Feasibility of vertical ecosystem for sustainable water treatment and reuse in touristic resorts.

To counteract increasing water scarcity in the Mediterranean region, this study provides data on the efficiency of a decentralized, nature-based solution for hotel greywater (GW) treatment and reuse. A pilot plant of a constructed wetland called Vertical Ecosystem (vertECO), installed in a large hotel with GW separation, was operated continuously for 12 months. vertECO achieved a removal efficiency higher than 84.0% for COD and TSS and higher than 95.4% for turbidity and BOD. The monitored physicochemical parameters in the effluent meet the requirements for many reuse purposes restricted in the water reuse legislation. Based on the pilot operation, an economic model was set to estimate its economic feasibility (CAPEX, OPEX and payback period of investment) at several treated volumes. The payback was calculated, at the water and energy prices of Spain and other countries, with a planned operation period of 20 years. The higher the water price, the lower was the payback period. Treated GW volumes of 10.5 and 20 m/day correspond to payback periods for Spain of 10.1 years and 9.0 years, respectively. Finally, co-benefits of vertECO have been considered alongside economic terms, and compared with another intensive technology (i.e., membrane bioreactor).