Comprehensive Cost Analysis of Full-Scale Water Treatment Plants Treating Surface Waters

An economic evaluation of water treatment plants (WTPs) is a key factor for the assessment of their economic and environmental sustainability during the decision-making process for the authorities. In this study, the capital and operation and maintenance (O&M) costs were evaluated by analyzing the capital and operational expenditures of 12 full-scale WTPs in Istanbul. Besides, the impacts of treatment capacity and the presence of ozonation unit on costs were investigated. The unit capital costs were found to be 22±3, 15±1, and 12±3 $/1,000 m3 for small, medium, and large capacity WTPs, respectively, while the unit O&M costs were calculated as 36±15, 19±3, and 18±2 $/1,000 m3 for small, medium, and large capacity WTPs, respectively. In addition, it was found that poor raw water quality is associated with high chemical consumption, which was resulted in high O&M cost in WTPs. Small capacity WTPs had a lower share of the chemical cost with a value of 26% than medium and large capacity WTPs, representing 36% and 37% for medium and large capacity WTPs, respectively. Besides, the average unit total cost for small capacity WTPs was found to be 58±13 $/1,000 m3, while it was found to be 34±2 and 30±5 $/1,000 m3 for the medium and large capacity WTPs, respectively. The results obtained from this study are of utmost importance to be used in the economic evaluation of the planned WTPs along with the management of existing ones.