Assessment of the effect of drying temperature and composition on the biochemical methane potential of in-house dried household food waste

Abstract

Household food waste management and treatment has been recognised as a significant issue worldwide and at a European Union level. Source-separation of household food waste following drying at source presents a viable solution to this problem. The present research aims at investigating the effect of drying of model household food waste at different temperatures (i.e. 63 ±3 °C and 83 ±3 °C) on its biochemical methane potential. The drying process was carried out using a prototype household waste dryer. The model sample consisted of 77%w/w vegetables and fruits (48%w/w and 29%w/w, respectively), 12%w/w pasta/rice, 6%w/w meat and fish, 3%w/w bread and bakery and 2%w/w dairy. Moreover, drying at the same temperatures was applied for two household food wastes samples with different composition, in order to assess the influence of the samples’ composition on both the drying process and the methane generation. For all temperatures used, the higher %w/w mass reduction was observed for model waste (MD) (67.39%w/w and 75.79%w/w for 63 °C and 83 °C, respectively), then for rich-in-protein content (PRO) (66.18%w/w and 69.73%w/w for 63 °C and 83 °C, respectively) and finally for rich-in-fat content (FAT) samples (54.35%w/w and 66.31%w/w for 63 °C and 83 °C, respectively), which confirmed the effectiveness of the drying process. The biochemical methane potential experiments have confirmed that the substrate produced the highest methane yields was the FAT, producing 524.25 ±2.86 L CH4 kg-1 volatile solids.