AWWA JAW56654

Nitrification affects many water utilities that use chloramineas the finished water disinfectant, but traditional nitrificationcontrol strategies are not always effective. Althoughthe utility can change from chloramine disinfection to free chlorineto control nitrification, the disinfection byproducts (DBPs) producedby free chlorination are just as problematic as the nitrification.With increased use of chloramination to meet the requirementsof the Disinfectants/DBP Rule, nitrification will become anissue for more utilities.Skadsen reviewed historical water quality data and the occurrenceof nitrification in the Ann Arbor, Mich., water system andsaw a correlation between high pH and low occurrence of nitrification.If this correlation held true during full-scale operation atthe Ann Arbor water plant, raising the pH of finished water mightbe a relatively simple alternative for preventing nitrification.Successful experiments prompted the utility to set an operationalgoal of pH 9.3 for its finished water and to conduct aneight-year assessment to evaluate the effects of the higher pHon the occurrence and degree of nitrification. The elevated pHsignificantly improved the control of nitrification but did notcompletely eliminate it. This experience indicates that raisingfinished water to pH 9.3 is a practical step for controlling nitrification,although additional control methods may be required insome cases. Includes 32 references, tables, figures.

Product Details

Edition:

Vol. 94 - No. 7

Published:

07/01/2002

Number of Pages:

11

File Size:

1 file , 230 KB