Chlorine as an integrated approach for environmental health and hygiene: A case study on evaluation of the performance of waste stabilization ponds located at 11 governorates in Egypt

Abstract

The current study summarizes the current status of wastewater stabilization ponds (WSPs) treatment plants that have already been built in 11 governorates throughout Egypt. Moreover, this study aims to determine the most appropriate chlorine dose for waste stabilization ponds (WSPs) effluents to ensure the treated effluents are suitable for reuse in unrestricted irrigation and to comply with the current legislation on direct discharge onto water bodies. According to the findings, the chlorine doses used as a disinfectant in the treated effluents of the majority of WSP treatment plants ranged from 3 to 13 mg/L. Meanwhile, two of the WSPs treatment plants effluents, the Qus WSPs treatment plant in Qena governorate and the Al Zarabii WSPs treatment plant in Asyut governorate used high chlorine doses reached to 17 and 19 mg/L, respectively. This is due to the fact that both the Qus and Al Zarabii WSPs treatment plants have a high organic load, which necessitated the use of more chlorine to achieve the optimum chlorine dose at 13 mg/L for Qus and 11mg/L for Al Zarabii. The findings demonstrated that chlorine has a powerful effect in completely removing bacteria. Furthermore, in most chlorine-treated wastewater final effluents, as the chlorine doses increased, the chlorophyll-a reading decreased. The amount of trihalomethanes (THMs) produced as disinfectant byproduct was measured. The results proved that the water can be used in unrestricted irrigation, and after adding chlorine, it can be dumped on water bodies without health risks.

Keywords

• Waste stabilization ponds
• Microbial pathogens
• Chlorine doses
• Trihalomethanes (THMs)