Mixing equal amounts of algal biomass and food waste leachate (1A:1F) led to lower methane production than the two-component combinations with raw sludge (1S:1F and 1S:1A). Co-digestion with equal amounts of all three substrates (1S:1F:1A) led to the greater methane production at day-42 than all other three component mixtures (4S:1F:1A, 1S:4F:1A, and 1S:1F:4A). These results can be explained by the different biodegradability of the different
substrates, and suggest that raw sludge contained more digestible organic matter than the other substrates. Due to the different biodigestibility of the three substrates in this study, co-digestion is clearly a better option.