Enhancement of biogas production from pineapple waste by acid-alkaline pretreatment

Abstract

Abstract The present study examined the effect of acid-alkaline pretreatment on pineapple waste for the performance on the anaerobic digestion. The acid-alkaline pretreatment was carried out by varying pH values from 2 to 12 using HCl and NaOH, and the mixtures were agitated at 250 rpm with the contact time of 24 hrs. The overall result showed that SCOD concentrations increased when pH values were increased. The value of biodegradability of raw waste was about 0.304. The BOD/COD ratios increased to 0.439 and 0.473 for pH 7 and pH 9, respectively. However, the BOD/COD ratios decreased for adjusted pH 12. For BMP test at pH 7, the removal efficiencies were 76.34%, 91.69% and 84.69% for TS, VS and COD, respectively, which were the higher efficiency than other conditions. It was also the optimal condition for the gas production rate because the pretreated pine apple waste was hydrolyzed much the organic matter into the soluble forms that can be immediately consumed by the anaerobic digestion process.