[Wastewater Quantity and Quality Fluctuation Characteristics of Typical Area of Hybrid Sewage System]

The inflow and infiltration problems cause large fluctuation in wastewater quantity and quality in hybrid sewage system. This seriously challenges the operation and management of sewage system. A multi-point on-line simultaneous monitoring system was established in a typical hybrid sewage system. The key characteristic parameters and their variation features under different circumstances were studied. The result indicated that the daily variation rule was obvious and appeared synchronous among multiple points at normal water level under dry weather flow, but there was no synchronization in conductivity variation among multiple points at high water level under dry weather flow. The statistical distribution range of water level and conductivity was significantly impacted by the seasonal rainfall change under dry weather. The statistical distribution ranges of water level variation rate and conductivity variation rate in specific time were significantly impacted by the rainfall. The response features of water level and conductivity to rainfall intensity and pattern were significantly different under different circumstances. The response sensitivity of conductivity was higher than water level at normal water level and lower at high water level. The database which could support the optimization of operation and management in the hybrid sewage system was proposed based on the distribution law of wastewater quality and quantity fluctuation under dry and wet weather, as well as the variation rate features of wastewater quality and quantity during rainfall obtained using the multi-point on-line simultaneous monitoring system.