The pungency impact of 6-gingerol on the methane generation from food waste by anaerobic digestion: batch and two stages performance

Abstract 6-gingerol, a spicy active ingredient present in ginger, widely exists in food waste. Herein, the mechanism followed for the anaerobic digestion of 6-gingerol in food waste has been investigated. Experimental results showed that 6-gingerol could enhance methane production from 0.80% to 18.32% under a concentration of 10-30 mg/gVS. However, the cumulative methane yield decreased by 66.28% and 71.86% when the 6-gingerol concentration was 40 and 50 mg/gVS, respectively. The concentrations of volatile fatty acids, soluble chemical oxygen demand, carbohydrates and proteins in 6-gingerol-treated groups were slightly higher than in control, indicating that 6-gingerol might facilitate the release of organics into mixed liquor. Sequencing analysis revealed that the addition of 6-gingerol could inhibit the growth of acetoclastic methanogens and enhance the abundance of hydrogenotrophic methanogens. Studies on different stages showed that the extent of inhibition of methanogens associated with 6-gingerol was higher than that of the acidification stage.