For long term manned space missions, considerable quantities of materials for life support will be consumed. The ability to recycle such materials, particularly water, offers significant benefits in reducing the costs and logistical difficulties of resupply from earth. The application of supercritical water oxidation (SCWO) waste treatment and water recycling technology to the problem of waste disposal in space is being developed for NASA by MODAR, Inc. As inorganic constituents present in the waste are not soluble in supercritical water, they must be removed from the organic-free, supercritical fluid reactor effluent. Experimental results are presented on the separation of solids from the process stream by removal mechanisms which could be suitable for a microgravity environment. The solid properties and their influence on the design of several oxidation reactor/solids separator configurations under study are presented.