| In this study the luminescent bacteria Virbrio qinghaiensis sp.-Q67 was used to assess the acute toxicity of wastewater from different treatment processes of the oxidation ditch plants. The impact factors of detection were also been analyzed. The results indicated that all samples were showed stimulating effects when the acute toxicity of wastewater samples were tested immediately. When the acute toxicity was tested after one day, some samples showed inhibiting effects. When the samples of wastewater were treated with 0.45 μm membrane filtration, the acute toxicity could be monitored authentically and accurately. After sterilization, the acute toxicity of wastewater was stable during in the days of depositing. Organic material in wastewater could be enriched with solid-phase extraction. It could be well used to monitor ecotoxicity of organic substances in wastewater treatment units. The efficient concentration (EC50) values of progresses were as follows. The EC50 values of raw water, primary settler effluent, oxidation ditch effluent, secondary settler effluent and UV disinfection effluent were 11.44, 11.96, 21.05, 16.06 and 15.17, respectively. The ecotoxicity of wastewater in the plant was removed by the process of oxidation ditch but the removal was very limited. |
