Simulated wastewater, known as early surface mission wastewater, treated in previous experiments at JSC and TTU included urinal flush water, shower water, humidity condensate, oral hygiene water, and hand wash water. In reality, there is a difference between the early surface mission wastewater and the International Space Station wastewater. The ISS does not have a shower or hand wash, which contributes approximately 59 percent of the make-up water treated. The average influent ammonia concentration in the simulated wastewater treated by the TTU water reclamation system frequently exceeds 500 mg/L. Removal of the shower make-up water in simulated wastewater will result in a significant increase in the ammonia concentration, resulting in higher influent pH values and ammonia concentrations that may be inhibitory. Biological treatment technologies have suitably treated the diluted waste stream but a more concentrated waste stream may present a greater challenge. Therefore, the performance of a biological wastewater treatment system, consisting of a nitrifying membrane-aerated biological reactor (AMR) coupled with a denitrifying packed bed (PB) reactor, was evaluated. Treatment goals were 50 percent ammonia reduction and 95 percent DOC removal, which had been achieved with previous systems.
The AMR-PB system has been in operation for several months. For an average DOC influent concentration of 1236 mg/L, the system achieved 91 percent DOC removal. Approximately 32 percent of the influent total nitrogen (1762 mg/L) was removed during treatment. The results of the study indicated treatment efficiency was related to the characteristics of the wastewater. DOC and alkalinity were limiting in the wastewater.