Products

By-product streams:

1. Solid-liquid separation: Sludge-like matter
2. PHB separation: Water stream containing some VFAs and PHB stream (plastic for 3D printing)

Treatment of by-products to produce useful materials:

the sludge-like by product can either be fed into the general wastewater processing unit and be combined with the other sludge for treatment, or it can be treated using the process Torrefaction (mild pyrolysis). The two streams that would leave the torrefaction processing unit (TPU) are water with some VFAs and the black, solid matter (char). Our team believes that torrefaction is the most efficient approach to treatment of the sludge-like matter as the final product (char) holds a couple of benefits:

• biologically stable - doesn’t support biological activity
• process allows for production of pyrlytic water – meaning extra water recovery
• can be used as a building material
• can be used for radiation shielding
• can be used as a food substrate
• can be used as a carbon/hydrogen storage

The torrefaction technology is just emerging and was not yet tested large scale, however a couple of papers (M. Serio, J. Cosgrove, M. Wojtowicz, 2016), (M. Serio, M. Wojtowicz, K. Wignarajah, 2014)) by NASA outline the potential of the system and see it as a promising solution for the sludge management in space and on Mars.

Our team suggests that the water and VFAs by-product stream is fed into one of the final stages of the water processing unit (WPU), where it can be cleaned to the required water quality standard. Such treatment allows to close the water loop in the feces treatment (recycle all the water).