INT-ETS活性及AUR和SOUR表征污泥活性的比较

为探索快速评价重金属对污泥活性抑制情况的方法,通过投加不同体积的重金属溶液进行活性污泥培养试验,研究Cd2+、Zn2+和Cr6+对活性污泥降解NH₄+-N和COD_Cr的影响,并分别采用INT-ETS(碘硝基四氮唑脱氢酶)活性、AUR(氨摄取速率)和SOUR(比耗氧速率)3个指标分析污泥活性受重金属抑制的情况. 结果表明:重金属对活性污泥去除NH₄+-N的抑制作用比去除有机物的抑制作用更加显著,说明硝化细菌比异养菌对重金属的毒害作用更为敏感,并且NH₄+-N去除率比COD_Cr去除率更能反映出重金属对污泥活性的影响. 通过NH₄+-N去除率的抑制情况对比发现,AUR是最能有效地用于表征重金属对微生物活性毒害作用的指标. 对于Cd2+,INT-ETS活性的EC₅₀最小,为19.164 mg/L,灵敏度最高,是表征Cd2+抑制污泥活性的最佳指标；对于Zn2+和Cr6+,AUR的EC₅₀最小,分别为40.691和27.117 mg/L,灵敏度最高,是表征Zn2+和Cr6+抑制污泥活性的最佳指标. 由3种重金属的EC₅₀可以判断其毒性大小为Cd2+>Cr6+>Zn6+. 

Comparison of INT-ETS, AUR and SOUR for Characterization of Sludge Activity

In order to explore a method for rapidly estimating the inhibitory effect of heavy metals on the activity of sludge, the influence of Cd2+, Zn2+ and Cr6+ on NH₄+-N and COD_Cr removal was investigated via batch tests of injecting different volumes of heavy metal solution. Three indexes including INT-electron transport system activity (INT-ETS), Ammonia Uptake Rate (AUR) and Specific Oxygen Uptake Rate (SOUR) were used to characterize the inhibitory situation of heavy metals on the activity of sludge. The experimental results showed that the inhibitory effect of heavy metals on removing NH₄+-N was more significant than decomposing organics, and nitrifying bacteria were more sensitive than heterotrophic bacteria to the toxicity of heavy metals. This reflects the toxic influence on the activity of sludge. Besides, compared with the inhibition rate of NH₄+-N removal, AUR was the most effective index that was used to characterize the toxicity of heavy metals. For Cd2+, INT-ETS activity was the most sensitive and optimal parameter, since its EC₅₀ value was the minimum:19.164 mg/L. For Zn2+ and Cr6+, AUR activity was the most sensitive optimal parameter, because its EC₅₀ values were the minimum:40.691 and 27.117 mg/L, respectively. And according to EC₅₀ values, heavy metals were ranked in the sequence of decreasing toxicity:Cd2+>Cr6+>Zn6+.