Biochemical methane potential of food and garden waste co-digestion with variation in solid content and inoculum:substrate ratio

The objective of this study is to evaluate the influence of the addition of garden waste (GW) on the performance of food waste (FW) anaerobic digestion. In this regard, a bench scale experiment was performed via biochemical methane potential test. The reactors were composed of flasks with a total volume of 310 mL and a useable volume of 120 mL, containing the waste mixtures in the different studied conditions. All reactors were incubated under 36 °C. A factorial design was used to evaluate the influence of three factors on methane production: inoculum and substrate ratio (I:S), volatile solid (VS) content of the mixture and type of substrate. The results indicated that the condition referred to an I:S ratio of 1:1, higher VS content (VS mix ) and only FW as a substrate achieved the higher methane production and differed significantly from the others. This combination resulted in 67.5% of VS removal, 509 NmL of cumulative CH 4 and a specific methane yield of 159 NmLCH 4 gVS −1 . The results obtained in this research indicated that the addition of GW on the anaerobic digestion of FW did not positively influence the methane production. Graphic abstract