Costeffective Locating Inappropriate Rainfall Inflow into Urban Sewer Network

Abstract:

Inappropriate rainfall connection to the sewer network would not only degrade the treatment efficiency of wastewater treatment plant, but also lead to sewer’s wastewater overflow on wetweather days. The identification of sewer’s rainfall inflow by simultaneous flow measurements in manholes being hard to implement, a costeffective approach based on marker species monitoring of the sewer network was presented. Specifically, total nitrogen and electrical conductivity being employed as the markers of sewage and rainfall respectively, in combination with the geographic information system of pollution sources, chemical mass balance at the sewer network nodes and data library of marker inflow concentration, the dryweather flow as well as the rainfall inflow received by each sewer segment could be quantified effectively. A case study to identify inappropriate rainfall inflow into the sewer network of Chaohu City, Anhui Province, of China, showed the reliability of the proposed approach, hence the basic principles for the method application was recommended.

Key words:sewage network; rainfall connecting to sewers; drainage system inspection; marker species