Residual oil and suspended solid removal using natural adsorbents chitosan, bentonite and activated carbon: A comparative study

Abstract

Palm oil mill effluent (POME), which contains about 4000 mg/l of residual oil, has been chosen to remove its residual oil using three types of adsorbents. Jar-test method has been used to identify the best adsorbent to remove the residual oil from POME. Chitosan was compared to activated carbon and bentonite as a potential residual oil remover. Chitosan showed the best removal compared to the other adsorbents for all the parameters studied. Chitosan could successfully remove 99% of residual oil and minimize the suspended solid content to a value of 25 mg/l from POME at a dosage of 0.5 g and employing a mixing time of 30 min, a mixing rate of 100 rpm, sedimentation for 30 min and a pH value of ranging from 4.0 to 5.0. For activated carbon and bentonite, the optimum dosages were 8.0 g and 10.0 g/l, respectively, 30 min of mixing time at 150 rpm, 80 and 60 min of settling time, respectively, and pH of 4.0–5.0 to obtain the same percentage of removal as performed by chitosan. Activated carbon and bentonite can only reduce the suspended solid values up to 35 and 70 mg/l, respectively, at the optimized conditions.