Coliphages as a rapid indicator of sequencing batch reactor (SBR) treatment performance

Generally, conventional tests for total and fecal coliforms take from 1 to 4 days before the results are available. In contrast, the coliphage method is a simple, rapid, economical, and reliable method that has been used as an additional indicator of potential pathogens whereby coliform numbers present in natural waters can be estimated within 6-24 h. In this pilot-scale study, besides demonstrating that the 6-h coliphage test may be used to evaluate sequencing batch reactor (SBR) treatment efficiency (up to 99% removal), predictions of coliform numbers were made by enumeration of the coliphages. Coliform-coliphage correlationships similar to that for natural water (as proposed by the American Public Health Association's Standard Methods, 1989) and SBR treated domestic sewage have been developed for SBR treated combined sewage: log TC = 0.798(log P) + 3.921 where TC is total coliforms/100 mL and P is the coliphages/100 mL, and log FC = 0.850(log P) + 3.501 where FC is fecal coliforms/100 mL and P is coliphages/100 mL. Comparison between the logarithm of coliphages after 24 h incubation with the logarithm of coliphages after 6 h incubation yielded correlation coefficients of at least 0.91 suggesting that the 6 h coliphage detection test is sufficient for use as a rapid test and may be correlated to coliform numbers in sewage.