[Ecological safety regulation of A/DAT-IAT process for municipal wastewater treatment]

Four controlling parameters of A/DAT-IAT process for municipal wastewater treatment, i. e., operation period (T), external recycled rate (R1), internal recycled rate (R2), and mixed liquid suspended solid concentration (MLSS), were studied by orthogonal experiments, and the regular and ecotoxicological indicators of the effluents were examined. The results showed that the optimum conditions of regular indicators removal were T = 3 h, R1 = 20%, R2 = 150%, and MLSS = 5000 mg x L(-1), and the optimum conditions of ecotoxicological indicators removal were T = 3 h, R1 = 20%, R2 = 150%, and MLSS = 3000 mg x L(-1). The reason which caused the difference of the two optimum conditions might be that there were some non-biodegradable organic matters having certain ecological toxic effects and some organic matters whose ecological toxicity increased after hydrolysis and acidification. Adding flocculants and properly choosing controlling parameters were suggested to improve the regular and ecotoxicological indicators of the effluent.