To understand the anaerobic degradation pathway of domestic sewage,three lab-scale upflow anaerobic sludge blanked reactors (UASB) were employed to study the degradation pathway of different particle size and the effe...To understand the anaerobic degradation pathway of domestic sewage,three lab-scale upflow anaerobic sludge blanked reactors (UASB) were employed to study the degradation pathway of different particle size and the effect of temperature on this process.Under the operation conditions of the hydraulic retention time of 24 h,the MLVSS of approximate 11200 mg·L-1 and the water temperature at 10,15 and 20℃,the overall degradation pathway of soluble fraction was characterized according to zero-order kinetics.As for the colloidal fraction (between 0.45 and 4.5 μm),the degradation processes followed a first-order kinetic,and should firstly disintegrated into soluble fraction before finally degrading.In contrast,suspended solids (bigger than 4.5 μm) degraded to soluble and colloidal fractions according to first-order kinetics,and the colloidal fraction originating from suspended solids further degraded into soluble fraction which had the same degradation kinetics as the original soluble fraction.There existed the difference of temperature effect on different fraction degradation.Under the temperature at 20,15 and 10 ℃,the first-order rate constant of suspended solids depredating into collide was 4.97,3.01 and 1.01 d-1 respectively.Whereas the degradation of collide to soluble fraction was slightly affected by the temperature change.On the other hand,the zero-order degradation rate constant of soluble fraction was 0.26,0.18 g and 0.12 gCOD·gVSS-1d-1,respectively.展开更多
Different hydraulic retention times(HRTs)were tested in a mixed anoxic/oxic(A/O)system at 5C and 10C to investigate the effects of HRT and carrier on nitrogen removal in wastewater at low temperatures.The results show...Different hydraulic retention times(HRTs)were tested in a mixed anoxic/oxic(A/O)system at 5C and 10C to investigate the effects of HRT and carrier on nitrogen removal in wastewater at low temperatures.The results showed that the addition of the fillers improved the treatment effect of each index in the system.With an optimal HRT of 7.5 h at 5C,the removal efficiencies of NHþ4-N and total nitrogen(TN)reached 91.2%and 75.6%,respectively.With an HRT of 6 h at 10C,the removal efficiencies of NHþ4-N and TN were 96.7%and 82.9%,respectively.The results of high-throughput sequencing showed that the addition of the suspended carriers in the aerobic zone could improve the treatment efficiency of nitrogen at low temperatures.The microbial analysis indicated that the addition of the suspended carriers enhanced the enrichment of nitrogen removal bacteria.Nitrospira,Nitrotoga,and Nitrosomonas were found to be the bacteria responsible for nitrification,and their relative concentrations on the biofilm at 5C and 10C accounted for 98.11%,92.79%,and 69.98%of all biological samples,respectively.展开更多
The metallurgical sewage has very complex component and a significant environmental perniciousness and needs high treatment costs. In addition, too much low-temperature waste heat is emitted owing to the lack of suita...The metallurgical sewage has very complex component and a significant environmental perniciousness and needs high treatment costs. In addition, too much low-temperature waste heat is emitted owing to the lack of suitable users. Considering these concerns, a low-temperature-driven pretreatment method via vacuum distillation was proposed to treat the sewage from the metallurgical production. It uses the sensible heat carried by low-temperature exhausted gases to drive the distillation of sewage. The distilled water can be reused into the process as new water supply, while the enriched wastewater is discharged into the sewage treatment center for subsequent treatment. Converter dust removal sewage was chosen to perform an experimental observation. The variations of chemical oxygen demand, ammonia nitrogen, suspended solids, electrical conductivity, and pH of the condensate under different vacuum degrees and evaporation rates were mainly investigated. It can be found that the quality of the condensate gets better under certain conditions, which validates the feasibility of the proposed approach. Furthermore, by comprehensively analyzing the water quality indices and their influencing factors, the optimal vacuum degree was suggested to be controlled between 0.07 and 0.09 MPa, and the best evaporation rate was between 40 and 60%.展开更多
