Material Recycling through Animal Intestinal Micro Organisms in a Closed System

A material recycling or circulating system is an essential component of a Controlled Ecological Life Support System (CELSS) in a closed space such as in space, on the moon or in the deep sea. The system is divided into two types: one is a biosystem and other one is a non-biosystem or pure chemical-type. Both have advantages and disadvantages, respectively. In a previous report, we have reported a microalgal culturing system for CO₂ elimination and O₂ regeneration or a so-called life support sytem, in closed air on the ground by using the photosynthetic alga, Euglena gracilis. z. The present study was initiated to establish an optimal design for a microorganism-reactor for a material circulating system, especially for feces, garbage and sewage in a CELSS.

We focused on the microorganisms in the present culturing system. We investigated to find the best microorganisms for a material circulation system that functions effectively in the CELSS. We found that animal intestinal microorganisms showed the maximum elimination rate for feces, garbage and sewage. We determined the elimination rate of ammonium ion from the water mixed waste feces of livestock. We found that we could achieve 30% ammonium ion elimination in the reaction tank within 24 hours and there was no bad odor remaining about 1 hour after addition of waste feces. Furthermore, the BOD value in the reaction tank decreased 80 % within 24 hours. Connection of the microalgal culturing systems for CO₂ elimination and O₂ regeneration and the present microorganism-reactor system is expected to realize the establishment of a balance of long term material circulation through optimal material circulation control, allowing for the coexistence of humans, animals and plants without any material exchange from the outside. Furthermore, this principle is very important for establishing new life styles suitable for a zero-emission society.