(249b) Hydrothermal Gasification of Concentrated Blackwater to Produce Energy and Low-Tier Water

The production of energy and low-tier water from blackwater was demonstrated at bench-scale through solids concentration, hydrothermal gasification, and subsequent wastewater treatment. Current wastewater disposal in remote environments is complex, expensive, and requires significant energy and resources. Conventional gasification of wet wastes is not feasible due to the high energy input required to remove and process water. However, Mainstream has developed a novel utilization of wet waste using combined hydrothermal gasification and physical water treatment systems which provides utility and relieves the disposal burden. This process is based around concentrating the solids through high-efficiency hydrocyclones, enabling the majority of the blackwater solids to be concentrated into a small fraction of the water. Ensuing gasification experiments showed >99% of organic material was converted into a low-BTU, flammable gas. The remaining water was then treated to meet low-tier water criteria. Energy analysis revealed that the system can produce net energy at a wastewater processing rate of over 1,000 gal/day, with >95% of incoming wastewater treated to be suitable for low-tier applications. Based on the bench-scale testing and system analysis, a preliminary full-scale design was developed to integrate subsystems and estimate costs. This presentation will discuss the novel water treatment process, energy and mass balances, hydrothermal gasification parameters and yields, and overall economics.