Loading Balance and Influent pH in a Solids Thermophilic Aerobic Reactor 2005-01-2982

The application of biological treatment to solid waste is very promising to facilitate recycling of water, carbon, and nutrients and to reduce the resupply needs of long-term crewed space missions. Degradation of biodegradable solid wastes generated during such a mission is under investigation as part of the NASA Center of Research and Training (NSCORT) at Purdue University. Processing in the solids thermophilic aerobic reactor (STAR) involves the use of high temperature micro-aerobic slurry conditions to degrade solid wastes, enabling the recycling of water, carbon, and nutrients for further downstream uses. Related research presently underway includes technical development and optimization of STAR operations as well as a complementary evaluation of post-STAR processing for gas-stream purification, water recovery by condensate purification, and residuals utilization for both mushroom growth media and nutritional support for fish growth.

In optimizing the STAR system, factors including solids loading, influent characteristics, and operational parameters can all impact the efficiency of the system. There will be a threshold solids concentration above which failure of the system will occur. In the evaluation of STAR to determine this ceiling loading concentration, the related importance of initial pH of the influent during start-up and the potential use of initial pH control was studied. This document will present an overview of recent progress and performance results for this STAR system, including the effects of solids loading and pH on performance.