Simulation model for predicting the concentration of reactant parameters in water distribution systems

Abstract

Water quality although acceptable when it leaves the source or the treatment plant may deteriorate through the distribution network. The concentration of non-conservative, or reactant constituents in the distribution system, such as chlorine, nitrates, THM etc., is affected both by mixing at the nodes of the network and by chemical or biological processes occurring in the stream flow through the pipes. In complex water supply systems which consist of large number of pipes and nodes the quality simulation of non-conservative constituents needs remarkable capacity of internal computer memory and run time, due to large number of nonlinear equations (Shamir & Howard, 1991). The present article applies steady-state approach to modeling the pipes network as reactors network, assuming first and second order reactions, which meet the kinetics of most reactions in the bulk stream of water distribution and supply systems. The model which has been developed in this work enables the simulation of large water systems with many pipes and nodes as simple structure of plug flow and backmixed reactors with a specific residence time distribution. Thus, controlling the transportation of quality parameters or tracking the movement of accidental contamination within the distribution systems becomes to be much more applicable objective.