Torrefaction Processing for Human Solid Waste Management

New technology is needed to collect, stabilize, recover useful materials, and store human fecal waste for long duration missions, both for crew safety, comfort and resource requirements and planetary protection. The proposed SBIR Phase I project addresses an innovative torrefaction (mild pyrolysis) processing approach that can be used to sterilize feces, control odor, and produce a stable, free flowing powder that can be easily stored or recycled, while simultaneously recovering all of the moisture, producing additional water, and only small amounts of other gases (CO2, CO, CH4) and liquids. The overall objective of the Phase I program is to demonstrate the feasibility of a near full (1/3) scale integrated Waste Collection/Torrefaction (WC/T) unit for fecal waste streams. The Phase I work will be accomplished in three tasks: 1) test unit design and construction; 2) laboratory testing on relevant waste streams; 3) evaluation and preliminary Phase II prototype design. This work plan will address the key questions about the WC/T unit feasibility for the application to human fecal waste and related solid waste streams. In addition, the torrefaction method can be applied using the same or similar conditions to other types of wet or dry cellulosic biomass (food, paper, wipes, clothing) which provides for some desirable redundancy in the waste management system. The Phase II prototype will be compatible with the Universal Waste Management System (UWMS) and complementary to the Heat Melt Compactor (HMC), both now under development by NASA. The torrefaction process can also be accomplished with minimal crew interactions, modest energy requirements and will be able to tolerate mixed or contaminated waste streams.