Urban wastewater reuse using a coupling between nanofiltration and ozonation: Techno-economic assessment

Abstract

Combination of nanofiltration and ozonation was investigated for the treatment of urban wastewater. First objective was to demonstrate that nanofiltration can be used instead of reverse osmosis as it enables good rejection rates with reduced cost because of lower operating and maintenance costs. In this way, this paper presents an economic and technical evaluation of the proposed coupling where ozonation is used to treat retentates from nanofiltration. Reverse Osmosis System Analysis (ROSA) software was applied to simulate the filtration design. The effect of membrane choice on specific energy consumption, capital, operation and maintenance costs and scaling potential was investigated. It was demonstrated that using nanofiltration instead of reverse osmosis enable cost saving of 35 k$/year for 125 m3/h. Second objective was to evaluate the impact of the treatment of retentates by ozonation on the global cost. It was highlighted that the coupling would be an acceptable solution from an economic point of view for wastewater reuse. The possible reuse of both permeate and concentrate enable an operating cost saving of 15.4 k$/year for 125 m3/h. An optimum recovery rate of 80% was found for which cost of membrane process is balanced by a decrease in the cost of ozonation.