AWWA WQTC58842

AWWA WQTC58842 Choice of Full-Scale Plants Operation Strategy to Limit THM Formation: NOM Removal and Chlorination Optimization
Conference Proceeding by American Water Works Association, 11/02/2003

Baudin, Isabelle; Bonnard, Reynald; Shedden, Ros; Kirk, Mike; Do-Quang, Zdravka

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The objective of this study was to review water treatment plant (WTP) operation practices in order todecrease the level of Trihalomethanes (THMs) at the outlet of the WT plants and in the distribution system.Specific objectives of this project were:to characterize conditions that lead to the formation of THMs after the final chlorinationfor several water treatment (WT) plants in the United Kingdom;to provide recommendation to prevent or limit THMs formation by optimizing the natural organic matter (NOM)removal and chlorination operating conditions.A global approach was implemented to identify the adverse conditions of THM occurrence onseveral industrial production sites in the United Kingdom. Four different industrial case studies were chosen toillustrate different water quality, different treatment train and different strategies to solve theTHM issue. The study was performed during the 2001/2003 period for sites 1 and 2, and in1999/2001 for sites 3 and 4. The study contained the following tasks:plant operation audits on several WTPs treating surface waters through clarification andpolishing treatment for some of them, with capacities ranging from 15 to 200 Ml/day(around 4 to 53 MGD);extensive quality monitoring of raw waters and of finished waters leaving the differentWTPs to identify the THM levels at the outlet of the WT plants and their evolution in thedistribution systems;building of a database containing information related to resources, plant operationpractices and THM occurrences in treated water in different parts of the distributionsystems;implementation of laboratory-studies to generate the missing data from the plants; and,from full-scale data and predicted values for THM formation establishment ofrecommendations to prevent and limit THM formation by optimizing the NOM removaland chlorination operating conditions according raw water quality variations. Includes 21 references, tables, figures.