Abstract:
The objective of this research was to study the effect of acid pretreatment on biogas production
from palm decanter cake by using hydrochloric acid or sulfuric acid (lab grade) concentration of
0.9, 1.5,5 and 10 % (w/w) and 1 :20 solid to liquid ratio (w/v). The experiment was divided into 2
parts. The first part was the acid pretreatment for 1, 2 or 3 hours either at room temperature (30?C)
or at 121?C with 0.1 Mpa of pressure. In the second part, the acid pretreated palm decanter cakes
that demonstrated a superior pretreatment efficiency were analyzed to determine their Biochemical
Methane Potential (BMP) and compared with that of untreated palm decanter cake. The results
showed that hydrochloric acid pretreatment demonstrated higher efficiencies than sulfuric acid
pretreatment. At room temperature and 10 % acid, hydrochloric acid pretreatment showed higher
%SCODITCOD increase by 9.9 %. Pretreated at 121?C and 10 % acid for 3 hours, hydrochloric acid
pretreatment showed higher %SCODITCOD increase by 21.7 %, comparing to sulfuric acid
pretreatment. Compared with untreated condition, the %SCODITCOD increased from 3.9 % to 73.9
%. The maximum BMP of palm decanter cake can be achieved by 5 % hydrochloric acid
pretreatment at 121?C for 3 hours, which was 51 % higher than the BMP of untreated cake. This
demonstrated the role of acid pretreatment on an improvement for biogas production yield of palm
decanter cake.