Treatment of Spacecraft Wastewater in a Submerged-Membrane Biological Reactor

A submerged membrane biological reactor (MBR) was evaluated for treatment of a spacecraft wastewater analog. The aerobic MBR (a modified CSTR) had a 12 L working volume, submerged 0.2 μm membrane filter, 12.6 h hydraulic retention time (simulated 2 person crew), and infinite solids retention time. Simulated graywater contained a urine analog and two surfactants: disodium cocoamphodiacetate and sodium laureth sulfate (461 ppm of active ingredient, combined). Two MBR runs of 60- and 10-day durations were completed with different conditions (startup: 16 d vs. 3 d, pH control vs. none). Influent, effluent, and mixed liquor were analyzed for COD, BOD, TSS, surfactant concentration, and microbial load and activity. BOD removal averaged ≥ 92% for each run with 100% surfactant degradation but no detectable nitrification. The food to mass (F/M) ratio decreased over time. Surfactant decomposition is feasible with a small-scale MBR, although changes are needed to promote nitrification.