Control of DBPs in water distribution systems through optimal chlorine dosage and disinfection station allocation

Two different procedures, respectively aiming at the best allocation and managing of disinfection stations along water distribution systems, are presented, with the main objective of proposing a criterion to limit chlorine and disinfection by-product concentrations in the drinking water supplied to users without compromising its agreeableness and safety characteristics. The procedures are based on the evaluation of two different indexes obtained through the analysis of several operating conditions related to changes of water demands in both space and time and to the random behaviour of users: the Presence Index and the Efficiency of Allocation Index. The proposed procedures have been applied to a case study in order to determine, respectively, (1) the number and the allocation of chlorine booster stations according to minimum and maximum values of chlorine concentration indicated in drinking water standards and to minimum chlorine dosage allowed for each station; and (2) the optimal dosage of chlorine according to the number and allocation of chlorine disinfection stations and to the changes of water demand from users.

The necessities associated with the protection of water quality characteristics in a water distribution network and to the risks of eventual contamination demonstrate the exigency of installing a few chlorine stations along the system and to manage them correctly. However, to contemporarily satisfy the agreeableness and biological and toxicological safety of the water, limiting chlorine and DBP concentration, a very important issue is the application of effective methodologies for the best allocation of chlorine stations along the network, able to consider the variations in the water demand from users. In the present paper, an innovative, probability-based procedure for the optimal allocation of chlorine stations along the network was proposed, together with another procedure to optimise the chlorine dosage considering the hourly and partially random variations of water demand. The obtained results were totally acceptable from technical and conceptual points of view and open a door for future and rapid development of the present research towards the safety of citizens, and in consideration of the possibility of terrorist attacks in a water distribution network.