The production of toxic sulfides is a common environmental problem in mariculture.Therefore,the effective inhibition of sulfidogens is the key to prevent sulfides production.In this study,the possibility and mechanism...The production of toxic sulfides is a common environmental problem in mariculture.Therefore,the effective inhibition of sulfidogens is the key to prevent sulfides production.In this study,the possibility and mechanism of nitrate(NO_(3)^(−))inhibiting the activity of the sulfate-reducing microbiota(SRM)from mariculture sediments was investigated.The results showed that 1,3,and 5 mmol L^(−1)NO_(3)^(−)continuously inhibited sulfide production for 1-3 d.As NO_(3)^(−) dosage increased to 7 mmol L^(−1),the duration of inhibition increased to 6 days.Denitrifying product NO_(2)^(−)heavily inhibited the activity of dissimilar sulfate reductase gene(dsrB)by 3 orders,which was the main reason that the sulfate-reducing activity was inhibited.The SRM structure changed significantly with the dosage of NO_(3)^(−),while the abundance of sulfidogens Desulfovibrio species increased due to their capability of detoxifying nitrite through nitrite reductase.Hence,sulfidogens Desulfovibrio species are more adaptable to a high nitrate/nitrite environment,and the traditional control strategies by dosing nitrate/nitrite should be paid more attention to.The findings will serve as helpful guidelines for sulfate-reducing microbiota in the habitat of mariculture to reduce their generation of poisonous sulfide.展开更多
The impact of dissolved oxygen(DO)at aerobic phase on the nitrogen removal,extracellular polymeric substances(EPS),microbial activity and microbial community of sequencing batch biofilm reactor(SBBR)have been evaluate...The impact of dissolved oxygen(DO)at aerobic phase on the nitrogen removal,extracellular polymeric substances(EPS),microbial activity and microbial community of sequencing batch biofilm reactor(SBBR)have been evaluated in treating mariculture wastewater.The oxygen uptake rate and nitrification rate declined with DO concentration from 3–4 to 1–1.5mgL^(-1),whereas the denitrification rate had an increment.The activities of nitrifying enzymes reduced with the decrease of DO concentration at aerobic phase,but those of denitrifying enzymes illustrated opposite results.The nitrification and denitrification rates displayed the similar variation tendency with the relevant enzymatic activities as DO concentration decreased.The protein(PN)and polysaccharide(PS)content in EPS decreased as DO concentration declined,whereas the PN/PS ratio increased.The microbial community showed obvious difference as DO concentration decreased from 3–4 to 1–1.5mgL^(-1).The microbial co-occurrence,keystone taxa and sig-nificant difference illustrated some variations at different DO concentrations.展开更多
This study aimed to present a novel clay/biochar composite adsorption particle, which made from abandoned reed straw and clay to remove ammonia nitrogen(NH4^+-N) from micro-contaminated water. The removal performance ...This study aimed to present a novel clay/biochar composite adsorption particle, which made from abandoned reed straw and clay to remove ammonia nitrogen(NH4^+-N) from micro-contaminated water. The removal performance of NH4^+-N by composite adsorption particle was monitored under different raw material proportions and initial NH4^+-N concentration. Besides, adsorption kinetics and adsorption isotherms were investigated to reveal the adsorption mechanisms. The results showed that NH4^+-N was effectively removed under optimal proportion of biochar, foaming agent and crosslinker with 20%, 3%, and 3%, respectively. The optimal contact time was 150 min and the best removal efficiency was 88.6% at initial NH4^+-N concentration of 20 mg L^-1. The adsorption performance was well described by the second order kinetic model and Freundlich model. The novel clay/biochar composite adsorption particle in this study demonstrated a high potential for NH4^+-N removal from surface water.展开更多