基金Sponsored by the National Natural Science Foundation of China (Grant No.51078102)the National Water Special Project (Grant No.2008ZX07207-005-02)the Science and Technology Research Project of Education Department of Heilongjiang Province(Grant No.11551370)
文摘To understand the anaerobic degradation pathway of domestic sewage,three lab-scale upflow anaerobic sludge blanked reactors (UASB) were employed to study the degradation pathway of different particle size and the effect of temperature on this process.Under the operation conditions of the hydraulic retention time of 24 h,the MLVSS of approximate 11200 mg·L-1 and the water temperature at 10,15 and 20℃,the overall degradation pathway of soluble fraction was characterized according to zero-order kinetics.As for the colloidal fraction (between 0.45 and 4.5 μm),the degradation processes followed a first-order kinetic,and should firstly disintegrated into soluble fraction before finally degrading.In contrast,suspended solids (bigger than 4.5 μm) degraded to soluble and colloidal fractions according to first-order kinetics,and the colloidal fraction originating from suspended solids further degraded into soluble fraction which had the same degradation kinetics as the original soluble fraction.There existed the difference of temperature effect on different fraction degradation.Under the temperature at 20,15 and 10 ℃,the first-order rate constant of suspended solids depredating into collide was 4.97,3.01 and 1.01 d-1 respectively.Whereas the degradation of collide to soluble fraction was slightly affected by the temperature change.On the other hand,the zero-order degradation rate constant of soluble fraction was 0.26,0.18 g and 0.12 gCOD·gVSS-1d-1,respectively.
基金supported by the National Natural Science Foundation of China(Grants No.51978233 and 52000057)the China Postdoctoral Science Foundation(Grant No.2020M680844).
文摘Different hydraulic retention times(HRTs)were tested in a mixed anoxic/oxic(A/O)system at 5C and 10C to investigate the effects of HRT and carrier on nitrogen removal in wastewater at low temperatures.The results showed that the addition of the fillers improved the treatment effect of each index in the system.With an optimal HRT of 7.5 h at 5C,the removal efficiencies of NHþ4-N and total nitrogen(TN)reached 91.2%and 75.6%,respectively.With an HRT of 6 h at 10C,the removal efficiencies of NHþ4-N and TN were 96.7%and 82.9%,respectively.The results of high-throughput sequencing showed that the addition of the suspended carriers in the aerobic zone could improve the treatment efficiency of nitrogen at low temperatures.The microbial analysis indicated that the addition of the suspended carriers enhanced the enrichment of nitrogen removal bacteria.Nitrospira,Nitrotoga,and Nitrosomonas were found to be the bacteria responsible for nitrification,and their relative concentrations on the biofilm at 5C and 10C accounted for 98.11%,92.79%,and 69.98%of all biological samples,respectively.
基金This work was sponsored by the National Natural Science Foundation of China （51734004, 21561122001）, the China Scholarship Council （201702660037） and the Fundamental Research Funds for the China Central Universities （N162504011）.
文摘The metallurgical sewage has very complex component and a significant environmental perniciousness and needs high treatment costs. In addition, too much low-temperature waste heat is emitted owing to the lack of suitable users. Considering these concerns, a low-temperature-driven pretreatment method via vacuum distillation was proposed to treat the sewage from the metallurgical production. It uses the sensible heat carried by low-temperature exhausted gases to drive the distillation of sewage. The distilled water can be reused into the process as new water supply, while the enriched wastewater is discharged into the sewage treatment center for subsequent treatment. Converter dust removal sewage was chosen to perform an experimental observation. The variations of chemical oxygen demand, ammonia nitrogen, suspended solids, electrical conductivity, and pH of the condensate under different vacuum degrees and evaporation rates were mainly investigated. It can be found that the quality of the condensate gets better under certain conditions, which validates the feasibility of the proposed approach. Furthermore, by comprehensively analyzing the water quality indices and their influencing factors, the optimal vacuum degree was suggested to be controlled between 0.07 and 0.09 MPa, and the best evaporation rate was between 40 and 60%.
