Modelling chlorine decay in a pilot scale water distribution system subjected to transient

The reduction of residual chlorine concentration in water distribution systems depends on hydraulic conditions. Prediction models for chlorine decay in water distribution system were based on an assumption of steady flow. In actual systems, the flow condition is frequently governed by transients generated through valve control or pumping action. The chlorine concentration can be affected by pressure variations from water hammer events, but there have been few studies on the impact of transient on chlorine concentration. A pilot-scale pipeline system and automatic transient generating device was fabricated. Transients were introduced into the pipeline system in three different frequencies. Time series of the chlorine concentration were obtained through experimental periods. Conventional chlorine decay kinetic models were tested to model the temporal variation in chlorine concentration. The chlorine decay patterns were modelled in the context of the number of transient generation.