The Efficiency of Removal of Total Coliforms, Faecal Coliforms and Coliphages in a Wastewater Treatment Plant in Riyadh

F. A. Fattouh; M. T. Al-Kahtani

The Efficiency of Removal of Total Coliforms, Faecal Coliforms and Coliphages in a Wastewater Treatment Plant in Riyadh

2002

F. A. Fattouh | M. T. Al-Kahtani

Limited water resources in Saudi Arabia necessitate the re-use of treated wastewater for irrigation, industrial and recreational purposes. The large numbers of pathogenic agents present in wastewater requires continuous monitoring of the removal of such agents from water prior to re-use. In a one year study total and faecal coliforms and coliphages were estimated in monthly samples from a wastewater treatment plant in Riyadh to evaluate the removal efficiency of such indicators at various levels of wastewater treatment. The efficiency of removal of total coliform (TC) and faecal coliform (FC) following aeration and sedimentation processes ranged between (18-34%) and (17-38%) respectively and for coliphages was (4-19%). Chlorinated effluent had negligible counts of TC and FC with an efficiency of removal of (99.2-100%) and (99-100%) for TC and FC respectively whereas the efficiency of removal of coliphages ranged between (91-100%). As coliphages have been proposed as possible indicators of enteric viruses our study suggests their use as indicators of faecal pollution with traditional coliform indicators and the implementation of treatment measures more effective in virus removal in re-used wastewater. Electron microscopy of selected phage lysates showed the presence of tailed coliphages belonging to families Myoviridae, Siphoviridae and Podoviridae. Polyvalent coliphages able to infect enteric bacteria other than E. coli were also detected.

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