Experimental study on pollution release and sediment scouring of sewage sediment in a drainage pipe considering incubation time

The pollution release and the antiscourability characteristics of pipe sewage sediments can directly determine the blockage status of pipelines and the treatment burden at the outflow (sewage treatment plant). In this study, sewer environments with different burial depths were designed to explore the impact of incubation time on microbial activity, and the impacts of microbial activity on the physicochemical characteristics, pollution release effect and antiscouring ability of the silted sediment in the drainage pipe were further explored. The results showed that the incubation time, sediment matrix, temperature and dissolved oxygen affected microbial activity, but temperature had a greater influence. These factors affected microbial activity and loosened the superstructure in the sediment. In addition, by measuring the indices of nitrogen and phosphorus in the overlying water, it was found that sediment incubated for a certain time released pollutants into the overlying water, and the release amount was obviously affected by high temperature (e.g. 35 ℃). After a certain time (e.g. 30 days), biofilms appeared on the sediment surface, and the antiscourability of sediment was significantly improved, which was reflected in the increase in the median particle size of sediment left in the pipe.