AWWA ACE92151

One of the major concerns for the City of Phoenix, Arizona, was required water treatment plant modifications to meet a reduced trihalomethane standard. A consultant devised a series of process modifications and/or changes that could be implemented. The required modifications to existing process operations and additional process units depends upon the final standard set by EPA and the philosophy of the city. That is, whether to use a disinfectant other than chlorine or increase the removal of disinfection byproduct precursor material. The City moved ahead with some recommendations such as installing sulfuric acid feed equipment to depress the pH in order to enhance natural organic matter removal and to eliminate the practice of pre- chlorination. The City focused on a matrix of activities to reduce THMs that would then become standard operational practices. These included enhanced precursors removal such as pH adjustment with sulfuric acid to increase the effectiveness of alum coagulation, the use of alternate coagulants, such as ferric chloride and polymer, the use of powdered activated carbon and biologically-active filters. In addition, each treatment plant was reviewed to determine process capabilities and flexibility. CT values were evaluated for each plant to determine the last point in the treatment process where chlorine could be added and still meet the requirements of the SWTR. The maintenance of microbiological quality was of prime importance.

Product Details

Published:

01/01/1992

ISBN(s):

0898676525

Number of Pages:

22

File Size:

1 file , 470 KB