Decentralized grey and black water reuse by combining a vertical flow constructed wetland and membrane based potable water system: Full scale demonstration

Safe drinking water is not accessible in many rural and peri-urban areas. Decentralized wastewater treatment can be a sensible solution for communities of any size and/or demographic having a very small water cycle and could be used as a solution to provide potable water at more remote locations. In view of demonstrating decentralized production of potable water, a hybrid system combining a vertical flow constructed wetland (VFCW) and a membrane filtration system was designed and operated at a restaurant. The VFCW with an area of 60 m(2) was constructed and operated for six months at a hydraulic loading rate of 0.05 to 0.08 m(3).m(-2).d(-1) and achieved a removal of 84%, 97%, 92%, 42% and 24% for chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended solids (TSS), total nitrogen (TN) and total phosphorus (TP) respectively, corresponding to mass loading rates of 9.6 gCOD.m(-2).d(-1), 7.9 gBOD.m(-2).d(-1), 4.7 gTSS. m(-2).d(-1), 1.5 gTN.m(-2).d(-1). Final (average) effluent concentrations were 7 mg.L-1, 1.6 mg.L-1, 4.7 mg.L-1, 1.5 mg N.L 1 and 1.5 mg P.L-1 for respectively COD, BOD5, TSS, TN and TP. The VFCW effluent was further treated using a combination of activated carbon, ultrafiltration, reverse osmosis and mixed bed ion exchange, remineralization as well as ultraviolet disinfection to produce potable water. This potable water met the legislative criteria and was used in the restaurant for drinking and cleaning purposes. As such, a sustainable decentralized potable water system with direct black water reuse was demonstrated at full-scale