Quality and Cost Evaluation of Treatment Processes for a Specific Water

Abstract

This article discusses a study by the East Bay Municipal Utility District to determine whether any of several other methods of treatment would provide qualitative or economic advantages over the rapid sand filtration process that has been used with the same raw water for the past 28 years. Treatment methods considered for the new Walnut Creek treatment plant were: rapid sand filtration; anthracite, sand and anthracite, and diatomaceous‐earth filtration; microstrainers; and, high‐ and conventional‐rate sedimentation. The use of these methods was studied both as single‐stage processes and as one stage of two‐stage processes. The present‐worth method was selected for making the economic evaluation, as this seemed the most convenient method of accounting for the four types of costs that include constant costs, such as those for construction.