Subtropical climatic conditions can contribute to the death of the aerial parts of constructed wetland plants in winter. This presents a barrier to the widespread application of constructed wetland and is an issue tha...Subtropical climatic conditions can contribute to the death of the aerial parts of constructed wetland plants in winter. This presents a barrier to the widespread application of constructed wetland and is an issue that urgently needs to be solved. Three contrasting experi- ments, the plant-intercropping model （A）, the warm- seasonal plant model （B）, and the non-plant model （C）, were studied in terms of their efficiency in removing pollutants, and the change in root structure of plants in the plant-intercropping model within the vertical-flow con- structed wetlands. The results indicate that model A was able to solve the aforementioned problem. Overall, average removal rates of three pollutants （CODcr, total nitrogen （TN） and total phosphorous （TP）） using model A were significantly higher than those obtained using models B and C （P 〈 0.01）. Moreover, no significant differences in removal rates of the three pollutants were detected between A and B during the higher temperature part of the year （P〉 0.05）. Conversely, removal rates of the three pollutants were found to be significantly higher using model A than those observed using model B during the lower temperature part of the year （P 〈 0.01）. Furthermore, the morphologies and internal structures of plant roots further demonstrate that numerous white roots, whose distribution in soil was generally shallow, extend further under model A. The roots of these aquatic plants have an aerenchyma structure composed of parenchyma cells, therefore, roots of the cold-seasonal plants with major growth advantages used in A were capable of creating a more favorable vertical-flow constructed wetlands media- microenvironment. In conclusion, the plant-intercropping model （A） is more suitable for use in the cold environment experienced by constructed wetland during winter.展开更多
This paper reports a comparative evaluation between 2 kinetic models for predicting nitrification and biodegradable organics(BOD5)removal rates in 5 vertical flow(VF)wetland systems,that received strong wastewaters(i....This paper reports a comparative evaluation between 2 kinetic models for predicting nitrification and biodegradable organics(BOD5)removal rates in 5 vertical flow(VF)wetland systems,that received strong wastewaters(i.e.tannery,textile and municipal effluents).The models were formulated by combining first order and Monod kinetics,with continuous-stirred tank reactor(CSTR)flow approach.The performance of the 2 models had been evaluated with3 statistical parameters:coefficient of determination(R2),relative root mean square error(RRMSE),and model efficiency(ME).The statistical parameters indicated better performance of the Monod CSTR model(over first order CSTR approach),for correlating ammoniacal nitrogen(NH4+—N)and BOD5removal profiles across VF systems.Higher Monod coefficient values(from Monod CSTR model)coincided with greater input NH4+—N and BOD5loading,and experimentally measured removal rate(g/(m2·d))values.Such trends indicate that NH4+—N and BOD5removals in the VF systems were mainly achieved via biological routes.On the other hand,the rate constants(from the first order CSTR model)did not exhibit such correlations(of Monod coefficients),elucidating their inefficiencies in capturing overall removal mechanisms.The interference of organics removal on nitrification process(in VF wetlands)was identified through Monod coefficients.The deviation between NH4+—N and BOD5Monod coefficients imply incorporation of both coefficients,for calculating the area of a single VF bed.Overall,closer performance of the Monod CSTR model for predicting NH4+—N and BOD5removals indicate its potential application,as a design tool for VF systems.展开更多
Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was develope...Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was developed to research the effects of macrophytes commonly employed in CWs,Canna indica,Acorus calamus,and Ipomoea aquatica,on decontamination and electricity production in the system.Because of the different root types and amounts of oxygen released by the roots,the rates of chemical oxygen demand(COD) and ammonium nitrogen(NH4^+-N) removal from the swine wastewater differed as well.In the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,the COD removal rates were 80.20%,88.07%,84.70%,and 82.20%,respectively,and the NH4+-N removal rates were 49.96%,75.02%,70.25%,and 68.47%,respectively.The decontamination capability of the Canna indica system was better than those of the other systems.The average output voltages were 520±42,715±20,660±27,and 752±26 mV for the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,respectively,and the maximum power densities were 0.2230,0.4136,0.3614,and0.4964 W/m^3,respectively.Ipomoea aquatica had the largest effect on bioelectricity generation promotion.In addition,electrochemically active bacteria,Geobacter and Desulfuromonas,were detected in the anodic biofilm by high-throughput sequencing analysis,and Comamonas(Proteobacteria),which is widely found in MFCs,was also detected in the anodic biofilm.These results confirmed the important role of plants in IVCW-MFCs.展开更多
