[Identifying dry-weather flow and pollution load sources of separate storm sewer systems with different degrees of illicit discharge].

Dry-weather flow quantity and quality of three representative separate storm sewer systems in Shanghai-H, G, N were studied. Based on survey of operating status of the pumping stations as well as characteristics of the drainage systems, it was obtained that the interception sewage volumes per unit area in the three systems were 3610 m3/(km2 x d), 1550 m3/(km2 x d), 2970 m3/(km2 x d) respectively; the sanitary wastewater included accounted for 25%, 85% and 71% respectively; the interception volume of H was mainly composed of infiltrated underground water, so the dry-weather flow pollution was slighter, and the interception volumes of G, N were both mainly composed of sanitary wastewater, so the dry-weather which were flow pollution was relatively serious. The water characteristics of potential illicit discharge sources of dry-weather which were flow-grey water, black water and underground water were preliminarily explored, so that treating three parameters-LAS/ NH4+ -N, NH4+ -N/K, Mg/K as tracer parameters of grey water, black water and underground water was put forward. Moreover, the water characteristics of grey water and sanitary wastewater including black water were summarized: the feature of grey water was LAS/NH4+ -N > 0.2, NH4+ -N/K <1, and sanitary wastewater was LAS/NH4+ -N < 0.2, NH4+ -N/K >1. Based on the above, the applications of flow chart method and CMBM method in dry-weather flow detection of monitored storm systems were preliminarily discussed, and the results were basically same as that obtained in flow quantity and quality comprehensive analysis. The research results and methods can provide guidance for analysis and diagnosis of dry-weather flow sources and subsequent reconstruction projects in similar separate storm sewer systems at home.