Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. S...Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen （DO） concentration. There was a programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.展开更多
The contaminant of herbicide clopyralid(3,6-dichloro-2-pyridine-carboxylic acid,CLP)poses a potential threat to the ecological system.However,there is a general lack of research devoted to the perturbation of CLP to t...The contaminant of herbicide clopyralid(3,6-dichloro-2-pyridine-carboxylic acid,CLP)poses a potential threat to the ecological system.However,there is a general lack of research devoted to the perturbation of CLP to the bio-denitrification process,and its biological response mechanism remains unclear.Herein,long-term exposure to CLP was systematically investigated to explore its influences on denitrification performance and dynamic microbial responses.Results showed that low-concentration of CLP(<15 mg/L)caused severe nitrite accumulation initially,while higher concentrations(35e60 mg/L)of CLP had no further effect after long-term acclimation.The mechanistic study demonstrated that CLP reduced nitrite reductase(NIR)activity and inhibited metabolic activity(carbon metabolism and nitrogen metabolism)by causing oxidative stress and membrane damage,resulting in nitrite accumulation.However,after more than 80 days of acclimation,almost no nitrite accumulation was found at 60 mg/L CLP.It was proposed that the secretion of extracellular polymeric substances(EPS)increased from 75.03 mg/g VSS at 15 mg/L CLP to 109.97 mg/g VSS at 60 mg/L CLP,which strengthened the protection of microbial cells and improved NIR activity and metabolic activities.Additionally,the biodiversity and richness of the microbial community experienced a U-shaped process.The relative abundance of denitrification-and carbon metabolism-associated microorganisms decreased initially and then recovered with the enrichment of microorganisms related to the secretion of EPS and N-acyl-homoserine lactones(AHLs).These microorganisms protected microbe from toxic substances and regulated their interactions among interand intra-species.This study revealed the biological response mechanism of denitrification after successive exposure to CLP and provided proper guidance for analyzing and treating herbicide-containing wastewater.展开更多
基金the National Key Project of Scientific and Technical Supporting Program of Ministry of Science and Technology ofChina(2006BAC19B03)Academic Human Resources Development in Institutions of Higher Leading under the Jurisdiction ofBeijing Municipalitythe Specialized Research Fund for the Doctoral Program of Higher Education of China(20060005002).
文摘Sequence hybrid biological reactor （SHBR） was proposed, and some key control parameters were investigated for nitrogen removal from wastewater by simultaneous nitrification and denitrification （SND） via nitrite. SND via nitrite was achieved in SHBR by controlling demand oxygen （DO） concentration. There was a programmed decrease of the DO from 2.50 mg·L^-1 to 0.30 mg·L^-1, and the average nitrite accumulation rate （NAR） was increased from 16.5% to 95.5% in 3 weeks. Subsequently, further increase in DO concentration to 1.50 mg·L^-1 did not destroy the partial nitrification to nitrite. The results showed that limited air flow rate to cause oxygen deficiency in the reactor would eventually induce only nitrification to nitrite and not further to nitrate. Nitrogen removal efficiency was increased with the increase in NAR, that is, NAR was increased from 60% to 90%, and total nitrogen removal efficiency was increased from 68% to 85%. The SHBR could tolerate high organic loading rate （OLR）, COD and ammonia-nitrogen removal efficiency were greater than 92% and 93.5%, respectively,, and it even operated under low DO concentration （0.5 mg·L^-1） and maintained high OLR （4.0 kg COD·m^-3·d^-1）. The presence of biofilm positively affected the activated sludge settling capability, and sludge volume index （SVI） of activated sludge in SHBR never hit more than 90 ml·L^-1 throughout the experiments.
基金the National Natural Science Foundation of China(Grant No.52000134)China Postdoctoral Science Foundation(No.2020M680894)+2 种基金Tianjin Science and Technology Program(No.21YDTPJC00700)Natural Science Foundation of Tianjin Science and Technology Correspondent Project(No.19JCQNJC07800)Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(No.TSBICIP-CXRC-007).
文摘The contaminant of herbicide clopyralid(3,6-dichloro-2-pyridine-carboxylic acid,CLP)poses a potential threat to the ecological system.However,there is a general lack of research devoted to the perturbation of CLP to the bio-denitrification process,and its biological response mechanism remains unclear.Herein,long-term exposure to CLP was systematically investigated to explore its influences on denitrification performance and dynamic microbial responses.Results showed that low-concentration of CLP(<15 mg/L)caused severe nitrite accumulation initially,while higher concentrations(35e60 mg/L)of CLP had no further effect after long-term acclimation.The mechanistic study demonstrated that CLP reduced nitrite reductase(NIR)activity and inhibited metabolic activity(carbon metabolism and nitrogen metabolism)by causing oxidative stress and membrane damage,resulting in nitrite accumulation.However,after more than 80 days of acclimation,almost no nitrite accumulation was found at 60 mg/L CLP.It was proposed that the secretion of extracellular polymeric substances(EPS)increased from 75.03 mg/g VSS at 15 mg/L CLP to 109.97 mg/g VSS at 60 mg/L CLP,which strengthened the protection of microbial cells and improved NIR activity and metabolic activities.Additionally,the biodiversity and richness of the microbial community experienced a U-shaped process.The relative abundance of denitrification-and carbon metabolism-associated microorganisms decreased initially and then recovered with the enrichment of microorganisms related to the secretion of EPS and N-acyl-homoserine lactones(AHLs).These microorganisms protected microbe from toxic substances and regulated their interactions among interand intra-species.This study revealed the biological response mechanism of denitrification after successive exposure to CLP and provided proper guidance for analyzing and treating herbicide-containing wastewater.