文摘Subtropical climatic conditions can contribute to the death of the aerial parts of constructed wetland plants in winter. This presents a barrier to the widespread application of constructed wetland and is an issue that urgently needs to be solved. Three contrasting experi- ments, the plant-intercropping model （A）, the warm- seasonal plant model （B）, and the non-plant model （C）, were studied in terms of their efficiency in removing pollutants, and the change in root structure of plants in the plant-intercropping model within the vertical-flow con- structed wetlands. The results indicate that model A was able to solve the aforementioned problem. Overall, average removal rates of three pollutants （CODcr, total nitrogen （TN） and total phosphorous （TP）） using model A were significantly higher than those obtained using models B and C （P 〈 0.01）. Moreover, no significant differences in removal rates of the three pollutants were detected between A and B during the higher temperature part of the year （P〉 0.05）. Conversely, removal rates of the three pollutants were found to be significantly higher using model A than those observed using model B during the lower temperature part of the year （P 〈 0.01）. Furthermore, the morphologies and internal structures of plant roots further demonstrate that numerous white roots, whose distribution in soil was generally shallow, extend further under model A. The roots of these aquatic plants have an aerenchyma structure composed of parenchyma cells, therefore, roots of the cold-seasonal plants with major growth advantages used in A were capable of creating a more favorable vertical-flow constructed wetlands media- microenvironment. In conclusion, the plant-intercropping model （A） is more suitable for use in the cold environment experienced by constructed wetland during winter.
文摘This paper reports a comparative evaluation between 2 kinetic models for predicting nitrification and biodegradable organics(BOD5)removal rates in 5 vertical flow(VF)wetland systems,that received strong wastewaters(i.e.tannery,textile and municipal effluents).The models were formulated by combining first order and Monod kinetics,with continuous-stirred tank reactor(CSTR)flow approach.The performance of the 2 models had been evaluated with3 statistical parameters:coefficient of determination(R2),relative root mean square error(RRMSE),and model efficiency(ME).The statistical parameters indicated better performance of the Monod CSTR model(over first order CSTR approach),for correlating ammoniacal nitrogen(NH4+—N)and BOD5removal profiles across VF systems.Higher Monod coefficient values(from Monod CSTR model)coincided with greater input NH4+—N and BOD5loading,and experimentally measured removal rate(g/(m2·d))values.Such trends indicate that NH4+—N and BOD5removals in the VF systems were mainly achieved via biological routes.On the other hand,the rate constants(from the first order CSTR model)did not exhibit such correlations(of Monod coefficients),elucidating their inefficiencies in capturing overall removal mechanisms.The interference of organics removal on nitrification process(in VF wetlands)was identified through Monod coefficients.The deviation between NH4+—N and BOD5Monod coefficients imply incorporation of both coefficients,for calculating the area of a single VF bed.Overall,closer performance of the Monod CSTR model for predicting NH4+—N and BOD5removals indicate its potential application,as a design tool for VF systems.
基金supported by the Science and Technology Project of the Education Department of Jiangxi Province of China (No.170688).
文摘Plants constitute a major element of constructed wetlands(CWs).In this study,a coupled system comprising an integrated vertical flow CW(IVCW) and a microbial fuel cell(MFC) for swine wastewater tre atment was developed to research the effects of macrophytes commonly employed in CWs,Canna indica,Acorus calamus,and Ipomoea aquatica,on decontamination and electricity production in the system.Because of the different root types and amounts of oxygen released by the roots,the rates of chemical oxygen demand(COD) and ammonium nitrogen(NH4^+-N) removal from the swine wastewater differed as well.In the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,the COD removal rates were 80.20%,88.07%,84.70%,and 82.20%,respectively,and the NH4+-N removal rates were 49.96%,75.02%,70.25%,and 68.47%,respectively.The decontamination capability of the Canna indica system was better than those of the other systems.The average output voltages were 520±42,715±20,660±27,and 752±26 mV for the unplanted,Canna indica,Acorus calamus,and Ipomoea aquatica systems,respectively,and the maximum power densities were 0.2230,0.4136,0.3614,and0.4964 W/m^3,respectively.Ipomoea aquatica had the largest effect on bioelectricity generation promotion.In addition,electrochemically active bacteria,Geobacter and Desulfuromonas,were detected in the anodic biofilm by high-throughput sequencing analysis,and Comamonas(Proteobacteria),which is widely found in MFCs,was also detected in the anodic biofilm.These results confirmed the important role of plants in IVCW-MFCs.
