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The toxicity of municipal wastewater to the receiving water bodies is still unknown, due to the lack of regulated toxicity based index for wastewater discharge in China. Our study aims at gaining insight into the acute toxic effects of local municipal wastewater on alga, Scenedesmus obliquus . Four endpoints, i.e. cell density, chlorophyll-A concentration, superoxide dismutase (SOD) activity and cell membrane integrity, of alga were analyzed to characterize the acute toxicity effects of wastewater from municipal wastewater treatment plants (WWTPs) with different treatment techniques: sequencing batch reactor (SBR), Linpor and conventional activated sludge. Influent and effluent from each treatment stage in these three WWTPs were sampled and evaluated for their acute toxicity. Our results showed that all three techniques can completely affect the algal chlorophyll-A synthesis stimulation effects of influent; the algal cell growth stimulation effect was only completely removed by the secondary treatment process in conventional activated sludge technique; toxic effects on cell membrane integrity of two influents from WWTPs with SBR and conventional activated sludge techniques were completely removed; the acute toxicity on SOD activity was partially reduced in SBR and conventional activated sludge techniques while not significantly reduced by Linpor system. As to the disinfection unit, NaClO disinfection enhanced wastewater toxicity dramatically while UV radiation had no remarkable influence on wastewater toxicity. Our results illustrated that SOD activity and chlorophyll-A synthesis were relatively sensitive to municipal wastewater toxicity. Our results would aid to understand the acute toxicity of municipal wastewater, as well as the toxicity removal by currently utilized treatment techniques in China. [ABSTRACT FROM AUTHOR]

To further promote the water pollution control of Northeast China, to ensure the water environmental safety of Songhua river and Liaohe river, and to accelerate the harmonious development of economy, society and environment in Northeast China, the performances of 32 typical municipal wastewater treatment plants (MWWTPs) located in 13 key cities of Liaoning, Jilin and Heilongjiang were investigated and analyzed. General problems generated in the operation and management of these MWWTPs were found out, and the corresponding strategies for their stable performances were proposed. These provide guidance from the perspective of water pollution control for the sustainable development and benign circulation of the economy in Northeast China. [ABSTRACT FROM AUTHOR]