A significant concern associated with chloramination is nitrification caused by the growth of
ammonia-oxidizing bacteria (AOB) in the distribution system. To prevent nitrification, any
measures designed to slow the decay of chloramine and its associated release of ammonia
should theoretically reduce the occurrence of AOB growth. Pilot-scale studies were used to
evaluate whether enhanced removal of natural organic matter and pH adjustment delayed the
onset of nitrification. For the system described in this article, nitrification occurred at pH
values ranging from 7.9 to 8.9, with the time to onset of nitrification being fastest at about pH
8.5. However, pretreatment with enhanced coagulation successfully delayed the onset of
nitrification compared with pretreatment with conventional coagulation. Nitrification did not
occur when total chlorine concentrations were 2.2 mg/L as Cl2 or more. Similarly, nitrification
did not occur in locations with biocide-to-food ratios of 1.9 mg Cl2/mg N or more. Includes 19 references, tables, figures.
| Edition : | Vol. 94 - No. 11 |
| File Size : | 1
file
, 310 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 12 |
| Published : | 11/01/2002 |
