title: Reduction in toxicity of wastewater from three wastewater treatment plants to alga (Scenedesmus obliquus) in northeast China.
abstract: 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.
authors.affiliation: Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024, China. Electronic address: yzhang@dlut.edu.cn.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, No. 2 Linggong Road, Ganjingzi District, Dalian 116024, China.
authors.forename: Jiti
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Faculty of Environment and Information Sciences, Yokohama National University, 79 7 Tokiwadai, Hodogaya-ku, Yokohama, Kanagawa 240 8501, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Masunaga
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 73 Huanghe Road, Nan Gang District, Harbin 150090, China. Electronic address: mafang@hit.edu.cn.
authors.forename: Fang
authors.initials: F
authors.lastname: Ma
mesh_terms: D002452:Cell Count; D002681:China; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D004787:Environmental Pollution / Q000009:adverse effects*; D044444:Scenedesmus / Q000187:drug effects* / Q000378:metabolism; D012722:Sewage; D013482:Superoxide Dismutase / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D002734:Chlorophyll; D000077194:Chlorophyll A; D012722:Sewage; D013482:Superoxide Dismutase; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Activated sludge; Chlorophyll-A; Linpor system; Membrane integrity; SBR; SOD activity