Evaluation of a System for Residential Treatment and Reuse of Wastewater

Approximately one-quarter of housing units in the United States are not connected to centralized, publicly owned wastewater treatment works and instead operate their own cesspools or septic tanks that provide only partial treatment. A study was conducted in which a commercially available, on-site, residential wastewater package unit was tested at its design capacity according to an established protocol to determine if it could produce a high-quality effluent. Additional pilot-scale sand filtration and ultraviolet disinfection units were fabricated and operated to determine the feasibility of producing recycled water suitable for residential reuse and which could meet strict water reuse regulations. The results indicate that the package unit can produce an effluent equivalent to secondary effluent when properly operated and maintained. In addition, using add-on sand filter and ultraviolet light disinfection units, it was possible to produce the highest quality of reclaimed water recognized by Hawaii regulations (oxidized, filtered, disinfected, unrestricted use). It was also possible and may be economically feasible to produce a slightly lower quality reclaimed water (oxidized, disinfected, R-2) suitable for residential subsurface irrigation.