Filter-Reactor Catalytic Oxidation

The system for water recovery from humidity condensate has been upgraded for the International Space Station (ISS) and includes an assembly that will remove organic contaminants by catalytic oxidation in an air-liquid flow at ambient temperature and pressure upstream of the multifiltration bed. This should at least double the life of the multifiltration beds (Samsonov et al. 1997). The composition of the catalyst and the process is proprietary. In fact, this “filter reactor, ” an ambient-temperature catalytic reactor, has been in operation aboard Mir since January 1998.

In the service module design for the ISS, the system will have a condensate feed unit that will facilitate transfer of condensates collected from ISS modules (and stored in contingency water container bags) to the Russian condensate processor for water recovery.

Urine Processing

A Russian system for reclaiming water from urine has been in operation aboard Mir since January 1990. This system was designed primarily for regenerating cabin oxygen through electrolysis. The urine-processing system consists of three parts: urine preparation (collection, preservation-pretreatment, storage), atmospheric distillation, and distillate treatment and purification. These subsystems are described briefly below.

The Mir urine preparation subsystem consists of the urinal, a urine-pretreatment assembly, and a blower. Urine is distilled at atmospheric pressure in a distillation unit that consists of an evaporator, condenser, heater, and brine tank. The distillate post-treatment and purification unit is identical to the humidity condensate processor. The urine is treated with sulfuric acid and a liquid solution of a commercially available oxidizer (similar to Oxone, described below), and the treated urine undergoes membrane distillation at atmospheric pressure and at relatively low temperatures. An electric heater raises the temperature to 50-52°C, and water is evaporated with a stream of air that blows at 100 L/min through the evaporator, which consists of a stack of hydrophilic capillary-porous polymeric membranes. The water vapor is condensed in a heat exchanger, cooled by an onboard coolant, and the condensed

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