| TE supplementation | Food wastes supplemented with Fe, Co, Mo and Ni | Addition of TEs stopped VFA inhibition | [49] |
| TE supplementation | Food wastes supplemented with Fe, Co, and Ni | Addition of TEs gradually decreased VFA inhibition and maintained process stability, and allowed higher organic loading operations | [50] |
| TE supplementation | Food wastes supplemented with Se and Co | Se and Co supplementation in food wastes digestion prevented VFA accumulations, increased methane yields and resulted in stable operations | [53] |
| Co-digestion | co-digestion of FW (83%) and PW (17) | The highest concentrations of TE in piggery wastewater almost doubled the methane production and prevented VFA accumulations | [54] |
| Co-digestion | Food waste (66.7%) mixed with cattle manure (33.3%) | TE available in cattle manure; Mg (4.99%), Ca (2.27%), Mn (950 ppm) and Zn (250 ppm) increased total methane yield by 42% | [55] |
| GAC supplementation | Synthetic wastewater supplemented with coal-based GAC | GAC supplementation enhanced methane productions, biomass growth, and acclimatization of microorganisms | [56] |
| GAC supplementation | VFAs (acetate, propionate, and butyrate) supplemented with GAC | GAC addition enhanced VFA degradation and increased methane yields | [57] |
| GAC supplementation | OFMSW supplemented with GAC | GAC supplementation increased syntrophic associations between bacteria and methanogens | [58] |