The dynamic microcosms were used to evaluate the effect of oil spills on microbial ecological system in marine sediment and the enhancement of nutrient on the oil removal. The function and structure of microbial commu...The dynamic microcosms were used to evaluate the effect of oil spills on microbial ecological system in marine sediment and the enhancement of nutrient on the oil removal. The function and structure of microbial community caused by the oil pollution and phosphate dosage were simultaneously monitored by dehydrogenase activity assay and PCR-denaturing gradient gel electrophoresis(DGGE) techniques. The results indicated that the amount of total bacteria in all dynamic microcosms declined rapidly with incubation time. The number of petroleum-degrading bacteria and the activity of sediment dehydrogenase were gradually enhanced by petroleum in the oil-treated microcosms, while they both showed no obvious response to phosphate dosage. In comparison, phosphate spiked heterotrophic bacteria and they showed a significant increase in amount. DGGE profiles indicated that petroleum dosage greatly changed community structure, and the bacteria belonged to class Deltaproteobacteria, and phyla Bacteroidetes and Chlorobi were enriched. This study demonstrated that petroleum input greatly impacted the microbial community structure and consequently the marine sediment petroleum-degrading activity was enhanced. Phosphate dosage would multiply heterotrophic bacteria but not significantly enhance the petroleum degradation.展开更多
In order to explore the effect of carbon and nitrogen(C/N)ratio on the performance of anoxic/aerobic-moving bed bio-film reactor(A/O-MBBR)process for treating mariculture wastewater,a laboratory-scale A/O-MBBR was con...In order to explore the effect of carbon and nitrogen(C/N)ratio on the performance of anoxic/aerobic-moving bed bio-film reactor(A/O-MBBR)process for treating mariculture wastewater,a laboratory-scale A/O-MBBR was conducted.The results showed that the reduction of C/N ratio was conducive to improving the removal efficiency of chemical oxygen demand(COD)and ammonia nitrogen(NH_(4)^(+)-N),while inhibiting that of nitrite nitrogen(NO_(2)^(−)-N)and nitrate nitrogen(NO_(3)^(−)-N).The extracellular polymeric substances(EPS)in anoxic zone were significantly higher in concentration than that in aerobic zone although they both declined with decrease of C/N ratio.The result provides solid support for better controlling the pollution of mariculture wastewater.展开更多
The wide application of antibiotics in aquaculture requires an efficient treatment of the wastewater before discharging it into the environment.During the wastewater treatment,the influence of antibiotics on the perfo...The wide application of antibiotics in aquaculture requires an efficient treatment of the wastewater before discharging it into the environment.During the wastewater treatment,the influence of antibiotics on the performance of bioreactor should be well revealed due to their toxicity to the functional microbial community.In this study,the effect of feeding 10-30 mg L−1 sulfamethoxazole(SMX)in influent on the performance of an anoxic/oxic-moving bed biofilm reactor(A/O-MBBR)treating mariculture wastewater and the responding change of biofilm microbial communities was investigated.The COD average removal rate remained at 94.61%-97.34%with the dosage of SMX.Compared with that,the nitrifying removals of NH4+-N and NO2−-N were violently inhibited by 30 mg L−1 SMX and denitrifying removal of the NO3−-N decreased obviously with 20 mg L−1 or more SMX.The microbial community in the successful startup bioreactor was relatively abundant,while the diversity of microbial community decreased with the increase of feeding SMX.The salt-tolerant and SMX-resistant genera Arcobacter,Thiothrix,Desulfuromusa and Nitrosomonas were gradually enriched and finally played a vital role in converting COD and recycling nitrogen and sulfur.Hence,the present A/O-MBBR reactor with the salt-tolerant functional microbiota achieved efficient removal of pollutants in the presence of low concentration(e.g.,10 mg L−1)SMX.展开更多
