Anaerobic digestion and the effect of hydrothermal pretreatment on the biogas yield of cocoa pods residues

Integrating anaerobic digestion and slow pyrolysis improves the product portfolio of a cocoa waste biorefinery

“…It follows that the mass-loss upon mono-digestion, being 21 wt.%, constituted ca., 50% of the available carbohydrate matrix 29 . Antwi et al 24 also observed a biodegradability index (i.e., the observed biogas yield over theoretic biogas yield) between 41% to 47% (cellulose had a digestibility index of 84%). This indicates that the digestate will be lignin-enriched.…”

“…Cocoa pod husks, like other lignocellulosic biomasses, are converted to biogas upon digestion to only a modest extent 24 . In many cases, the methane yield after anaerobic digestion of lignocellulosic biomass only amounted to 60% of what theoretically can be expected.Co-digestion with manure, like in Dahunsi et al 25 , Acosta et al 26 , proved effective to obtain elevated biogas yields without any pretreatment 17 .…”

Insight into Pretreatment Methods of Lignocellulosic Biomass to Increase Biogas Yield: Current State, Challenges, and Opportunities

“…On the other hand, Luo et al [143] examined hydrothermal pretreatment of rice straw at different temperatures from 90 to 130 • C. Both 100 • C and 130 • C pretreatments presented similar methane yield of 127.6 and 124.6 mL/g VS, respectively, which were 22.90% and 19.83% higher than untreated rice straw. Antwi et al [144] evaluated hydrothermal pretreatment on cocoa pods residues at temperatures in the range of 155-220 • C and at reaction time between 5 and 15 min and reported an optimum methane yield of 526.38 mL/g VS at 150 • C for 15 min and opined that higher severity conditions resulted in lower biogas yield.…”

Bioenergy from biofuel residues and waste

“…Antwi, Engler, Nelles, and Schüch (2019) studied increasing the biogas yield of cocoa pod residues through hydrothermal pretreatment. They varied temperature and reaction time from between 150–220°C and 5–15 min, respectively.…”