Efficient Use of Micro-Algal Bioreactor for Carbon and Nitrogen Recycling in Closed System

A material recycling or circulating system is an essential component of a Controlled Ecological Life Support System (CELSS) in a closed system such as in space, on the moon or in the deep sea. The present study was initiated to establish an optimal design for a microorganism-reactor, so-called compost, for a material circulating system, especially for feces, garbage and sewage in a CELSS. We found that intestinal microorganisms from livestock created the best results for compost from feces, garbage and sewage. In the present experiments, we used two types of bioreactors: one is a solid processor and the other is a liquid processor. Product from both reactors were satisfactory as organic fertilizer for plants in the system. Combining the micro algal culturing systems for CO₂ elimination and O₂ regeneration and the present microorganism-composting 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, in space as well as agricultural systems in the field.