The dust storms from the continent usually affect the abundance and diversity of planktons by supplying trace elements. As such, the response of heterotrophic planktonic bacteria to dusts, nutrients(i.e., nitrogen and...The dust storms from the continent usually affect the abundance and diversity of planktons by supplying trace elements. As such, the response of heterotrophic planktonic bacteria to dusts, nutrients(i.e., nitrogen and phosphorus) or ferrous dosages was investigated in the Kuroshio Extension region of the Northwest Pacific Ocean(NWPO) through on-board incubation experiments during an oceanographic survey in spring 2014. The flow cytometry and 16S rRNA high-throughput sequencing methods were applied to explore the abundance and community structure of bacteria, and the percentage of high nucleic acid bacteria(HNA%). The results showed that the heterotrophic bacteria abundance was low(average 2.55×10^5 cells mL^-1) and subjected to both nitrogen(N) and ferrous(Fe) limitation. Sand-dust deposition observably promoted the activity of heterotrophic planktonic bacteria. The maximum abundance of heterotrophic bacteria was 6.98×10^5 cells mL^-1 in the dust-dosage group, which was 44% higher than the control(P < 0.05). The HNA% in the dust-dosage group was 1.37 times higher than the control(P < 0.05). The activation mechanism was mainly related to the dissolution of N and Fe in the dusts. The relative abundance of genus Winogradskyella was significantly increased by dust deposition while the relative abundance of the genera Tenacibaculum and Hyphomonas was decreased. These variations of bacterial community structure were ascribed to the dissolution of nutrients N and P. Comparing the results of different experimental groups, this study concluded that dust storm improved the abundance of heterotrophic bacteria by dissolution of N and Fe.展开更多
To biologically inhibit the production of highly toxic sulfide in the aquaculture area,one bacterium,designated as Hydrogenovibrio thermophilus strain TT,was isolated from sediment in Jiaozhou Bay,China.The strain was...To biologically inhibit the production of highly toxic sulfide in the aquaculture area,one bacterium,designated as Hydrogenovibrio thermophilus strain TT,was isolated from sediment in Jiaozhou Bay,China.The strain was found to be microaerobic mixtrophic,employing both carbon dioxide and organic carbons,e.g.citrate,lactate,glucose,and peptone as carbon sources.When it oxidized the sulfide and thiosulfate,oxygen was the optimal electron acceptor,followed by nitrite and nitrate,which benefited to removal of sulfide under low-oxygen mariculture environment.In addition,the strain TT exhibited remarkable tolerance of sulfide and thiosulfate in seawater,and it was able to oxidize 18.52 mmol L^-1 S^2-in 12 h or 45 mmol L^-1 S2O3^2-in 24 h at initial pH 7.0-9.0,30-40℃.Therefore,this strain showed a quite promising application for biological remediation of sulfide-contaminated mariculture system.展开更多
High salt and low temperature are the bottlenecks for the remove of oil contaminants by enriched crude-oil degrading microbiota in Liaohe Estuarine Wetland(LEW),China.To improve the performance of crude-oil removal,mi...High salt and low temperature are the bottlenecks for the remove of oil contaminants by enriched crude-oil degrading microbiota in Liaohe Estuarine Wetland(LEW),China.To improve the performance of crude-oil removal,microbiota was further immobilized by two methods,i.e.,sodium alginate(SA),and polyvinyl alcohol and sodium alginate(PVA+SA).Results showed that the crude oil was effectively removed by the enrichment with an average degrading ratio of 19.42-31.45 mg(L d)^(−1).The optimal inoculum size for the n-alkanes removal was 10%and 99.89%.Some members of genera Acinetobacter,Actinophytocola,Aquabac-terium,Dysgonomonas,Frigidibacter,Sphingobium,Serpens,and Pseudomonas dominated in crude-oil degrading microflora.Though the removal efficiency was lower than free bacteria when the temperature was 15℃,SA and PVA+SA immobilization im-proved the resistance to salinity.The composite crude-oil degrading microbiota in this study demonstrated a perspective potential for crude oil removal from surface water under high salinity and low temperature conditions.展开更多
