Spent coffee grounds valorization through pyrolysis for energy and materials production in the concept of circular economy

Abstract

The aim of the paper is to investigate the recovery of useful material and energy from waste, in the context of circular economy, by studying pyrolysis of spent coffee grounds, for the production of fuels and carbon materials such as biochar, to be further used as fertilizer in arid fields, thus closing loops in agriculture. Pyrolysis was carried out at temperature ranging from 400 to 700 ° C with a heating rate of 50 °C/s, at atmospheric pressure and inert atmosphere. The results have shown that a maximum yield of biooil can be achieved at 540° C (36 wt%) where the gas reached a yield 9 wt% and the char reached the 29 wt%. At 700 ° C, where oxidation reactions mainly take place against of cracking (gasification), gas yield reached 29 wt%, while biooil and char reached 20 wt% and 26 wt%, respectively. These preliminary data can challenge decision making in introducing sustainable food waste management strategies where pyrolysis can be the conversion pathway.