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In order to meet NASA potable water standards using biological processing, additional purification is needed. Elimination of ammonia species is a significant post-treatment step to achieve this goal. New technology, combining membrane transport and electro-oxidation of ammonia, was developed to solve this problem without the use of expendables. The Aqueous Phase Ammonia Removal and Destruction System (APARDS) Phase I Program rigorously demonstrated the feasibility of each sub-process, and an integrated system was developed that removed and destroyed ammonia from a simulated bioreactor effluent. Membranes and process conditions suitable for ammonia removal have been determined. An Ammonia Removal Module (ARM) was designed for the efficient transfer of ammonia to a secondary electro-oxidation stream where the ammonia was destroyed. The electrolysis cell's electrodes, operational voltage, and flow characteristics were optimized to rapidly destroy ammonia.

The initial development effort is described for an electrochemical hydrogen peroxide generator and pervaporation module capable of producing and delivering hydrogen peroxide to a contaminated waste water stream as an oxidant or to a pure water stream for use as a disinfectant. A three chambered cell is used to generate hydrogen peroxide by a combined electrodialysis and electrochemical process. Each chamber is separated from its neighbor by a membrane allowing selective production of peroxide anions and hydrogen ions under controlled pH conditions followed by migration to form hydrogen peroxide. Concentrations greater than 6,500mg/L have been produced in this manner. The effects of voltage, pH, membranes, electrode materials, and method of oxygen introduction are delineated. Hydrogen peroxide is then transferred to the end-use stream by pervaporation. The impact of pH, relative flow rates, and ionic strength of sink and source solutions on pervaporation rates is detailed.

A computer interfaced instrument designed to quantify ammonia and other nitrogenous species that are important regenerative life support water quality parameters is described in this paper. Measurements can be made either discretely by Flow Injection Analysis (FIA) or continuously using a split stream from a process flow. The monitor exhibits a predictable quadratic response for ammonia injections between 10 μg/L to 20 mg/L with a response time less than six minutes. A full description of the ammonia monitor's response to a variety of challenge solutions including real sewage treatment plant effluent is given. In addition, the response time characteristics, the effects of temperature, and interferences are described.

A breadboard Electrochemical Water Recovery System (EWRS) that is designed to produce potable water from a composite waste stream without the use of expendables is described in this paper. Umpqua Research Company working together with NASA/JSC developed a sequential three-step process to accomplish this task. Electrolysis removes approximately 60% of the organic contaminants from ersatz composite waste water containing a total organic carbon (TOC) concentration of 707 mg/L. The contaminants in this solution consist of organic and inorganic impurities common to laundry, shower, handwash, and urine waste water. Useful gases and organic acids are the chief by-products of the first step. The partially oxidized electrolysis solution is then transferred to the electrodialysis process where ionized organic and inorganic species are concentrated into a brine. The deionized solution of recovered water contains ∼6% of the original organic contaminants and >90% of the original water.