摘要:
焦化废水是一种典型的难降解工业废水,组分复杂,生物毒性高,大多采用生物处理联合物化深度处理的工艺,以满足炼焦化学工业的污染排放标准,但其排水安全性仍然令人担忧。为研究工艺排水安全性,选择发光细菌青海弧菌Q67、稀有鮈鲫(Gobiocypris rasus)血红细胞、活性污泥微生物群落为测试生物,研究了焦化废水及各处理阶段出水的急性毒性和遗传毒性变化,进而识别影响生物毒性的水质因子。焦化废水经过序批式生物膜反应器处理后,出水急性毒性比进水下降71%,遗传毒性下降为90%以上的轻度以下损伤,显示生物强化处理对焦化废水生物毒性有良好的去除作用。生物处理出水再经过深度处理后,则表现出不同的毒性变化:活性炭吸附法对生物急性毒性的消除最佳,但遗传毒性较生物处理出水有所升高;臭氧氧化法不仅水质改善效率差,且最终出水的生物急性毒性与遗传毒性均升高;臭氧催化氧化法对水中残留有机物去除效率较高,但也造成出水急性毒性与遗传毒性的升高。各水样对青海弧菌Q67的急性毒性与有机物、氮等水质指标表现出较强相关性,而遗传毒性与水质指标之间的相关性不显著。研究结果可为评价和改进处理工艺、保障水体生态安全提供参考。
Abstract:
As a typical industrial wastewater containing a lot of refractory and toxic compounds, coking wastewater is often treated by biological and advanced physic-chemical technologies in order to meet the stringent discharge standard of pollutants for coking chemical industry. However, the effluent toxicity is still a pending issue. In this study, Vibrio qinghaiensis sp. Q67, red blood cells of Gobiocypris rasus, and microflora of activated sludge were chosen to test the bio-toxicity of coking wastewater and the effluents from different treatment stages; and water quality factors having significant influence on bio-toxicity were identified. Compared with the influent of coking wastewater, the acute toxicity of the effluent from sequencing biofilm batch reactor (SBBR) was removed by 71%, and over 90% of the genotoxicity was below slight damage level. This improvement indicated that bioaugmented treatment had a remarkable performance on the removal of bio-toxicity. Compared with the SBBR effluent, the final effluents from different advanced treatment exhibited different changes of bio-toxicity. Adsorption by activated carbon resulted in the largest reduction in acute toxicity, but an enhancement in terms of genotoxicity; ozonation had little effect on water quality improvement, and even worse increased the effluent’s acute toxicity and genotoxicity; and activated carbon-mediated ozonation showed better performance on the removal of organic residues, yet increased the effluent’s acute toxicity and genotoxicity as well. The acute toxicity of all the samples measured using the strain Q67 had close positive correlation with the water quality indices of organics, nitrogen, and etc., while the genotoxicity did not correlate with those indices. The results provide a reference for the evaluation and improvement of wastewater treatment process, and a viewpoint for the ecological safety of effluent-receiving water body.
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