Hydrothermal Liquefaction as a Means for Resource Recovery from Wet Waste

The recent results in hydrothermal liquefaction (HTL) of wet wastes have demonstrated progress in process development and potential for actual application at scale. Although much has been published about batch reactor tests of HTL, there is only limited information yet available on continuous-flow processing tests, which can provide a more reasonable basis for process design and scale-up for commercialization. High-moisture biomass feedstocks are the most likely to be used in HTL. These materials are described and results of their processing are discussed. The recovery of the carbon as useful fuels, liquids and gaseous, is the prime factor for using the technology, while other resource recovery, such as the water, nitrogen, and phosphorus, are also considered. Engineered systems for HTL are described as is their scale-up to demonstration at market scale of operation. With the results available, process models have been developed, and mass and energy balances determined. From these models, process costs have been calculated and provide some optimism as to the commercial likelihood of the technology.