The freezing and gas hydrate processes for demineralizing sea water are adapted in a preliminary design to renovate municipal waste waters. Assuming a feed material containing 1,000 parts total dissolved solids per million, the author predicts costs for recovering 92 percent of the feed as potable water (250 ppm TDS). The waste stream can be further concentrated under eutectic conditions to produce more water and a waste stream of damp solids. Cost of disposal of the concentrated waste stream is not included in either case. In 14 actual freezing tests completed, chemical oxygen demand (COD) was reduced 65 to 85 percent; chlorides 85 to 90 percent; and conductivity, 90 percent or more. Reduction of alkylbenzene sulfonate (ABS) was erratic. The isobutane used as a refrigerant interfered in the COD tests. With data from the better test runs, preliminary cost estimates indicate that 95 percent of the feed water containing 10 percent of the contaminants can be recovered at a cost somewhat lower than that predicted for desalinating sea water by freezing. (Author)