The effect of key factors on anaerobic co-digestion of leachate and crude glycerin by statistical design of experiments

Anaerobic digestion is a versatile biotechnology because of the energy recovery from different kinds of waste. In addition to anaerobic digestion, there is the anaerobic co-digestion process, which improves the energy recovery of many kinds of waste in a single installation. The association of landfill leachate and crude glycerin is promising, considering the respective characteristics of each one. However, data about the anaerobic co-digestion of these substrates is still scarce. In this context, the present study aimed to evaluate the effect of the factors: incubation time (20-40 days), pH (7-8), glycerol proportion (0.5-2.5% v/v) and substrate/inoculum ratio (0.2-0.6 g COD g-1 VSS) by Plackett-Burman statistical design of experiments. The advantages of anaerobic co-digestion were evaluated achieving the highest treatment performance of 98.1% efficiency of organic matter removal, and a high methane content in the biogas of approximately 79%. Furthermore, a positive effect of the key factor incubation time and glycerol proportion, instead of the substrate/inoculum ratio, which requires low values. Overall, the following parameters: incubation time, glycerol proportion and S/I ratio highlighted their significant effect in the bioprocess performance.