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A detailed study was conducted on nitrification using a bench top bioprocessor system proposed for water recycling of a urine-soap wastewater expected to be generated by crewmembers on International Space Station (ISS) or similar long-term space missions. The bioprocessor system consisted of two packed bed biofilm reactors; one anoxic reactor used for denitrification and one aerobic reactor used for nitrification. lnfluent wastewater was a mixture of dilute NASA whole body soap (2,300 mg/L) and urea (500 mg/L as organic nitrogen). During two months of steady-state operation, average chemical oxygen demand (COD) removal was greater than 95%, and average total nitrogen removal was 70%. We observed that high levels of nitrite consistently accumulated in the aerobic (nitrifying) reactor effluent, indicating incomplete nitrification as the typical end product of the reaction would be nitrate.

Iodine is being considered for disinfection of recycled hygiene and potable water in Space Station Freedom. Like chlorine, the halogen iodine can form disinfection by-products (DBPs) when used as a disinfectant in waters with dissolved or colloidal organic compounds. Recycled shower and laundry wastewater, urine and condensate from the space cabin atmosphere all have large amounts of dissolved and colloidal organic compounds and may generate iodinated DBP's which can be toxic to humans. We have investigated the formation of iodinated DBP's (IDP's) in model compounds typical of shower wastewater and condensate. The selection of these model compounds and flask experiments to test for IDP formation have been described. Methods for reaction, extraction and analysis for IDP's also have been developed. We have tentatively identified likely organic precursors from recycled water and several iodinated organic compounds formed during the reaction with iodine.