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ISS SGO (sanitation & hygiene)

Sanitation is included under the acronym of SOZH, СОЖ – Life Support Systems – along with water and food (the last two are described on a separate page) and is part of the primary life support system located in Zvezda.

The sanitation and hygiene equipment (SGO, СГО) is located in Zvezda, in a compartment aft of the starboard cabin (kayuta, каюта). (Sadly, there is no window for occupants to look out of while occupied.) The main component of this is the toilet (or ASU, АСУ in Russian). A hand-washer was in the original design, but was deleted as it was too awkward to use.

As there is no gravity for things to fall, vacuum suction is used to draw away waste. Liquids and solids are treated separately and stored in silver cylindrical containers; both are disposed of when a Progress cargo ship departs and burns up in the atmosphere. Urine was recycled on Mir but the Russian toilet on the ISS does not have this capability.

The toilet is of the same well-tested design used on Mir (it is manufactured by RD & PE Zvezda); this was apparently preferred by the Space Shuttle astronauts to the Orbiter’s own toilet when docked to Mir. In July 2007, NASA was to pay Energiya $19 million to manufacture a toilet system that would be installed in the U.S. segment in 2008, to support a crew of 6 beginning in 2009. The new toilet would augment the old one; unlike the latter the new toilet will be able to filter and purify urine into potable water (likely to be used for the Elektron oxygen device).

Once a week, usually on Sundays, toilet flush readings data is downlinked to TsUP (which means that each crewperson’s daily visits are monitored!). There is also inspection of the urine collection (SP, СП) & pretreat assembly and water supply status (SVO, СВО) counter readings.

Tidbits from On-Orbit Reports:

OOR 17 March 2005

The crew worked on the SOZh environment control & life support system, completing the regular daily maintenance and performing significant repair on the ASU toilet facilities, which experienced a failure of its urine collection system overnight. The failed urine collection valve was successfully replaced with a spare. (When the ASU facilities are down, the crew can temporarily use the Soyuz toilet.)

OOR 13 May 2005

The CDR serviced the ASU toilet facility, replacing the pretreat container (E-K, ЭК) plus hose with a new assembly, discarding the old one. (E-K contains five liters of pre-treat solution – a mix of H2SO4 [sulfuric acid], CrO3 [chromium oxide, for oxidation and purple color], and H2O [water]. The pre-treat liquid is mixed with water in a dispenser [DKiV, ДКиВ] and used for toilet flushing.)

More details (LSS ISS)

Diagrams & photo links

Diagrams from the Russian Popular Mechanics article linked below:

  • ASU schematic diagram (172 KB, external link)

  • The ASU 8A was used at the orbital station Mir from 1986 to 1987. The current ASU ЕM in the ISS Zvezda module is an evolutionary development of this system.

    Diagram translation:

    Мочеприемник «Писсуар» им пользуются когда надо сходить в туалет только по-маленькому
    Urinal relief-tube
    Емкость для твердых отхоодов
    Solid waste container/storage
    Приемник твердых и жидких отходов утитаз
    Solid and liquid waste receivers/storage
    Емкости для сбора урины
    Urine collection tanks
  • Inside view of urine collection tanks on Mir. An absorbent substance (пенополивинилформаль, expanded polyvinylformal [or polyvinylformaldyhide]) was used to increase storage capability.

Patrick Sinnott sent me a lot of ISS ASU photos! They are stored here in an external photo album. Direct links to the photos:

  • Interior photos of the sanitation compartment: ISS01E5167 (with Yurii Gidzenko), ISS002E5026, ISS002E5027, ISS002E5028, ISS002E9578, ISS002E9579, STS106-303-022, STS106-303-023
  • JSC2000E04156, JSC2000E17734: ISS SM toilet
  • Seat assembly: JSC2001E27933, JSC2001E27934, JSC2001E27935, JSC2001E30016
  • JSC2000E14415: urine collection system panel
  • JSC2000E17676: urine collector
  • JSC2001E13085: female urine collection cup
  • JSC2001E13093: male urine collection cup
  • JSC2001E13088: solid waste collection bag. It locks on to a ring under the toilet/commode seat and dangles inside the silver KTO container. When you are finished you just tug on the red tab. That action unseats the bag from the seat lip and airflow pulls the bag inside the KTO container. The red tab is connected to a drawstring encircling the bag’s opening. As the bag is sucked into the KTO you hang on to the red tab and the bag pulls itself shut, when it shuts you let go and it disappears inside the KTO.
  • Urine receptacle stowed (vertically next to the toilet at right)
  • ISS003E6507, ISS003E6508, JSC2001E27911, ISS002E5336: Pictures of the EDV and KTO containers. EDVs are used to store water for drinking, Elektron and the Flush water tank component of the ACY system. When they are empty they are then used in the ACY for urine storage. The EDV comes in two pieces, the bucket/body and the lid with it's attached bladder. They are launched separately, again, a neat design, the buckets nest within one another to save space. The KTO container is the one with the big central lid and a smaller side port. It comes in two pieces like the EDV but there is no bladder.
  • ISS010E12721, ISS012E06290: Salizhan Sharipov and Valerii Tokarev showing the clear plastic bladder of the EDV full of water
  • JSC2002E28921, JSC2002E28932: EDVs and KTOs stowed for launch in the pressurized payloads compartment of a Progress

Related page: Soyuz ASU

~ Page last revised: 8 March 2008

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Views of the ISS ASU ground model