Raw water quality assessment for the treatment of drinking water

Abstract

Changes in the quality of raw water can significantly affect the treatments necessary for drinking water. Generally, raw water quality assessments are carried out to classify the pollution level of raw waters and cannot be used directly as a control for drinking water treatments. In order to improve the adaptability of drinking water treatments and to stabilize the overall quality of treated water, a raw water quality assessment technique that is specifically related to drinking water treatments is developed in this study. First, a drinking water treatment-oriented raw water quality assessment standard is proposed, based on historical environmental information and an analysis of operational data from drinking water treatments. A raw water quality assessment model is then set up to assess the raw water quality in real time. Finally, the results from this assessment are used to compute feedforward compensation for real-time control of the chemical dosing process, including both alum and ozone in the drinking water treatment. In this way, drinking water treatment can be adjusted according to the temporal changes in raw water quality, thereby stabilizing the quality of treated waters. Experimental implementation of this technique has been carried out in the chemical dosing process control systems of a drinking water treatment plant in China, and the results obtained demonstrate the effectiveness of the raw water quality assessment method proposed herein. This development will be helpful in satisfying the basic requirement of safe drinking water under a worsening global water environment.