Case Study on the Long-Term Performance and Economic Evaluation of the NEWater Program in Singapore

The Changi NEWater Project Phase 2 purifies the secondary effluent of an urban sewage treatment plant using a two-stage microfiltration membrane (MF) and reverse osmosis (RO) process to produce NEWater for industrial use and to supplement drinking water sources. The total recovery rate of the system was 73.5%. The turbidity removal rate of the MF unit was 93.4% and the silt density index (SDI) value of MF product water was stable below 3. The performance of the pretreatment unit met the design standards. After reverse osmosis treatment, the total organic carbon removal rate was 99.4% and the desalination rate was greater than 99%. The quality of the NEWater was superior to the drinking-water standards of Singapore and the World Health Organization. Because of its advanced automatic control system, the Changi NEWater Project Phase 2 required a staff of only 15 operation and management personnel. The total operational cost was between 0.08 and 0.15 $/m³, of which energy consumption, chemical consumption, maintenance costs, and labor costs accounted for 62.9%, 20.2%, 7.3% and 9.6%, respectively. The energy consumption was between 0.6 and 0.8 kWh/m³. The Changi NEWater Project Phase 2 represents a milestone in water cycle engineering practice because of its excellent process design, superior product water quality, high degree of automatic control, and low operational energy consumption.