The effect of water treatment stages in Al-Wathba water treatment plant in Baghdad city on the bacterial growth (applied study)

Abstract

The aim of this research is to study the biological pollution in Al-Wathba water treatment plant stages (new extension) by taking water samples from the river, sedimentation tank, sand filter, pressure filter, and from three residential areas (Al-Atebaa neighborhood, Al-Amen neighborhood, and Al-Shorja), with the examination of bacterial growth, temperature, pH, and turbidity in each stage. Weekly samples have been taken for the period from January 2011 to May 2011 by studying the bacterial existence using total plate count, and also by testing for total and fecal coliform using presumptive and confirmed test because it is the evidence for bacterial pollution. There was high percentage of pollution in the sedimentation tank and less amount in sand filter due to lack of periodic cleaning. Fecal coliform reduced after pressure filtration; small amounts of chlorine were added to the filter to reduce the bacterial growth in filter media. After chlorination the removal efficiency was 99.99%. It was noticed that the chlorine dose added for disinfection was so high that it reached up to 3.5 mg/L, which is dangerous especially for people near water treatment plants.

Keywords:

• Total plate count
• Fecal coliform
• Chlorination
• Bacterial growth