Application of green filters as nature based solutions for wastewater reuse in arid regions

The reuse of treated wastewater represents a sustainable alternative to reduce the overexploitation of water sources, reclaim arid lands, and promote a circular economy. This study examines the communities of Montañita and Libertador Bolívar on the coast of Ecuador to design a community-scale tertiary treatment system based on green filters, using sustainability criteria for the recovery and reuse of treated wastewater in semi-arid environments. The study involved three phases: (i) socio-environmental and hydrological baseline, (ii) design of a green filter system as a tertiary treatment system, and (iii) Environmental Impact Assessment (EIA) for sustainability proposals. Over a 15-year period, the proposed designs will allow the reuse of 1258 m 3 /day of treated sewage and the reforestation of 9.59 ha of arid land for both communities. Based on results from pilot projects, the design considered using guadua bamboo for its high carbon sequestration potential and value as a raw material for crafting and construction. The EIA indicates that the impacts associated with the construction and operation of green filters are of a medium to low degree; however, continuous monitoring and community engagement are essential to ensure the sustainable operation of these treatment systems. The proposed system will facilitate the establishment of a circular economy model for water sustainability and ecosystem restoration.