Sorption mechanisms of sulfamethazine(SMT)in different pH solutions are complicated.It has not been sufficiently investigated to enhance removal of SMT from alkalescent aqueous solution.In this study,sorption isotherm...Sorption mechanisms of sulfamethazine(SMT)in different pH solutions are complicated.It has not been sufficiently investigated to enhance removal of SMT from alkalescent aqueous solution.In this study,sorption isotherms and kinetics of SMT by corn biochars pyrolyzed at 300℃ and 600℃(300C,600C)under diverse pH conditions were compared.In order to improve the sorption efficiency of SMT from alkalescent aqueous solution,the biochar 300C was modified by acid or base.Different mathematic models were used to describe sorption driving force and sorption process.Results showed that the biochar 300C possessed more amorphous organic carbon and polar functional groups,which led to a higher sorption capacity than biochar 600C.The sorption rate of biochar 300C was greater than 600C under diverse pH as the physisorption of 300C outweighed 600C.The SMT presented stronger hydrophobicity at pH 5 and higher electrostatic repulsion at pH 1 or 8,which resulted in a higher combining capacity of SMT with both biochars at pH 5 than other pH values.In addition,the acid modified biochar had better removal effect on SMT than alkali at pH solution around 8.The research provides a theoretical basis for the removal of SMT from alkalescent aqueous solution.展开更多
The effects of phenanthrene(Phe)on the denitrification activity and denitrifying genes(narG,nirS and nosZ)were evaluated by dose-response experiments in sediments of Dagu River Estuary(DRE)and Jiaozhou Bay(JZB).The re...The effects of phenanthrene(Phe)on the denitrification activity and denitrifying genes(narG,nirS and nosZ)were evaluated by dose-response experiments in sediments of Dagu River Estuary(DRE)and Jiaozhou Bay(JZB).The results showed that potential denitrification activity(PDA),N2O,NO3−and NO2−reduction rates of both areas were inhibited with an increase of Phe concentrations.The PDA,N2O,NO3−and NO2−reduction rates of both areas was highest and lowest in the control(DRE:0.453,0.427,7.439 and 3.222mgNkg−1 h−1,JZB:0.592,0.555,8.470 and 3.793mgNkg−1 h−1)and highest Phe amended treatments(DRE:0.069,0.001,4.486,and 1.563 mgNkg−1 h−1;JZB:0.114,0.024,5.527 and 2.200 mgNkg−1 h−1).The inhibition rate of PDA was highest,follow by NO2−reduction and then NO3−reduction.Moreover,with the increasing of Phe concentrations,total bacteria count and the abundance of denitrifying genes were decreased.And N2O accumulation was promoted with the addition of Phe for both areas.Based on the comparison of EC50 values,denitrifiers harboring three genes were more sensitive to Phe than PDA,and denitrifiers harboring nirS gene were more sensitive,followed by nosZ gene,and then narG gene.Furthermore,according to correlation analysis,the relative abundance of denitrifying genes was much more positively correlated with PDA,NO3−and NO2−reduction than total bacteria count.In addition,the denitrification activity and total bacteria count in JZB were more inhibited than that of DRE.This study is useful for understanding the impact of Phe pollution on denitrification in estuary and marine sediments,with profound implications for the management of aquatic ecosystems regarding eutrophication(N-removal)and greenhouse effect.展开更多
基金supported by the National Natural Science Foundation of China(No.41977315)the Fundamental Research Funds for the Central Universities of China(No.201964004).
文摘The production of toxic sulfides is a common environmental problem in mariculture.Therefore,the effective inhibition of sulfidogens is the key to prevent sulfides production.In this study,the possibility and mechanism of nitrate(NO_(3)^(−))inhibiting the activity of the sulfate-reducing microbiota(SRM)from mariculture sediments was investigated.The results showed that 1,3,and 5 mmol L^(−1)NO_(3)^(−)continuously inhibited sulfide production for 1-3 d.As NO_(3)^(−) dosage increased to 7 mmol L^(−1),the duration of inhibition increased to 6 days.Denitrifying product NO_(2)^(−)heavily inhibited the activity of dissimilar sulfate reductase gene(dsrB)by 3 orders,which was the main reason that the sulfate-reducing activity was inhibited.The SRM structure changed significantly with the dosage of NO_(3)^(−),while the abundance of sulfidogens Desulfovibrio species increased due to their capability of detoxifying nitrite through nitrite reductase.Hence,sulfidogens Desulfovibrio species are more adaptable to a high nitrate/nitrite environment,and the traditional control strategies by dosing nitrate/nitrite should be paid more attention to.The findings will serve as helpful guidelines for sulfate-reducing microbiota in the habitat of mariculture to reduce their generation of poisonous sulfide.
基金supported by the National Natural Science Foundation of China(No.52070172)the Fundamental Research Funds for the Central Universities(No.201964003).
