石化废水处理过程中活性污泥毒性变化

Changes of the toxicity of petrochemical wastewater to activated sludge along the treatment processes

考察了某石化园区废水从进入污水处理厂到到达好氧生物处理单元之前,各级工艺处理后废水对活性污泥的毒性的变化情况,通过活性污泥耗氧速率抑制效应、脱氢酶活性抑制效应和发光细菌急性毒性3种指标表征石化废水的活性污泥毒性,测定了沿程各节点废水的三维荧光光谱,并解析了石化废水对活性污泥的毒性与其荧光光谱特征之间的相关性.结果表明,石化废水对好氧生物处理工艺中硝化细菌耗氧速率的抑制率达50%~60%,经过好氧生物处理单元之前的各级处理后,抑制作用仍然在30%左右.在沿程各处理工艺中,水解酸化与A段缺氧处理对毒性削减作用相对明显.比较3种毒性表征方法的结果,耗氧速率法较适合评价石化废水对活性污泥的毒性.各水样的荧光峰集中在λ_(ex)/λ_(em)=200~300/250~400nm区域,其中峰C(λ_(ex)/λ_(em)=225/340)、E(λ_(ex)/λ_(em)=275/325)、F(λ_(ex)/λ_(em)=275/335)与毒性相关性较强,因此,检测发射波长在325~340nm内荧光物质有助于快速表征石化废水活性污泥毒性.

The changes of wastewater toxicity to activated sludge along the treatment processes from water intake to the aerobic biological unit in an integrated petrochemical wastewater treatment plant were investigated. The assay was done based on three toxicity characterization methods： oxygen uptake rate of activated sludge, dehydrogenase activity of activated sludge and acute toxicity to luminescent bacteria. Moreover, the three-dimensional fluorescence spectra of effluents from each process unit were analyzed and the relationship between fluorescence characteristics and the toxicity profiles was revealed. The results showed that the influent petrochemical wastewater had an inhibition on the oxygen uptake rate of nitrifier up to 50%~60%. After the treatment processes prior to the aerobic biological treatment unit, the inhibition of the treated wastewater on activated sludge still reached 30%. Among them, hydrolysis acidification and anoxic treatment were found to decrease the wastewater toxicity obviously. Based on the comprehensive comparison of the results from these three methods, the oxygen uptake rate method is more suitable for the toxicity evaluation of petrochemical wastewater on activated sludge. As to the fluorescence spectra of the water samples, all the fluorescence peaks appeared in the region of λ_（ex）/λ_（em）=200-300/250~400nm, and the fluorescence intensity of peak C（λ_（ex）/λ_（em）=225/340）, peak E（λ_（ex）/λ_（em）=275/325） and peak F（λ_（ex）/λ_（em）=275/335） were positively correlated with the toxicity at a certain extent. The fluorescence peaks with emission wavelength of 325~340nm are recommended to be used for rapid and simple monitoring the toxicity of petrochemical wastewater to activated sludge.