Physico-Chemical Evaluation of Drinking Water Treatment Plant and Sand Filter Backwashing Water for Possible Recycling: A Case Study

Abstract

A COMPARATIVE chemical study was carried out to evaluate the physical, chemical and biological characteristics of a selected Drinking Water Treatment Plant (DWTP) in Egypt. The evaluation includes the inlet fresh water of the Canal, the produced drinking water (DW) and the sand filter backwashing water (BWW). An extensive sampling program was carried out to collect water from each of these studied points. All experimental studies were carried out according to APHA. The results showed that the Canal water is not contaminated by any hazardous pollutants, and the conventional treatment system of the plant could successfully produce good quality of DW that cope with the Egyptian, WHO and EPA regulations. The characteristics of the BWW showed slight increase of TSS, turbidity and aluminum. This water consists of 19.5% of the produced DW and is daily discharged to the Canal water way. Thus, it is a source of contamination to the Canal. Several recommendations are included in this study to the decision makers that can save 20% of the wasted water in one hand and protect the waterways of the Canal on the other hand. The pre-chlorination of the fresh Canal water in the DWTP should be replaced by ozone instead of chlorine to avoid any formation of trihalomethanes that might be available in the Canal. Meanwhile, the Canal should be prevented from the disposal of the BWW. Thus, the BWW should not be wasted; it should be reused for other purposes such as irrigating the green area around the DWTP, for flushing, or treated by using simple system and recycled. This will prevent the ecosystem of the Canal in one hand and can be as additional water resources on the other hand. The chemical characteristics of the BWW should be carried-out periodically along with the surface and the produced drinking water to ensure the suitability of BWW for recycling.