预氯化对原水管道含氮污染物转化及微生物群落结构的影响

利用原水管道模拟装置,研究了前置预氯化工艺对原水输送过程中含氮污染物转化及微生物群落结构的影响。研究结果表明:低浓度的预氯化过程能够有效促进原水管道中硝化反应的进行,而较高浓度氯(>1.5 mg/L)则会使硝化过程受抑制。原水中溶解性有机氮(DON)浓度增加率随着加氯量的增加而升高,且水体中亲水性小分子DON比例也明显增加。投加低浓度氯(0.5~1.0 mg/L)在一定程度上能够提高原水管道内壁生物膜的微生物多样性,而投加高浓度氯(>1.5 mg/L)则会明显降低微生物多样性。预氯化后,部分耐氯菌门(如厚壁菌门)及菌属(如假单胞菌属、食酸菌属、不动杆菌属)占比逐渐上升并趋于稳定,变形菌门及硝化螺旋菌门在加氯后占比逐渐下降。

Effects of Pre-Chlorination on Nitrogen Pollutant Transformation and Microbial Community Structures in Raw Water Distribution Pipelines

The effect of pre-chlorination on nitrogen transformation and microbial community structures in raw water distribution pipelines were introduced by using a raw water pipeline simulation system.The results indicated that low concentration of pre-chlorination can enhance the nitrification in the raw water pipeline,while high concentration of chlorine(1.5 mg/L)inhibited the nitrification process.The increase rate of dissolved organic nitrogen(DON)concentration in raw water increased with the increase of chlorine dosage,and the proportion of small molecule hydrophilic DON in water also increased after pre-chlorination.Low concentration of pre-chlorination(0.5~1.0 mg/L)can increase microbial diversity in biofilm,while high concentrations(>1.5 mg/L)significantly reducing microbial diversity.After pre-chlorination,the proportion of chlorine-resistant bacteria phylum(such as Firmicum)and genus(such as Pseudomonas,Acidophilus and Acinetobacter)increase gradually in a stabilized way,while the proportions of Proteobacteria and Nitrospirae decreasing after pre-chlorination.