Urine Processing and Water Recovery using Electro Oxidation and Membrane Evaporator

The Electro Oxidation and Membrane Evaporator (EOME) is a partial gravity compatible urine processor to oxidize urine and recover water from urine. The EOME purifies wastewater (augmented urine, flush water, and optional pretreat) by breaking down organic compounds with powerful oxidants such as reactive oxygen species and chlorine containing species. Waste heat generated from the electro-oxidation process facilitates water evaporation through a gas-liquid contactor (GLC), allowing water evaporated from the wastewater to be recovered elsewhere. The resulting brine is offloaded to a brine water recovery system to recover the remaining water. A full scale EOME was designed and 10 L of raw human urine was processed for oxidation. EOME successfully converted the urine into clear acid, dissolved precipitation, and removed total organic carbon (TOC). In order to test worst case for water evaporation, concentrated urine that simulated concentration after ~80% water evaporation was also tested. EOME demonstrated further water evaporation. The results indicate EOME has potential benefits including producing self-generated pretreat and flush water, self-cleaning the wastewater loop, delaying precipitation during water evaporation by oxidizing dissolved solids, and recovering useful gases (e.g., CO2, H2O, N2) from the oxidized components of wastewater which further closes the ECLSS loop. Future work includes increasing water evaporation rate, analysis of gas species leaving the GLC, development of a gas scrubber, and flight concept development.