“Computational Civil Engineering - "Intersections" International Journal

“Computational Civil Engineering 2005”, International Symposium 2731. INTRODUCTIONBooster disinfection is the addition of disinfectant at locations distributedthroughout a water distribution system with the goal to assure the transported waterbiostability, with a minimum chlorine consumption.Chlorine introduction in distribution network may be realized by:1. chlorine injection only in water supply nodes;2. chlorine injection in more network nodes ( inclusively in the supply ones)The last procedure assures a more uniform distribution of chlorine concentrationand permits chlorine consumption optimization by convenient choosing of boosterinjection locations, with a optimization model. Optimization models is formulatedfor a dynamic schedule of disinfectant injections and to minimize the total doserequired for necessary chlorine assurance in limits required by Law 458/2002 andthe avoidance of disinfection by-products formation ( e.g.. trihalomethanes).Even though the optimization problem is of unfinite-time horizon type, it isreduced to a finite-time problem by considering of periodicity for chlorineinjections and network hydraulics (on a extended period to 24 hours).The model is linear because it is shown that the disinfectant concentrations atcontrol nodes come/result from more injection points may be applied them thelinear superposition principleSpecialized literature presents the following possibilities (models) for theestablishing of optimal (minimum) consuming chlorine dose and the locations ofbooster stations1. Optimal scheduling of doses at booster stations as a linear programming problem(simplex method). It is established the minimum chlorine dose considering thatthey are known the locations of booster stations.2. Optimal location and scheduling of booster-station dosing as a mixed-integerlinear programming problem. It is applied the branch-and-bound techniquecombined with the simplex method.3. Optimal location of booster stations as a maximum set-covering problem4. Optimal location of booster stations with a genetic algorithm. It is establishedthe location of booster stations and minimum chlorine doseWith a personal program, by the simulation, they are established the nodes thatassure the minimization of total chlorine injection in the distribution network, froma set of nodes random proposed or imposed by a number of simulations that assurethe chlorine consumption in required minimum and maximum limits