Removal efficiencies of indicator micro-organisms in sewage treatment plants

T. Omura, M. Onuma, J. Aizawa, T. Umita, T. Yagi

Research output: Contribution to journalConference articlepeer-review

20 Citations (Scopus)


The removal of coliform bacteria, enterococcus bacteria, and coliphages in two sewage treatment plants, one using the activated sludge process and the other using a high-rate trickling filter, was investigated over a period of one year. Coliform and enterococcus bacteria were removed with equal efficiency by the two plants, but coliphages were removed more efficiently by the activated sludge process. Experiments on the mechanism of removal revealed that it was mainly due to adsorption on the activated sludge and on the slime in the trickling filter. Die-off of the micro-organisms seemed to play a minor role in the reduction in counts. The treated sewage was disinfected by chlorination prior to discharge into the receiving water. No coliforms were detected in the chlorinated effluents when they had chlorine residuals in the range of 0 to 1.521 mg/l. However, enterococci were detected when chlorine residuals dropped below 0.598 mg/l. Coliphages proved to be the most resistant organisms and they were generally detected throughout the range of chlorine residuals encountered.

Original languageEnglish
Pages (from-to)119-124
Number of pages6
JournalWater Science and Technology
Issue number3
Publication statusPublished - 1989 Jan 1
EventHealth-Related Water Microbiology 1988 - Brighton, Engl
Duration: 1988 Jul 191988 Jul 21

ASJC Scopus subject areas

  • Environmental Engineering
  • Water Science and Technology


Dive into the research topics of 'Removal efficiencies of indicator micro-organisms in sewage treatment plants'. Together they form a unique fingerprint.

Cite this