Natural systems treating greywater and blackwater on-site: Integrating treatment, reuse and landscaping

With increasing water scarcity, reuse of water is becoming increasingly more attractive. Moreover, in large parts of the world centralized sewerage is still not available. In this paper we discuss a solution for treatment and reuse of source segregated domestic wastewater. The blackwater fraction is treated in an evapotranspiration tank (TEvap) system, whereas the greywater fraction is treated by a compact setup including a grease trap, sedimentation tank and two constructed wetlands. Results of both systems, obtained during a 400-days trial in a 9-person household in Campo Grande-MS, Brazil, are presented. Results show that it is possible to introduce an ecological and low-cost alternative to conventional septic tank solutions, to manage both greywater and blackwater at household level, enabling the development of green areas, improving microclimate and allowing for the reuse of grey water and the nutrients present in black water. The TEvap system was essentially maintenance free, but the constructed wetlands did require attention, to prevent clogging of subsystems.

► We show a novel alternative system for small-scale, on-site treatment of grey- and blackwater.
► In the described TEvap system organic material is removed by anaerobic and aerobic digestion.
► Minerals (nutrients) are removed by absorption and by assimilation by plants.
► Under normal conditions all water is lost due to evaporation, so generally there is no effluent.
► Satisfactory tests have been performed for a period of over 400 days.