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Two widespread practices in water treatment are, removal of pollutants via adsorption onto activated carbon, and, oxidation of pollutants using a photocatalyst slurry and ultraviolet radiation. The ultimate goal of this research is to combine the adsorptive properties of carbon and the oxidative properties of titanium dioxide (TiO2), and construct a photocatalytically regenerative carbon filter for 100% water recovery. The premise is that the activated carbon, coated with TiO2, will capture the compounds through traditional filtration and adsorption. Once the carbon becomes exhausted, it can be regenerated in-situ by turning on the UV lamps thereby activating the photocatalyst.

Post-treatment of anaerobically digested residue produced during long term space missions was investigated. Solid waste was anaerobically digested by employing the SEBAC system. One of the goals of post-treatment step is to convert ammonia in the residue to nitrates via biological nitrification processes. It was found that anaerobically digested residue contained nitrifying microorganisms which could be activated by aeration. Without supplying any external nitrifying inoculum, nitrification was initiated within 2 days by continuously blowing air at 15 ml/min. The maximum rate was 0.78 mg /g dry weight /day. However, denitrification process occurred soon after nitrification and ∼ 50% of nitrate was denitrified. A modified system in which aeration was carried out by holding air within the reactor at a pressure of ∼ 10 psi yielded a higher initial specific nitrification rate of 1.7 mg/g dry weight/day. Moreover, nitrification was initiated within a day.

A magnetically agitated photocatalytic reactor (MAPR) has been developed and tested as a post-processor in the past using phenol and reactive red dye to simulate these waste components, yet these components ignore factors that may hinder a photocatalytic post processor including competitive adsorption of various organic compounds and their oxidation byproducts and the demonstrated detrimental effect of inorganic compounds such as ammonium bicarbonate on photocatalytic oxidation. To assess these effects, this work looks at photocatalytic oxidation of air evaporation subsystem (AES) ersatz water while modifying the photocatalyst mass, magnetic field current and frequency to find the optimal conditions. Additionally, the magnetic photocatalyst has been characterized to observe the assembled structures formed when exposed to the magnetic field array in the MAPR and the crystallinity of the titanium dioxide coating.

The main principles of artificial atmospheric design for a Martian Greenhouse (MG) are described based on: 1. Cost-effective approach to MG realization; 2. Using in situ resources (e.g. CO2, O2, water); 3. Controlled greenhouse gas exchange by using independent pump in and pump out technologies. We show by mathematical modeling and numerical estimates based on reasonable assumptions that this approach for Martian deployable greenhouse (DG) implementation could be viable. A scenario of MG realization (in terms of plant biomass/photosynthesis, atmospheric composition, and time) is developed. A list is given of technologies (natural water collection, MG inflation, oxygen collection and storage, etc.) that are used in the design. The conclusions we reached are: 1. Initial stocks of oxygen and water probably would be required to initiate plant germination and growth; 2. Active control of MG ventilation could provide proper atmospheric composition for each period of plant growth; 3.

Previous work demonstrated that the Photo-Cat® developed by Purifics is capable of reducing the total organic carbon (TOC) concentration of 51 mg/L to below 0.5 ppm using Degussa P25 titanium dioxide (TiO2) as a photocatalyst. The work also showed that ammonium bicarbonate had a detrimental effect on the rate of photocatalytic oxidation, but did not prevent the system from reaching the potable water specification. Nanometer sized Degussa P25 is very popular and quite frequently used as a benchmark of performance in literature, but it may not be the most effective for oxidizing all waste streams. It is critical that each component of the water recovery system be optimized for power consumption and the effectiveness of the photocatalyst plays an important role in accomplishing this.

The photocatalytic oxidation of VOCs was investigated using a novel countercurrent flow reactor designed to enable the treatment of toluene present in the gas and the aqueous phases simultaneously. The reactor was packed with silica-titania composites commingled with plastic pall rings. Using this mixed packing style was advantageous as it resulted in a higher UV penetration throughout the reactor. The average UV intensity in the reactor was determined to be 220 μW/g irradiated TiO2. It was found that under dry conditions, the STCs had a high adsorption capacity for toluene; however, this adsorption was completely hindered by the wetting of the STCs when the two phases were flowing simultaneously. The destruction of toluene in the aqueous phase was determined to follow a linear trend as a function of the contaminant concentration.

The partial electrochemical reduction of carbon dioxide (CO2) using ceramic oxygen generators (COGs) is well known and widely studied. Conventional COGs use yttria-stabilized zirconia (YSZ) electrolytes and operate at temperatures greater than 700 °C. Operating at a lower temperature has the advantage of reducing the mass of the ancillary components such as insulation and heat exchangers (to reduce the COG oxygen output temperature for comfortable inhalation). Moreover, complete reduction of metabolically produced CO2 (into carbon and oxygen) has the potential of reducing oxygen storage weight if the oxygen can be recovered. Recently, the University of Florida developed novel ceramic oxygen generators employing a bilayer electrolyte of gadolinia-doped ceria and erbia-stabilized bismuth oxide (ESB) for NASA's future exploration of Mars.

Efforts to develop sensor and control system technology to monitor air quality for life support have resulted in the development and preliminary testing of a concept based on expert systems and ion trap mass spectrometry (ITMS). An ITMS instrument provides the capability to identify and quantitate a large number of suspected contaminants at trace levels through the use of a variety of multidimensional experiments. An expert system provides specialized knowledge for control, analysis, and decision making. The system is intended for real-time, on-line, autonomous monitoring of air quality. The key characteristics of the system, performance data and analytical capabilities of the ITMS instrument, the design and operation of the expert system, and results from preliminary testing of the system for trace contaminant monitoring are described.