(334e) Use of the Aqueous Phase and Char from Hydrothermal Liquefaction of Biomass in Compost and Heavy Metal Adsorption Applications

Hydrothermal liquefaction (HTL) has shown much promise as a technique for converting waste biomass into bio-crude oil without the need for drying. Implementation of HTL at the large scale has been hindered by the limited options for value-added use of the aqueous phase (HTL-AP) and char (HTL-char) co-products.

This study investigated the applications of HTL-char as a mesoporous material for adsorption of heavy metals from water and of HTL-AP as an additive for compost. Food waste HTL-char, and a magnetic modified HTL-char prepared through co-HTL of food waste and red mud, were characterized and tested for removal of Pb and Cu from wastewater. Batch experiments were used to study the effects of magnetization, initial wastewater pH, contact time, and initial metal concentration on adsorption performance. Preliminary results from isotherm analysis showed that HTL-char derived from food waste has a higher adsorption capacity for Pb than for Cu. The maximum adsorption capacity of Pb (32.9 mg Pb g^-1 dry char) was obtained at pH = 3.5, T = 23.1°C, and initial PB concentration of 80 mg/L. The feasibility of utilizing HTL-AP to add moisture (and some carbon/nutrients) to compost was assessed in terms of the influence on microbial activity, nutrient availability (C/N ratio), humidity of the compost pile over the course of production, and quality of the finished compost.