Conceptual Development of a Hybrid Life Support System Integrating a Biological Wastewater Processor with a Plant Growth Unit

Abstract

Hybrid life support systems which combine biological processes with physical/chemical systems can offer more sustainable overall life support architecture that reduces long term resupply costs and provides dis-similar redundancy increasing reliability. Hybrid life support systems can include numerous technologies but in general development of the biological portion has either focused on plant growth for food production and air processing or bacterial based bioreactors for wastewater treatment. Each system offers benefits to life support architectures but also individually have limitations and/or issues that reduce their overall benefits. Integrating plant based and bacterial based systems may provide significant synergies and reduce negative issues related to each technology individually. Our objective was to produce a conceptual design of an integrated biological wastewater processor with a plant growth system. The system would utilize a micro-gravity compatible bioreactor (MABR) to treat greywater (HC, Hygiene, Shower and/or Laundry) to supply the plant growth system with hydroponic make up water. The plant growth system would produce potable water as distilled plant condensate as well as proved salad and fresh vegetables. The MABR would remove organics from the wastewater which otherwise prevent its use as a hydroponic solution due to excessive bacterial growth that would occur. This would reduce the need to use potable water and would allow the production of an equal volume (up to ~40 kg/d) of distilled plant condensate. Excess CO2 from the bio-processor could be vented to the plant chamber reducing the CO2 load to the cabin and increasing growth rates, while O2 produced by the plant growth chamber could be used to support the MABR reducing consumption of stored or produced O2. We will present the design of the integrated system as well as an analysis of the mass, volume, and power requirements and compare these to non-hybrid life support systems and/or resupply.