Semi-continuous anaerobic co-digestion of marine microalgae with potato processing waste for methane production

Abstract

The feasibility of using potato processing waste (PPW) as a co-substrate for co-digestion with a marine microalga (Tisochrysis lutea) was evaluated during semi-continuous co-digestion studies, in which the effects of digester start-up strategy (fed, and unfed) and PPW type (potato discarded parts, PPWdp; potato peel, PPWp) were examined. Results showed that methane yields were significantly affected by the start-up strategies used, with semi-continuous digesters that were immediate fed with 100% PPWdp or PPWp (fed start-up) showing significantly enhanced methane yields (337–374 mL CH4/g VS) compared to the digesters that were not initially fed either of these substrates (318–328 mL CH4/g VS). Co-digestion of T. lutea with PPWdp produced higher methane yields (328–374 mL CH4/g VS) than co-digestion with PPWp (318–337 mL CH4/g VS), but both feedstocks exhibited good potential for co-digestion with T. lutea. In addition, the fed start-up strategy and T. lutea co-digesting with PPWdp supported a high relative abundance of Methanosarcina. Overall, co-digestion with PPW could be a feasible method to reduce inhibition and enhance methane production when using marine microalgae as a feedstock for biogas production.