Effect of Calcined Limestone on the Performance of Roughing Filter for Turbidity Removal of Palm Oil Mill Effluent

Abstract

Malaysia is considered as a major palm oil producer in the world. Therefore, it is vital to utilize an environmentally friendly and inexpensive method to treat palm oil mill effluent (POME) in Malaysia. Nowadays, the use of natural absorbent to remove pollutants from POME has gained remarkable attention. The main objective of this research was to investigate the effect of calcinated limestone on turbidity removal and analyze the removal rate of pollution of POME. A column studies was conducted using different particle size of limestone (4, 12, and 20 mm), raw and calcinated at 800°C and 600°C at filtration rates of 20, 60, and 100 mL/min. An experimental model was conducted using central composite design (CCD) in response surface methodology (RSM). According to analysis of 3D surface respondents, the first optimum condition was at 800°C with 2 h of calcination time, flow rate of 20 mL/min, and limestone size of 4 mm. The second optimum condition was calcinated limestone at 600°C using a lower flow rate and smaller size of calcined limestone (CLS). The first and the second optimum conditions achieved turbidity removal of 68% and 62%, respectively, both of which outperform raw limestone with removal rate of 55%. Equilibrium isotherms in this study were evaluated using the Langmuir and Freundlich isotherms. The results showed that adsorption isotherm data is more fit to the Langmuir isotherm, with 0.95 R2 compared with 0.85 R2 for the Freundlich isotherm at 800°C.