Phytoplankton and environmental variables were measured monthly from July 2009 to August 2011 in the Maixi River from the estuary to Baihua Reservoir in the Maotiao River catchment, southwestern China, to understand p...Phytoplankton and environmental variables were measured monthly from July 2009 to August 2011 in the Maixi River from the estuary to Baihua Reservoir in the Maotiao River catchment, southwestern China, to understand phytoplankton community structure and environmental factors. The relationship between phytoplankton community structure and environmental factors including hydrological, meteorological, physical, and chemical variables were explored using multivariate analysis. A total of 81 taxa of phytoplankton were identified, which were mainly composed of chlorophyta, bacillariophyta, and cyanobacteria. The phytoplankton community was dominated by Pseudanabaena limnetica during summer and fall and by Cyclotella meneghiniana during winter and spring. The abundance of phytoplankton ranged from 0.24~ 104 cells/L to 33.45x 106 cells/L, with the minimum occurring during February 2010 and the maximum during July 2009. The phytoplankton community was dominated mainly by cyanobacteria from April to September, and by bacillariophyta and pyrrophyta from October to March. Canonical correspondence analysis showed that temperature, pH values, and orthophosphate were the most important driving factors regulating the composition and dynamics of the phytoplankton community in the estuary. Cyanobacteria and euglenophyta abundance and biomass were affected mainly by temperature and pH values, while most chlorophyta and bacillariophyta were influenced by the concentrations of nutrients.展开更多
A membrane bioreactor （MBR） was established for treating harbor oily wastewater. It showed good removal performance for chemical oxygen demand （COD）, oil content, suspended solids （SS）, and other pollutants. How...A membrane bioreactor （MBR） was established for treating harbor oily wastewater. It showed good removal performance for chemical oxygen demand （COD）, oil content, suspended solids （SS）, and other pollutants. However, serious membrane fouling occurred. It was recognized that the extracellular polymeric substances （EPS） accumulated on the membrane surface, especially the proteins, were of great importance for the transmembrane pressure （TMP） increment and membrane fouling. The MBR was optimized via improving aeration rate and reducing the ratio of Ar/Ad （At and Ad are the cross-sectional areas of the riser and the downcomer of the MBR）. The increasing rate of TMP was slowed, indicating that the optimization strategy could effectively mitigate membrane fouling. Microbial community evolution was monitored and analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE）, cloning, and sequencing of 16S ribosomal ribonucleic acid （rRNA） fragments. Results revealed that low community shift occurred during the whole operational period. Geobacter sp. and Rhodocyclales sp., which have also been identified by other studies in a petroleum refinery wastewater MBR or an infiltration basin receiving highway runoff, dominated in the MBR system throughout. Comamonas sp. was thought to accommodate the lower aeration rate in this study, while Rhodocyclales sp. preferred the higher aeration rate. In addition, during the operational time under high organic loading rate, a few species were present in abundance, and may have been responsible for the good removal performance at this time.展开更多
基金Supported by the National Natural Science Foundation of China(No.411063005)the National Basic Research Program of China(973 Program)(No.2012CB426506)the Science and Technology Committee of Guizhou Foundation(Nos.[2011]7028,[2012]7021)
文摘Phytoplankton and environmental variables were measured monthly from July 2009 to August 2011 in the Maixi River from the estuary to Baihua Reservoir in the Maotiao River catchment, southwestern China, to understand phytoplankton community structure and environmental factors. The relationship between phytoplankton community structure and environmental factors including hydrological, meteorological, physical, and chemical variables were explored using multivariate analysis. A total of 81 taxa of phytoplankton were identified, which were mainly composed of chlorophyta, bacillariophyta, and cyanobacteria. The phytoplankton community was dominated by Pseudanabaena limnetica during summer and fall and by Cyclotella meneghiniana during winter and spring. The abundance of phytoplankton ranged from 0.24~ 104 cells/L to 33.45x 106 cells/L, with the minimum occurring during February 2010 and the maximum during July 2009. The phytoplankton community was dominated mainly by cyanobacteria from April to September, and by bacillariophyta and pyrrophyta from October to March. Canonical correspondence analysis showed that temperature, pH values, and orthophosphate were the most important driving factors regulating the composition and dynamics of the phytoplankton community in the estuary. Cyanobacteria and euglenophyta abundance and biomass were affected mainly by temperature and pH values, while most chlorophyta and bacillariophyta were influenced by the concentrations of nutrients.
基金supported by the Science and Technology Project of the Ministry of Transport(No.2011-329-224-330)the National Nonprofit Institute Research Grants of Tianjin Research Institute for Water Transport Engineering(Nos.TKS100216,TKS130206,and TKS160215),China
文摘A membrane bioreactor （MBR） was established for treating harbor oily wastewater. It showed good removal performance for chemical oxygen demand （COD）, oil content, suspended solids （SS）, and other pollutants. However, serious membrane fouling occurred. It was recognized that the extracellular polymeric substances （EPS） accumulated on the membrane surface, especially the proteins, were of great importance for the transmembrane pressure （TMP） increment and membrane fouling. The MBR was optimized via improving aeration rate and reducing the ratio of Ar/Ad （At and Ad are the cross-sectional areas of the riser and the downcomer of the MBR）. The increasing rate of TMP was slowed, indicating that the optimization strategy could effectively mitigate membrane fouling. Microbial community evolution was monitored and analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE）, cloning, and sequencing of 16S ribosomal ribonucleic acid （rRNA） fragments. Results revealed that low community shift occurred during the whole operational period. Geobacter sp. and Rhodocyclales sp., which have also been identified by other studies in a petroleum refinery wastewater MBR or an infiltration basin receiving highway runoff, dominated in the MBR system throughout. Comamonas sp. was thought to accommodate the lower aeration rate in this study, while Rhodocyclales sp. preferred the higher aeration rate. In addition, during the operational time under high organic loading rate, a few species were present in abundance, and may have been responsible for the good removal performance at this time.
