The Effect of Alkaline Pretreatment on Biogas Productivity and Kinetic from Cocoa Pod Husk Waste Using Batch Reactor

Abstract

Cocoa pod husk (CPH) as a potential plantation waste was used for the biogas production. Pretreatment using NaOH (N), NaOH with addition of H2O2 simultaneously (NHs) and consecutively (NHc) were carried out to remove lignin content in CPH and enhance methane yield. 2% NaOH was used for N pretreatment for 30 minutes at 121oC. In other hand, NaOH with H2O2 concentration of 5% (w/w) was used for NHs and NHcpretreatment for 75 minutes in shaker incubator (30 oC, 130 rpm) where the pH was set at 11.5 using 6 M NaOH. All pretreatment was done in three different biomass concentrations (5, 10, 15%). The highest delignification of 79.26%, 91.73% and 89.09% were obtained from N, NHS and NHcpretreatment, respectively. Biogas production from CPH pretreatedNHS resulted in higher methane yield (0.0389 m3CH4/kgVS) than other pretreatments which 181.76% improvement corresponding to non-pretreatment CPH and the productivity was 0.0009 m3CH4/kgVS.day. Kinetic study for each variable using the modified Gompertz equation was investigated which the coefficient of determination (R2) values above 0.99 were obtained..