Osmotic distillation(OD) was found to be a coupled process in membrane absorption(MA) for the treatment of high strength ammonia wastewater. As a result, ammonia could not be concentrated in absorption solution(AS) as...Osmotic distillation(OD) was found to be a coupled process in membrane absorption(MA) for the treatment of high strength ammonia wastewater. As a result, ammonia could not be concentrated in absorption solution(AS) as expected. The inhibition of the coupled OD in MA process was investigated as well as various factors affecting the inhibition. The results indicated that the coupled OD can be effectively inhibited by heating concentrated solution and cooling dilute solution. It was also found that experimental minimum inhibition temperature difference(MITD) between concentrated and dilute solutions was different when using polyvinylidene fluoride(PVDF) and polypropylene(PP) membranes respectively, which could be ascribed to material properties, such as OD and membrane distillation(MD) coefficients of the membranes. Experimental MITDs were found to be higher than theoretical MITDs which were calculated using a simplified method.展开更多
[Objective] The treatment effect of inner circulation impinging stream biofilm reactor(ICISBR) on high strength ammonia wastewater was studied.[Method] By means of ICISBR,high strength ammonia wastewater was treated b...[Objective] The treatment effect of inner circulation impinging stream biofilm reactor(ICISBR) on high strength ammonia wastewater was studied.[Method] By means of ICISBR,high strength ammonia wastewater was treated by using corncob as biological carrier,and the effect of C/N and dissolved oxygen(DO) on the removal effect of chemical oxygen demand(COD) and ammonia nitrogen(NH+4-N) were discussed in our paper.[Result] When NH+4-N and DO in effluent water were 200 and 2 mg/L,respectively,the removal effect of COD was not affected obviously whether C/N was 1.0 or 1.5,reaching above 92%;when C/N was 1.5,the average removal rate of COD and NH+4-N were the highest,namely 92.7% and 41.2%,respectively;when C/N was 2.0,the average removal rate of COD and NH+4-N decreased obviously to 20% and 10%;when C/N and NH+4-N were 1.5 and 200 mg/L,DO had little effects on the removal of COD and great effects on the removal of NH+4-N,namely the removal rate of NH+4-N decreased to 17.1% from 46.4% with the reduction of DO concentration from 4 to 1 mg/L.[Conclusion] Our study could provide theoretical basis for the treatment of high strength ammonia wastewater.展开更多
As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people's attention. Catalytic ozonation technology, which involves production of ·OH rad...As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people's attention. Catalytic ozonation technology, which involves production of ·OH radical with strong oxidation ability, is widely used in the treatment of organic-containing wastewater. In this work, MgO-Co3O4 composite metal oxide catalysts prepared with different fabrication conditions have been systematically evaluated and compared in the catalytic ozonation of ammonia(50 mg/L) in water. In terms of high catalytic activity in ammonia decomposition and high selectivity for gaseous nitrogen, the catalyst with MgO-Co3O4 molar ratio 8:2, calcined at 500°C for 3 hr, was the best one among the catalysts we tested, with an ammonia nitrogen removal rate of 85.2% and gaseous nitrogen selectivity of44.8%. In addition, the reaction mechanism of ozonation oxidative decomposition of ammonia nitrogen in water with the metal oxide catalysts was discussed. Moreover, the effect of coexisting anions on the degradation of ammonia was studied, finding that SO2-4 and HCO-3 could inhibit the catalytic activity while CO2-3 and Br-could promote it. The presence of coexisting cations had very little effect on the catalytic ozonation of ammonia nitrogen. After five successive reuses, the catalyst remained stable in the catalytic ozonation of ammonia.展开更多
Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method(SFM) was applied for the complex decomposition and simultaneous removal...Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method(SFM) was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia.The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion.Ammonia was separated from solution as crystalline struvite,and the copper mainly co-precipitated as copper hydroxide together with struvite.Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide.Hydrogen bonding was concluded to be the key factor leading to the co-precipitation.In addition,incorporation of copper ions into the struvite crystal also occurred during the treatment process.展开更多
A full-scale integrated-bioreactor consisting of a suspended zone and an immobilized zone was employed to treat the ordours emitted from a wastewater treatment plant. The inlet concentrations of H,S and NH3 were 1.6-3...A full-scale integrated-bioreactor consisting of a suspended zone and an immobilized zone was employed to treat the ordours emitted from a wastewater treatment plant. The inlet concentrations of H,S and NH3 were 1.6-38.6 mg.m-3 and 0.1 6.7 mg.m-3 respectively, while the steady-state outlet concentrations were reduced to 0-2.8mg.m - for H2S and 0-0.5mg.m for NH3. BothH2SandNH3 were eliminated effectively by the integrated-bioreactor. The removal efficiencies of H2S and NH3 differed between the two zones. Four species of microorganisms related to the degradation of H2S and NH3 were isolated. The characteristics and distributions of the microbes in the bioreactor depended on the inlet concentration of substrates and the micro-environmental conditions in the individual zones. Product analysis indicated that most of the H2S was oxidized into sulfate in the immobilized zone but was dissolved into the liquid phase in the suspended zone. A large amount of NH3 was converted into nitrate and nitrite by nitration in the suspended zone, whereas only a small amount of NH3 was transferred to the aqueous phase mainly by absorption or chemical neutralization in the immobilized zone. Different microbial populations dominated the individual zones, and the major biodegradation products varied accordingly.展开更多
文摘Osmotic distillation(OD) was found to be a coupled process in membrane absorption(MA) for the treatment of high strength ammonia wastewater. As a result, ammonia could not be concentrated in absorption solution(AS) as expected. The inhibition of the coupled OD in MA process was investigated as well as various factors affecting the inhibition. The results indicated that the coupled OD can be effectively inhibited by heating concentrated solution and cooling dilute solution. It was also found that experimental minimum inhibition temperature difference(MITD) between concentrated and dilute solutions was different when using polyvinylidene fluoride(PVDF) and polypropylene(PP) membranes respectively, which could be ascribed to material properties, such as OD and membrane distillation(MD) coefficients of the membranes. Experimental MITDs were found to be higher than theoretical MITDs which were calculated using a simplified method.
