流态变化对污水管网沉积污染物分布及转化的影响

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.