流态变化对污水管网沉积污染物分布及转化的影响

为探明城市污水汇流管网流速变化对沉积层污染物及生物菌群演替的影响，通过控制污水管道中试系统中干管、支管流速，模拟了不同汇流条件下城市污水管网系统运行状态，探究了不同汇流条件下沉积层碳、氮、硫类污染物的分布特征以及微生物种群结构的分布规律.结果表明，在不同汇流条件下，COD、TN、NH₃-N、NO₃-N、硫酸盐含量沿沉积层深度方向均逐渐减小，而硫化物含量逐渐升高.当干管、支管流速均增加时，促进了汇流区域不同深度污染物的沉积富集，但由于DO、ORP环境因子的改变，以及流速的增大，将沉积层中原有的碳源基质剥离到污水中，减少了微生物可利用的营养物质，同时造成沉积层内部溶解氧含量的上升，沉积层中产甲烷菌（MA）中优势菌属Methanosaeta、硫酸盐还原菌（SRB）中优势菌属Desulfomicrobium、水解发酵菌（FB）中优势菌属Caldisericum的相对丰度逐渐降低，硫氧化细菌（SOB）中优势菌属Thiobacillus相对丰度增加，显著影响了沉积污染物的转化特性.污水管网汇流区域流态是改变污水水质及管道微生物系统的重要因素.

Influence of flow regime changes on the distribution and transformation of sediment pollutants in sewer system

To prove the convergence of urban sewage pipe network flow velocity change on sediment pollutant and the influence of the biological flora succession, by controlling the sewer pilot system, main and branch pipe flow under different flow conditions to simulate the urban sewage pipe network system running condition, explored the sediment under different flow conditions of carbon, nitrogen and sulfur pollutants distribution characteristics and the distribution of microbial population structure. The results showed that under different confluence conditions, the contents of COD, TN, NH₃^--N, NO₃^--N and sulfate gradually decreased along the direction of sedimentary depth, while the content of sulfide gradually increased. When the main and branch pipe velocity all increased, promoted the convergence of the deposition of pollutants accumulation areas of different depth, but because of the change in the DO and ORP environment factor and the increase of flow velocity, the sediment in carbon source in the lithosphere matrix into sewage, reduced microbial available nutrients, at the same time caused the rise of dissolved oxygen content in the sediment. The relative abundance of Methanosaeta in methanogen (MA), Desulfomicrobium in SRB and Caldisericum in hydrolytic fermentation (FB) in the sedimentary layer gradually decreased. The relative abundance of Thiobacillus, the dominant bacteria in sulfur oxidizing bacteria (SOB) increased, which significantly affected the transformation characteristics of the deposited pollutants. The flow pattern in the confluence area of the sewage network was an important factor to change the sewage quality and the microbial system of the pipeline.