基金Supported by Key Technology R & D Program of Jiangxi Province (2010BSA19500)Science and Technology Project of Jiujiang University(09kj12)~~
文摘[Objective] The treatment effect of inner circulation impinging stream biofilm reactor(ICISBR) on high strength ammonia wastewater was studied.[Method] By means of ICISBR,high strength ammonia wastewater was treated by using corncob as biological carrier,and the effect of C/N and dissolved oxygen(DO) on the removal effect of chemical oxygen demand(COD) and ammonia nitrogen(NH+4-N) were discussed in our paper.[Result] When NH+4-N and DO in effluent water were 200 and 2 mg/L,respectively,the removal effect of COD was not affected obviously whether C/N was 1.0 or 1.5,reaching above 92%;when C/N was 1.5,the average removal rate of COD and NH+4-N were the highest,namely 92.7% and 41.2%,respectively;when C/N was 2.0,the average removal rate of COD and NH+4-N decreased obviously to 20% and 10%;when C/N and NH+4-N were 1.5 and 200 mg/L,DO had little effects on the removal of COD and great effects on the removal of NH+4-N,namely the removal rate of NH+4-N decreased to 17.1% from 46.4% with the reduction of DO concentration from 4 to 1 mg/L.[Conclusion] Our study could provide theoretical basis for the treatment of high strength ammonia wastewater.
基金supported the National Natural Science Foundation of China (Nos. 51164014 and 51568023)
文摘As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people's attention. Catalytic ozonation technology, which involves production of ·OH radical with strong oxidation ability, is widely used in the treatment of organic-containing wastewater. In this work, MgO-Co3O4 composite metal oxide catalysts prepared with different fabrication conditions have been systematically evaluated and compared in the catalytic ozonation of ammonia(50 mg/L) in water. In terms of high catalytic activity in ammonia decomposition and high selectivity for gaseous nitrogen, the catalyst with MgO-Co3O4 molar ratio 8:2, calcined at 500°C for 3 hr, was the best one among the catalysts we tested, with an ammonia nitrogen removal rate of 85.2% and gaseous nitrogen selectivity of44.8%. In addition, the reaction mechanism of ozonation oxidative decomposition of ammonia nitrogen in water with the metal oxide catalysts was discussed. Moreover, the effect of coexisting anions on the degradation of ammonia was studied, finding that SO2-4 and HCO-3 could inhibit the catalytic activity while CO2-3 and Br-could promote it. The presence of coexisting cations had very little effect on the catalytic ozonation of ammonia nitrogen. After five successive reuses, the catalyst remained stable in the catalytic ozonation of ammonia.
基金supported by the National Natural Science Foundation of China(No.51204213)the Key Project of Science and Technology of Hunan Province(No.2013WK2007)the Innovation Stimulating Program of Central South University(No.2015CX001)
文摘Heavy metals and ammonia are difficult to remove from wastewater,as they easily combine into refractory complexes.The struvite formation method(SFM) was applied for the complex decomposition and simultaneous removal of heavy metal and ammonia.The results indicated that ammonia deprivation by SFM was the key factor leading to the decomposition of the copper-ammonia complex ion.Ammonia was separated from solution as crystalline struvite,and the copper mainly co-precipitated as copper hydroxide together with struvite.Hydrogen bonding and electrostatic attraction were considered to be the main surface interactions between struvite and copper hydroxide.Hydrogen bonding was concluded to be the key factor leading to the co-precipitation.In addition,incorporation of copper ions into the struvite crystal also occurred during the treatment process.
基金The authors express their sincerely Acknowledgments to ShineWrite and Editage services center of professional editing support for the English revision of the manuscript. This work was financially supported by the National Nature Science Foundation of China (Grant No. 51478456), Scientific Research Foundation of Beijing University of Civil Engineering and Architecture (No. 00331615020) and Beijing Municipal Science and Technology Commission (D 151100005115002).
文摘A full-scale integrated-bioreactor consisting of a suspended zone and an immobilized zone was employed to treat the ordours emitted from a wastewater treatment plant. The inlet concentrations of H,S and NH3 were 1.6-38.6 mg.m-3 and 0.1 6.7 mg.m-3 respectively, while the steady-state outlet concentrations were reduced to 0-2.8mg.m - for H2S and 0-0.5mg.m for NH3. BothH2SandNH3 were eliminated effectively by the integrated-bioreactor. The removal efficiencies of H2S and NH3 differed between the two zones. Four species of microorganisms related to the degradation of H2S and NH3 were isolated. The characteristics and distributions of the microbes in the bioreactor depended on the inlet concentration of substrates and the micro-environmental conditions in the individual zones. Product analysis indicated that most of the H2S was oxidized into sulfate in the immobilized zone but was dissolved into the liquid phase in the suspended zone. A large amount of NH3 was converted into nitrate and nitrite by nitration in the suspended zone, whereas only a small amount of NH3 was transferred to the aqueous phase mainly by absorption or chemical neutralization in the immobilized zone. Different microbial populations dominated the individual zones, and the major biodegradation products varied accordingly.