A wastewater-recycling system contains biological and physicochemical water-treatment units. The system is suitable for use in environments in which clean water supplies are limited. Waste streams containing urine and washwater are purified into potable water with a recovery rate of 99 percent. The system includes a two-stage trickling-filter bioreactor, a reverse-osmosis unit, and a photocatalytic post-treatment subsystem. The first stage of the bioreactor reduces the concentrations of organic (carbon-based) compounds, while the second stage removes nitrogen compounds. The effluent from the reactor is sent to the reverse-osmosis unit, which passes 85 percent of the water and diverts the other 15 percent into a concentrated brine. Water is recovered from the brine by evaporation. Finally, the water is treated by ultraviolet light and titanium oxide for disinfection and for oxidation of any organic residue. The system can treat small amounts of very concentrated wastewater, without use of pretreatment chemicals, at low power consumption.

This work was done by Marybeth Edeen, Charles Verostko, and Mary Cleave of Johnson Space Center and Nigel Packham of Lockheed. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Machinery/Automation category.