The use of vapor compression distillation for recycling gray water as an early application in the antarctic planetary analog

Abstract

Gray water is a major fraction of the waste water from small isolated outposts such as Antarctic bases and planned Lunar and Martian bases. Recycling of this water is a key element in a reliable and efficient life support system. This paper describes the design and test of a gray water recycling system based on vapor compression distillation. The Exploration Program group at LMSC funded WRT to test and obtain data on the use of vapor compression distillation for the recovery of distilled water from gray waters. The gray water recycling tests were conducted using waste waters from household clothes and dish washing machines and from a defined gray water simulant, constituted by LMSC, as the feed to the VCD system which includes a 3 gal/hour wiped microfilm evaporator developed by WRT. Samples of the feed, reject, and distilled water, as well as engineering data were taken to evaluate performance. The tests were conducted in the temperature range of 90 to 120 F. The results show that the system produced excellent quality distilled water with recoveries approaching 99% and with overall heat transfer coefficients ranging from 2000 to 5000 Btu/hrft 2F. Further evaluation of the system is continuing, especially in the area of compatible water quality monitoring equipment and the use of low temperature (120 F) waste heat to drive a multieffect distillation system. More tests are in the planning stage.