An Innovative Triple Water Supply System and a Novel SANI® Process to Alleviate Water Shortage and Pollution Problem for Water-scarce Coastal Areas in China

G. H. Chen, H. K. Chui, C. L. Wong, Daniel T. W. Tang, H. Lu, F. Jiang, M. C. M. van Loosdrecht



Water scarcity has been a long standing problem in China, especially in North China. To tackle water scarcity, we have developed a low-cost Triple Water Supply (TWS) system consisting of fresh water supply, seawater for toilet flushing, and grey water reuse and recycling. This innovative system maximizes the water resource saving in coastal cities up to 23%. Moreover, this novel system opens the door for adopting an innovative sewage treatment technology, namely the SANI® process which effectively avoids sewage sludge production. If the TWS system and the SANI® system were to be jointly applied to the 16 major water-stressed coastal cities of China, this could possibly reduce 3,600 million m3/year of freshwater demand. As compared with wastewater reuse and desalination, the reduction of annual electricity and greenhouse gas emission by seawater toilet flushing can amount to 630 – 22,000 GWh and 0.4 – 15 million tonnes of CO2, respectively. Moreover, the SANI process can avoid the production of 10 million tonnes of sludge, reducing 35% energy consumption and 36% greenhouse gas emission as compared to conventional sewage treatment processes. This is equals to 1,400 GWh/year energy saving and 1.2 million tonnes of CO2/year emission reduction, respectively.


Keywords: Seawater toilet flushing; Water reuse; Sewage treatment; SANI process