Space Grant Consortium - University of Wisconsin - Green Bay

Marshall Space Flight Center NASA Academy 2009
ECLSS Vapor Compression Distillation System and Brine Processing
PI: Keith Parrish
RA: Cheryl Perich
ABSTRACT:
In order to conserve liquid hydration resources during extended space missions, Vapor Compression Distillation
(VCD) is used to process condensate, hygiene byproducts, and urine waste. In conjunction with proper pre and
post-treatments used to remove any extraneous organic or volatile matter, the VCD utilizes a simulated gravity
environment in a thermally treated rotating drum in order to remove approximately 85% of water components
from waste solutions, producing drinkable water to a purity of approximately 97% 1 . While this technology has
been customized for use in micro-gravitational fields, such as those experienced on the International Space
Station, the basic water filtration and extraction is to be used in conjunction with a brine processor in attempt to
completely dehydrate waste brine in lunar gravity for future use on the lunar outpost.
ANALYSIS:
I. VCD
The basic principle behind the VCD processor (See Figure 1) involves simple phase changes in order to
separate water from the solution waste. The system boils wastewater to produce and collect the water vapor
before it uses a de-mister and compressor to condense the separated solution. In order to produce maximum
efficiency the pressure inside the VCD is lowered to 0.7 psi to lower the boiling point. To begin, the
wastewater is fed into a rotating drum (220 rpm) to form a thin film coating the walls of the drum. The liquid
then boils off between 90-105 degrees Fahrenheit. The water vapor is then collected by a de-mister in the
center of the drum and fed into a compressor. The collected sample is then injected onto a thin wall around the
outside of the drum where it condenses. The water is then collected for testing, and the remaining brine is
removed for processing and testing. Samples were collected at the beginning and end of the processing cycle
and sent for processing. Tests included: pH/conductivity, TOC, TIC, alcohol, anion/cation, metals, acids, semivolatiles,
volatiles, glycol, non-volatiles, aldehydes, total bacteria, and surface tension.
Figure 1: Vapor Compression Distillation System for ECLSS
Water Recycling.
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