文摘The impact of dissolved oxygen(DO)at aerobic phase on the nitrogen removal,extracellular polymeric substances(EPS),microbial activity and microbial community of sequencing batch biofilm reactor(SBBR)have been evaluated in treating mariculture wastewater.The oxygen uptake rate and nitrification rate declined with DO concentration from 3–4 to 1–1.5mgL^(-1),whereas the denitrification rate had an increment.The activities of nitrifying enzymes reduced with the decrease of DO concentration at aerobic phase,but those of denitrifying enzymes illustrated opposite results.The nitrification and denitrification rates displayed the similar variation tendency with the relevant enzymatic activities as DO concentration decreased.The protein(PN)and polysaccharide(PS)content in EPS decreased as DO concentration declined,whereas the PN/PS ratio increased.The microbial community showed obvious difference as DO concentration decreased from 3–4 to 1–1.5mgL^(-1).The microbial co-occurrence,keystone taxa and sig-nificant difference illustrated some variations at different DO concentrations.
基金supported by the National Major Project of Water Pollution Control and Management Technology in China (No.2013ZX07202-007)the Shenzhen Science and Technology Project (No.GRCK2017042116092660)the National Natural Science Foundation of China (No.51308066)。
文摘This study aimed to present a novel clay/biochar composite adsorption particle, which made from abandoned reed straw and clay to remove ammonia nitrogen(NH4^+-N) from micro-contaminated water. The removal performance of NH4^+-N by composite adsorption particle was monitored under different raw material proportions and initial NH4^+-N concentration. Besides, adsorption kinetics and adsorption isotherms were investigated to reveal the adsorption mechanisms. The results showed that NH4^+-N was effectively removed under optimal proportion of biochar, foaming agent and crosslinker with 20%, 3%, and 3%, respectively. The optimal contact time was 150 min and the best removal efficiency was 88.6% at initial NH4^+-N concentration of 20 mg L^-1. The adsorption performance was well described by the second order kinetic model and Freundlich model. The novel clay/biochar composite adsorption particle in this study demonstrated a high potential for NH4^+-N removal from surface water.
基金supported by the National Natural Science Foundation of China (Grant No.40801193)the Basic Research Projects of Qingdao Science and Technology Program (12-1-4-1-(12)-jch)the Scientific Research Foundation for the Excellent Middle-Aged and Youth Scientists of Shandong Province of China (BS2011NJ018)
文摘The dynamic microcosms were used to evaluate the effect of oil spills on microbial ecological system in marine sediment and the enhancement of nutrient on the oil removal. The function and structure of microbial community caused by the oil pollution and phosphate dosage were simultaneously monitored by dehydrogenase activity assay and PCR-denaturing gradient gel electrophoresis(DGGE) techniques. The results indicated that the amount of total bacteria in all dynamic microcosms declined rapidly with incubation time. The number of petroleum-degrading bacteria and the activity of sediment dehydrogenase were gradually enhanced by petroleum in the oil-treated microcosms, while they both showed no obvious response to phosphate dosage. In comparison, phosphate spiked heterotrophic bacteria and they showed a significant increase in amount. DGGE profiles indicated that petroleum dosage greatly changed community structure, and the bacteria belonged to class Deltaproteobacteria, and phyla Bacteroidetes and Chlorobi were enriched. This study demonstrated that petroleum input greatly impacted the microbial community structure and consequently the marine sediment petroleum-degrading activity was enhanced. Phosphate dosage would multiply heterotrophic bacteria but not significantly enhance the petroleum degradation.
基金This work was supported by the National Key Research and Development Program of China(No.2018 YFC1407601)the Start-up Foundation for Introducing Talent of NUIST and Guangxi Innovation Driven Development Project(major science and technology project).
文摘In order to explore the effect of carbon and nitrogen(C/N)ratio on the performance of anoxic/aerobic-moving bed bio-film reactor(A/O-MBBR)process for treating mariculture wastewater,a laboratory-scale A/O-MBBR was conducted.The results showed that the reduction of C/N ratio was conducive to improving the removal efficiency of chemical oxygen demand(COD)and ammonia nitrogen(NH_(4)^(+)-N),while inhibiting that of nitrite nitrogen(NO_(2)^(−)-N)and nitrate nitrogen(NO_(3)^(−)-N).The extracellular polymeric substances(EPS)in anoxic zone were significantly higher in concentration than that in aerobic zone although they both declined with decrease of C/N ratio.The result provides solid support for better controlling the pollution of mariculture wastewater.
基金the Fundamental Research Funds for the Central Universities of China(No.201964004)the National Natural Science Foundation of China(No.41977315).
