Abstract:
This research aimed to study the effects of acid pretreatment on soluble COD and biogas production
from cassava decanter cake. The pretreatment was separated under 3 conditions. First, a sulfuric
acid concentration of 0 - 2.0 % (w/v) at room temperature (25 C) for 30 days. Second, a sulfuric
acid concentration of 0 - 0.5 % (w/v) at temperatures between 55 and 121 c for 15 - 60 minutes.
Third, a 0.045 molar of acetic acid, propionic acid, nitric acid or hydrochloric acid at 121 c for 30
minutes. The results showed that pretreatment with sulfuric acid at room temperature or at 55 c did
not significantly increase SCODITCOD. In contrast, pretreatment using only distilled water at room
temperature and pretreatment at 70, 90 and 121 c with sulfuric acid increased SCOD/TCOD to
19.3, 42.5, 81.0 and 83.4 percent, respectively. The comparison between weak and strong acids
found that strong acids increased the SCOD/TCOD more than weak acids by up to 7 percent.
Finally, considering the biochemical methane potential (BMP), the results showed that pretreatment
at 121 c without acid supplementation for 30 minutes demonstrated the highest BMP, which was
14 percent higher than that of the untreated cassava decanter cake.