Toxicity reduction of municipal wastewater by anaerobic-anoxic-oxic process / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>This study was conducted to optimize the operational parameters of anaerobic-anoxic-oxic (A²/O) processes to reduce the toxicity of municipal wastewater and evaluate its ability to reduce toxicity.</p><p><b>METHODS</b>A luminescent bacterium toxicity bioassay was employed to assess the toxicity of influent and effluent of each reactor in the A²/O system.</p><p><b>RESULTS</b>The optimum operational parameters for toxicity reduction were as follows: anaerobic hydraulic retention time (HRT) = 2.8 h, anoxic HRT = 2.8 h, aerobic HRT = 6.9 h, sludge retention time (SRT) = 15 days and internal recycle ratio (IRR) = 100%. An important toxicity reduction (%) was observed in the optimized A²/O process, even when the toluene concentration of the influent was 120.7 mg·L⁻¹.</p><p><b>CONCLUSIONS</b>The toxicity of municipal wastewater was reduced significantly during the A²/O process. A²/O process can be used for toxicity reduction of municipal wastewater under toxic-shock loading.</p>

Review of Studies on Azo Dyes Decolorization / 微生物学通报

Biological process is an important approach to treat the dye wastewater. The azo dyes decolouration by special azoreductase of different aerobic bacteria and fungi was summarized. Under anaerobic condition, reductive decolourization of azo dyes was carried in the presence of redox mediators which act as electron shuttle. It was also pointed out that azo dye reduction occurred mainly under anaerobic condition. Different electron donor resulted in different decolourization rate. Problems of current biotechnology were analyzed and corresponding measures were discussed.