Abstract
•Food waste derived hydrochar was compacted with molasses or molasses/lime.•Solid bridge formation and agglomeration were resulted from molasses and lime.•Hydrochar from high hydrothermal severity with binders had excellent properties.•Molasses pellets had higher combustion reactivity than the molasses/lime pellets.
Hydrochar was produced from food waste under varying hydrothermal carbonization (HTC) conditions, and was pelletized using molasses and molasses/lime binders for fuel pellet production. The physico-chemical properties, density, mechanical properties, and water resistance, and combustion characteristics of the hydrochar pellets were investigated. The results indicated that molasses pellets and molasses/lime pellets exhibited increased compressive strength, density, and impact resistance due tothe “solid bridge” that formed from molasses recrystallization and agglomeration by lime. The hydrochar samples prepared at 230 °C and 260 °C, with long residence times of 8 h, showed excellent compressive strength and impact resistance index (IRI). Both molasses pellets and molasses/lime pellets exhibited slightly increased equilibrium moisture content (EMC), with the former showing a high water-resistance index (WRI) in the immersion test. Thermogravimetric analyses indicated that the molasses pellets had a lower ignition temperature and higher combustion interval than those of the molasses/lime pellets.