Comparative assessment of the methanogenic steps of single and two-stage processes without or with a previous hydrolysis of cassava distillage

Abstract

In this study, cassava distillage with a high solid content was digested in an anaerobic sequencing batch reactor (ASBR) without or with a previous hydrolytic step by a cellulolytic microbial consortium (i.e., single or two-stage process). The methanogenic steps of these processes were compared and evaluated through observation of the methanogenic stability and methane yield under different organic loading rates (OLRs). It was found the methanogenic reactor can be stably performed with the OLRs lower than 20 g COD L(-1) d(-1) in the two-stage process, where a specific methane yield (0.147 L CH4 g(-1) CODremoved) could be achieved, which was 17.6% higher than that of the single-stage process (0.125 L CH4 g(-1) CODremoved). The above results indicated that the degradation of cassava distillage in a two-stage process with a previous hydrolytic step can assure the methanogenic process proceeds with greater stability and generates higher methane yield.

Keywords: Cassava distillage; Hydrolytic step; Microbial consortium; Organic loading rate (OLR); Two-stage process.