Keywords: 
• DAT-IAT process /
• A/DAT-IAT process /
• flocculation /
• ecotoxicology indicators /
• regular indicators

Abstract: Optimum conditions of regular indicators removal and ecotoxicology indicators reduction of municipal wastewater treated by DAT-IAT process and A/DAT-IAT process were studied by orthogonal experiments.Results showed that in the same orthogonal experimental process, the effluents COD under the optimum COD removal conditions were better than that under the optimum ecotoxicity reduction conditions, but the effluents ecotoxicity of the former were higher than that of the latter.Because of hydrolysis-acidification, both COD and ecotoxicity of A/DAT-IAT process were better than those of DAT-IAT process, and the recycle energy demand was lower than DAT-IAT process, but the effluent COD still could not meet the discharge standard. Flocculation precipitation method was used to reduce the gross of COD in the influents, and the dose with the lowest aluminum residual was applied to reduce the effluent ecological risk. Results showed that under the optimum COD removal conditions, the processes with flocculation precipitation pretreatment had better COD removal effects than the processes without pretreatment. The effluents COD of flocculation-A/DAT-IAT process was 104.46 mg/L under the optimum COD removal conditions, and it attained the discharge standard. Under the optimum ecotoxicology reduction conditions, though the effluents ecotoxicology of the flocculation precipitation pretreatment processes were higher than that of the processes without pretreatment, the gross of pollutants removed remarkably. Compared with DAT-IAT process, the flocculation-A/DAT-IAT process could control ecotoxicology and guarantee the ecosafety effectively as well as the reduction of contamination was achieved remarkably.