Mechanical compression assisted heat drying of space solid waste: Dewatering performance and volatile pollutants identification

Hot melt compression treatment is a new technology in which traditional pressure dehydration is combined with thermal effects to achieve improved liquid/solid separation with low energy consumption. A dewatering process combining the mechanical expression with the heating treatment of space solid waste is proposed in this paper. Temperatures of 130-180 °C and a mechanical load of 0-8 MPa were employed on the drying behavior of space solid waste and product distribution with a self-designed hot press experimental setup. Experimental results showed that mechanical compression employed at increased temperatures had revealed a significant benefit in water recovery, resulting in the highest reduction of 95.5% of the moisture content. Considering the dehydration efficiency, the dewatering process of solid waste showed a positive effect at 160 °C and 6 MPa with a residence time of 100 min. At the same time, the reusability and chemical evolution were characterized comprehensively. The results showed that the condensed water had great potential to be reused as drinking water in the space station. Moreover, from an integrated perspective involving gaseous emissions, oxygen-containing functional groups accounting for 51.58-76.01% were the main components of the gas products. Halohydrocarbon was identified as the key volatile pollutant during the process of hot compression. In conclusion, this study gives a detailed insight into the hot melt compression behavior of space waste and offers potential opportunities and benefits for space solid waste treatment.