N of river NO-3in the downstream was 1.04 in January and 0.92 in March. This ratio indicated that NO-3assimilation by phytoplankton was responsible for the increasing δ^15N and δ^18O values of NO-3in winter. The relationships between δ^15N of particulate organic nitrogen and isotopic compositions of dissolved inorganic nitrogen indicated that the phytoplankton in the Taige River probably utilized NH＋4preferentially and mainly in summer, while in winter, NO-3assimilation by phytoplankton was dominant.
基金supported by the Mega-projects of Science Research for Water Environment Improvement (Nos. 2012ZX07 101, 2009ZX07106-001)
文摘In order to identify the effect of geographic characteristics on the variations of nutrient concentrations and the utilization efficiency of nutrients by phytoplankton, data from 143 lakes, from 2008 to 2010, including three very different types of topography, i.e., the first topography ladder（FTL）, second topography ladder（STL）, and third topography ladder（TTL）, were statistically analyzed. Lakes in the FTL and STL, located at high elevation（above1000 m） and low longitudes（lower than 105° E）, were sporadically oligotrophic, whereas lakes in the TTL were almost all mesotrophic and eutrophic. The trophic level index（TLI）became higher with the rise of longitude. Two turning points（5 and 15°C） on the curve of TLI as function of the average annual temperature（AAT） corresponded with the AAT in different lake regions in the STL and TTL. Because the responses of TLI to AAT differ significantly, there were variations of nutrient and algal biomass concentrations in different lake regions in the same type of topography ladder. According to the differences in utilization efficiency of total nitrogen or total phosphorus by phytoplankton, China could be partitioned into six lake regions. Scientific nutrient criteria for each lake region shall be established considering these differences in China.
基金The project was financially supported by the National Key R&D Program of China(2018YFD0500205).
文摘Effective microorganisms(EM)is usually used in composting to improve the composting process.However,the effect of EM on heavy metals evolution was still unclear.This study was performed to illustrate the microbial community changes that occur during composting with the addition of EM and to determine the evolution of heavy metal speciation during this process.The requirement of harmlessness for pig manure was met after the addition of EM at a dosage of 0.5%,with a germination index of 96.42%.The bacterial and fungal diversity were both found to decrease during the composting process.Additionally,the bioavailability of Cu and Pb decreased significantly during composting.Significant correlations were observed between the microbial composition and the percentage of different heavy metals fractions;however,the mechanism responsible for this correlation requires further investigation.This study has the potential to contribute to control of heavy metal contamination during the process of recycling pig manure through the controlled addition of EM.
基金The present study was supported by the project of Indigenous Research and Development Program of AAPE(2018ZZYF0101)and Public Welfare Industry(Agriculture)Special Scientific Research(201503135).
文摘The objective of this study was to investigate the relationship between ammonium(NH^(+)_(4)-N)dynamic sorption capacity and physicochemical properties of modified biochars.Biochars,producing from three species of agricultural wastes of cornstalk(A),corncob(B)and sawdust(C)at 550°C,600°C and 650°C,were modified by four methods of NaOH plus microwave(NaM),KOH(K),FeCl 3(Fe)and HNO 3(H).The static and dynamic adsorption experiments were conducted to investigate sorption characteristics of modified biochars on NH^(+)_(4)-N in slurry of piggery manure anaerobic digestate.Four modified biochars with better NH^(+)_(4)-N adsorption rates were selected through static kinetics adsorption tests,which showed that chemical reactions might have occurred during the NH^(+)_(4)-N sorption process and the maximum NH^(+)_(4)-N removal rates of B-550-Fe,A-550-NaM,A-550-K and C-600-NaM were 66.64%,57.50%,52.39%and 45.20%,respectively.The dynamic adsorption column experiment was conducted in a three-stage adsorption column packed with the selected three modified biochars.NH^(+)_(4)-N dynamic adsorption depended on the slurry inflow flow rate,the type of biochar and the depth of packed biochar.The optimal adsorption process was elected by the method of orthogonal experiment.The data showed that using deeper packed biochar and applying lower flow rates could be a better strategy to increase NH^(+)_(4)-N adsorption.The maximum NH^(+)_(4)-N removal rate in the slurry could reach 85.60%in the three-stage adsorption process.It concluded that NH^(+)_(4)-N adsorption in three-stage adsorption process could be an effective method to recover nitrogen from piggery manure anaerobic digestate.
基金The present study was supported by the project the National Key Research and Development Program of China(2016YFD0800603).
文摘A nationwide survey of organic fertilizer was carried out in China,and 263 samples were collected to be analyzed for maturity indices(moisture content(MC),pH,electrical conductivity(EC),E4/E6,and germination index(GI))and 7 heavy metals(Cu,Zn,Cd,Pb,Cr,As and Ni).The MC,pH,EC,E4/E6 and GI showed large variations among the organic fertilizer samples with ranges of 6.9%-66.68%,4.40-9.19,0.76-13.38 mS/cm,1.07-9.40,and 10%-150%,respectively.The concentrations of 7 heavy metals(Cu,Zn,Cd,Pb,As,Cr,Ni)were also with large variations at 7.53-580.4,0-2818,0.02-149.3,0(not detected)-1321,0.14-26.9,3.70-1237,and 0(not detected)-214.6 mg/kg dry weight.Compared with the limit values of the Chinese standard for organic fertilizers(NY525-2012),9.51%,73.4%,3.19%,and 3.04%of the samples exceeded the limit values of Cd,Pb,As and Cr,respectively.No limits have been set for Cu,Zn and Ni in China,and 35.0%,13.3%and 16.7%of the samples exceeded the Cu,Zn and Ni limits for composts in Germany,respectively.Monte Carlo simulations indicated that with the continuous application of organic fertilizer,Cu,Zn,Cd,Pb and Cr would accumulate to the risk control standard for soil contamination of agricultural land(GB15618-2018)within a relatively short period.It is urgent to establish suitable limits of heavy metals in organic fertilizer in China to control the risk of heavy metal pollution in agricultural land.