文摘The wide application of antibiotics in aquaculture requires an efficient treatment of the wastewater before discharging it into the environment.During the wastewater treatment,the influence of antibiotics on the performance of bioreactor should be well revealed due to their toxicity to the functional microbial community.In this study,the effect of feeding 10-30 mg L−1 sulfamethoxazole(SMX)in influent on the performance of an anoxic/oxic-moving bed biofilm reactor(A/O-MBBR)treating mariculture wastewater and the responding change of biofilm microbial communities was investigated.The COD average removal rate remained at 94.61%-97.34%with the dosage of SMX.Compared with that,the nitrifying removals of NH4+-N and NO2−-N were violently inhibited by 30 mg L−1 SMX and denitrifying removal of the NO3−-N decreased obviously with 20 mg L−1 or more SMX.The microbial community in the successful startup bioreactor was relatively abundant,while the diversity of microbial community decreased with the increase of feeding SMX.The salt-tolerant and SMX-resistant genera Arcobacter,Thiothrix,Desulfuromusa and Nitrosomonas were gradually enriched and finally played a vital role in converting COD and recycling nitrogen and sulfur.Hence,the present A/O-MBBR reactor with the salt-tolerant functional microbiota achieved efficient removal of pollutants in the presence of low concentration(e.g.,10 mg L−1)SMX.
基金funded by the National Natural Science Foundation of China (No.41210008)the Major State Basic Research Development Program of China (973 Program No.2014CB953701)。
文摘The dust storms from the continent usually affect the abundance and diversity of planktons by supplying trace elements. As such, the response of heterotrophic planktonic bacteria to dusts, nutrients(i.e., nitrogen and phosphorus) or ferrous dosages was investigated in the Kuroshio Extension region of the Northwest Pacific Ocean(NWPO) through on-board incubation experiments during an oceanographic survey in spring 2014. The flow cytometry and 16S rRNA high-throughput sequencing methods were applied to explore the abundance and community structure of bacteria, and the percentage of high nucleic acid bacteria(HNA%). The results showed that the heterotrophic bacteria abundance was low(average 2.55×10^5 cells mL^-1) and subjected to both nitrogen(N) and ferrous(Fe) limitation. Sand-dust deposition observably promoted the activity of heterotrophic planktonic bacteria. The maximum abundance of heterotrophic bacteria was 6.98×10^5 cells mL^-1 in the dust-dosage group, which was 44% higher than the control(P < 0.05). The HNA% in the dust-dosage group was 1.37 times higher than the control(P < 0.05). The activation mechanism was mainly related to the dissolution of N and Fe in the dusts. The relative abundance of genus Winogradskyella was significantly increased by dust deposition while the relative abundance of the genera Tenacibaculum and Hyphomonas was decreased. These variations of bacterial community structure were ascribed to the dissolution of nutrients N and P. Comparing the results of different experimental groups, this study concluded that dust storm improved the abundance of heterotrophic bacteria by dissolution of N and Fe.
基金financially supported by the Shandong Province Science and the Technology Research Projects (No. 2016GSF115004)Fundamental Research Funds for the Central Universities (No. 201964004)
文摘To biologically inhibit the production of highly toxic sulfide in the aquaculture area,one bacterium,designated as Hydrogenovibrio thermophilus strain TT,was isolated from sediment in Jiaozhou Bay,China.The strain was found to be microaerobic mixtrophic,employing both carbon dioxide and organic carbons,e.g.citrate,lactate,glucose,and peptone as carbon sources.When it oxidized the sulfide and thiosulfate,oxygen was the optimal electron acceptor,followed by nitrite and nitrate,which benefited to removal of sulfide under low-oxygen mariculture environment.In addition,the strain TT exhibited remarkable tolerance of sulfide and thiosulfate in seawater,and it was able to oxidize 18.52 mmol L^-1 S^2-in 12 h or 45 mmol L^-1 S2O3^2-in 24 h at initial pH 7.0-9.0,30-40℃.Therefore,this strain showed a quite promising application for biological remediation of sulfide-contaminated mariculture system.
