AWWA QTC98379

This paper describes process optimization of granular activated carbon (GAC) at the Richard Miller Treatment Plant (RMTP), which involved three goals: to provide a more consistent trihalomethane (THM) formation in the distribution system, lowering the warm water values; to continue to provide an effluent water quality below the proposed Stage 2 Disinfectants/Disinfection Byproducts (D/DBP) Rule level of 40 ug/L for THMs; and, to reduce the overall cost of GAC reactivation. To accomplish the first goal, the conditions required to maintain a THM value of <40 ug/L had to be established. THM formation was modeled as a function of total organic carbon (TOC) concentration and water temperature. Chlorine residuals and pH were considered insignificant factors to THM formation because of their consistency leaving the treatment plant. The next step towards optimizing the GAC process was to decide which factors were important to the operation of the reactivation furnaces, and which months of the year would provide the most efficient and cost effective use of the furnaces. Since a change in THM formation was the ultimate goal, seasonal water temperature and TOC would be the most important factors. Operating costs associated with reactivation, such as the cost of natural gas, would also be an important factor. The final step was to set a schedule for the two reactivation furnaces which would take into consideration the potential water quality and reactivation costs. Each furnace was given a 6-month downtime as a maintenance convenience, which would allow the furnaces to be maintained as time permitted. Based on past data, it was also decided to reactivate each of the twelve GAC contactors twice a year. One last consideration was to put sufficient GAC contactors into service as the demand for water required it. Therefore, only eight contactors would be in service during the winter months and as many as eleven during the summer months.

Product Details

Published:

01/01/1998

ISBN(s):

0898679796

Number of Pages:

13

File Size:

1 file , 130 KB