Optimization Of Booster Disinfection Scheme In Water Distribution Systems And Its Application

Booster disinfection, by injecting disinfectant at some intermediate locations, couldimprove the disinfection effect of the whole network, and reduce the production ofdisinfection by-products (DBPs). The research on booster disinfection has been basedon “blank networks”, which neglects the existing disinfection facilities in the network,thus could not provide optimal booster disinfection plan to improve the existingdisinfection situation.The proposed research has been carried out on a network in CP town in northChina. The optimal disinfectant is optimized by the Fuzzy Analytic Hierarchy Process.The booster disinfection plan, including the locations and respective injection rates, areoptimized in the model which employs the Particle Backtracking Algorithm and thelinear superposition theory. There are some major results listed below:(1) The Fuzzy Analytic Hierarchy Process, which incorporates the properties of thedisinfectants in the selection model, could provide decision-making support in theselection of disinfectants for small towns. The optimized disinfectant in CP town ischlorine dioxide.(2) Based on the existing disinfection situation of the network, the ParticleBacktracking Algorithm, which could trace back the upstream nodes of the disinfectantinsufficient nodes, is employed to narrow down the potential locations for boosterdisinfection stations. The size of the “candidate pool” of potential booster stationlocations in CP town is reduced from3339to1559by the Particle BacktrackingAlgorithm.(3) The “coverage matrix” is calculated for location optimization under any boosterstation number. The model has provided8location solutions that could cover maximumnumber of disinfection insufficient cases with booster station number from1to8.(4) The linear superposition theory is employed to calculate the disinfectantconcentration of the nodes. It could help calculate the minimum injection rates at thebooster disinfection stations, saving the time-consuming water quality simulation usingEPANET.(5) The model also optimizes the number of booster disinfection stations. Byanalyzing the coverage, minimum injection rate and coverage overlap number results, the model recommends CP town to establish4booster disinfection stations. The totalcoverage of the solution is73.6%, and the minimum injection rates of the boosterstations are0.5981mg/L，0.3486mg/L，0.2556mg/L and0.59mg/, respectively.