AWWA WQTC55033

The City of Houston, Texas has been aware of the implications that current and pending regulatory standards would have on the operation of their four surface water treatment facilities. In particular, the City has closely monitored changes in regulations related to enhanced coagulation, total organic carbon (TOC) removal, and disinfection byproducts (DBP) reduction. The City has, and continues, to conduct extensive bench, pilot, and plant scale tests to determine how these regulatory changes would impact the operation of their surface water facilities. In a collaborative effort between the Water Quality Laboratory and the Operations Group at the City's East Water Purification Complex (EWPC), an evaluation of on-line TOC equipment has been completed. After nearly a year of plant scale evaluation, the recommendation is being made that on-line TOC analyzers be purchased to enhance facility operations. During the trial, the instrument was used to monitor plant performance and to evaluate alternate coagulants and coagulant aids. The most interesting results of the study related to how poorly the operators responded to changing raw water parameters when given daily grab sample results and how much better they were able to respond when allowed to utilize the on-line analyzer. The on-line TOC analyzer allowed the operators to track real time water quality changes and therefore respond much quicker than would be possible if grab samples were being used. Because the City of Houston has two raw water sources that are dramatically different (alkalinity, pH, turbidity, TOC concentration, and TOC composition), blends of the two raw water sources present special treatment challenges, especially related to coagulation efficiency and TOC removal. This paper will discuss the results of a variety of tests and it will examine the advantages and disadvantages of implementing continuous on-line TOC monitoring. When considering the economic implication of applying enhanced coagulation measures, it becomes clear that the closer the operator is able to maintain the required TOC removal percentage without overfeeding, the lower the operation cost to the utility. Operating without the proper instrumentation costs money and results in a lower quality water for the utility customers. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

01/01/2001

Number of Pages:

14

File Size:

1 file , 330 KB