Safety Evaluation For Wastewater And Reclaimed Water Using A Battery Of Bioassay

With a kind of biological toxicity test methods, the photobacteria toxicity test, the common chlorella growth inhibition test, the zebrafish embryo toxicity test and umu genetic toxicity, comprehensive evaluation of A2O-MBR quality safety of reclaimed water. Using three methods including unit classification method, the potential biological toxicity(PEEP) index method, water quality safety classification method, to evaluate water quality safety, in order to establish an effective biological safety evaluation system and control water quality and pollutant on ecosystem.By optimization of related parameters and steps, established stable and reliable four kinds of biological toxicity test methods. Applicate it to SIYUAN sewage treatment plant A2O-MBR process, with inhibition/death rate, the concentrated/diluted multiples, equivalent concentrations of a variety of methods to impress toxicity Experimental results show that the removal effect of A2 O process is remarkable to acute toxicity, the removal rate can reach 92%, A2 O process can remove genetic toxicity to a certain extent, removal rate is 48%. The simples after MBR and disinfection, removal rate of four kinds of biological toxicity for is varied, and have reduced with different amplitude, especially for embryo toxicity and genetic toxicity increased significantly, acute toxicity of embryo increases 35%, genetic toxicity increased by 19%. After artificial lake system, four kinds of biological toxicity were reduced, especially for genetic toxicity removal effect is remarkable, removal rate can reach 63%.Application of toxic unit classification method, PEEP index method, water quality safety classification method of three methods for a variety of biological toxicity test results to have water safety assessment. Different evaluation methods have different results. With toxic unit classification method of luminescent bacteria, the common chlorella, and zebrafish embryosa three acute toxicity to have comprehensive evaluation. The results shows that the wastewater is slightly toxic, second effluent, effluent 、 MBRdisinfection and outflow of artificial lake are non-toxic; With PEEP index method to evaluate water quality safety for luminescent bacteria toxicity, the result shows that wastewater is medium toxic, second effluent, effluent of MBR-disinfection and outflow of artificial lake are slightly toxic. With water quality safety classification method for the four kinds of biological toxicity, the result shows that the wastewater for class is C, second effluent. effluent of MBR-disinfection for class is B, outflow of artificial lake is A level. Through analyzing the three methods of evaluation results. It finds that water quality safety classification method can more accurate, comprehensive evaluation of water quality safety.The research shows, the A2 O traditional secondary biological treatment and artificial lake near natural ecosystem can effectively remove the acute toxicity and genetic toxicity of water and improve water quality safety. Especially to A2 O secondary biological treatment for acute toxicity, artificial lake near the natural ecological system for genetic toxicity is very significant, and artificial lake near natural ecological system can effectively compensate for defects which A2 O biological treatment is not very effictive to genetic toxicity. Disinfection will cause the increase of water quality toxicity, especially for acute embryo toxicity and genetic toxicity. The water quality safety evaluation result shows that the MBR-disinfection has certain risk, artificial lake water is relatively safe, when directly reuse with MBR-disinfect water, should take measures to ensure quality and water ecological security.