基金supported by the National Key R&D Program of China(No.2018YFD0900805)the Start up Foundation for Introducing Talent of Nanjing Univer-sity of Information Science and Technology。
文摘High salt and low temperature are the bottlenecks for the remove of oil contaminants by enriched crude-oil degrading microbiota in Liaohe Estuarine Wetland(LEW),China.To improve the performance of crude-oil removal,microbiota was further immobilized by two methods,i.e.,sodium alginate(SA),and polyvinyl alcohol and sodium alginate(PVA+SA).Results showed that the crude oil was effectively removed by the enrichment with an average degrading ratio of 19.42-31.45 mg(L d)^(−1).The optimal inoculum size for the n-alkanes removal was 10%and 99.89%.Some members of genera Acinetobacter,Actinophytocola,Aquabac-terium,Dysgonomonas,Frigidibacter,Sphingobium,Serpens,and Pseudomonas dominated in crude-oil degrading microflora.Though the removal efficiency was lower than free bacteria when the temperature was 15℃,SA and PVA+SA immobilization im-proved the resistance to salinity.The composite crude-oil degrading microbiota in this study demonstrated a perspective potential for crude oil removal from surface water under high salinity and low temperature conditions.
基金Funds for the Central Universities of China(No.201964004)the National Natural Science Foundation of China(No.41977315).
文摘Sorption mechanisms of sulfamethazine(SMT)in different pH solutions are complicated.It has not been sufficiently investigated to enhance removal of SMT from alkalescent aqueous solution.In this study,sorption isotherms and kinetics of SMT by corn biochars pyrolyzed at 300℃ and 600℃(300C,600C)under diverse pH conditions were compared.In order to improve the sorption efficiency of SMT from alkalescent aqueous solution,the biochar 300C was modified by acid or base.Different mathematic models were used to describe sorption driving force and sorption process.Results showed that the biochar 300C possessed more amorphous organic carbon and polar functional groups,which led to a higher sorption capacity than biochar 600C.The sorption rate of biochar 300C was greater than 600C under diverse pH as the physisorption of 300C outweighed 600C.The SMT presented stronger hydrophobicity at pH 5 and higher electrostatic repulsion at pH 1 or 8,which resulted in a higher combining capacity of SMT with both biochars at pH 5 than other pH values.In addition,the acid modified biochar had better removal effect on SMT than alkali at pH solution around 8.The research provides a theoretical basis for the removal of SMT from alkalescent aqueous solution.
基金supported by the National Major Project of Water Pollution Control and Management Technology in China (No. 2013ZX07202-007)
文摘The effects of phenanthrene(Phe)on the denitrification activity and denitrifying genes(narG,nirS and nosZ)were evaluated by dose-response experiments in sediments of Dagu River Estuary(DRE)and Jiaozhou Bay(JZB).The results showed that potential denitrification activity(PDA),N2O,NO3−and NO2−reduction rates of both areas were inhibited with an increase of Phe concentrations.The PDA,N2O,NO3−and NO2−reduction rates of both areas was highest and lowest in the control(DRE:0.453,0.427,7.439 and 3.222mgNkg−1 h−1,JZB:0.592,0.555,8.470 and 3.793mgNkg−1 h−1)and highest Phe amended treatments(DRE:0.069,0.001,4.486,and 1.563 mgNkg−1 h−1;JZB:0.114,0.024,5.527 and 2.200 mgNkg−1 h−1).The inhibition rate of PDA was highest,follow by NO2−reduction and then NO3−reduction.Moreover,with the increasing of Phe concentrations,total bacteria count and the abundance of denitrifying genes were decreased.And N2O accumulation was promoted with the addition of Phe for both areas.Based on the comparison of EC50 values,denitrifiers harboring three genes were more sensitive to Phe than PDA,and denitrifiers harboring nirS gene were more sensitive,followed by nosZ gene,and then narG gene.Furthermore,according to correlation analysis,the relative abundance of denitrifying genes was much more positively correlated with PDA,NO3−and NO2−reduction than total bacteria count.In addition,the denitrification activity and total bacteria count in JZB were more inhibited than that of DRE.This study is useful for understanding the impact of Phe pollution on denitrification in estuary and marine sediments,with profound implications for the management of aquatic ecosystems regarding eutrophication(N-removal)and greenhouse effect.
