Simulation and control of chlorine levels in water distribution networks

Chlorine concentration is an important parameter used to assess the quality of water supplied by a distribution network. While several water quality simulators are readily available (e.g., EPANET software), water quality optimization decision support tools are currently lacking. A new control-oriented calculation model for chlorine concentrations in distribution networks is presented for general water distribution networks operating under periodic demand conditions. The model is based upon the analysis of the characteristic curves of the concentration transport-reaction equation over each pipe in a network. Numerical results are comparable with EPANET results, but unlike other water quality algorithms, the current method requires neither discretizations along the pipes, nor the choice of initial conditions. Moreover, it is a first step toward a method for controlling concentrations, yielding linear relationships between the concentrations at both ends of each pipe by the explicit inclusion of system dynamics. These relationships can be used as constraints in a linear programming optimization model that minimizes deviations from permissible concentration levels.