Experimental study on pollution release and sediment scour of sewage sediments in drainage pipe considering incubation time

Abstract The pollution release and the anti-scourability characteristics of the pipe sewage sediments can directly determine the blockage status of pipeline and treatment burden at the terminal (sewage treatment plant). In this study, the sewer environment under different buried depths was designed to explore the impact of incubation time on the physicochemical characteristics, pollution release effect and anti-scouring ability of the silted sediment in the drainage pipe. The results show that, incubation time, sediment matrix, temperature and dissolved oxygen can affect microbial activity, but temperature has a greater influence. These factors affect microbial activity and loosen the superstructure in the sediment. In addition, by measuring the indexes of nitrogen and phosphorus in the overlying water, it was found that the sediment incubated for a certain time can release pollutants to 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 appear on the sediment surface, and the anti-scourability of sediment was significantly improved, which was reflected in the increase of the median particle size of sediment left in the pipe.