Abstract

The palm oil industry has been identified as one of the main contributors of organic pollution. These industries generate large volumes of effluent and solid waste including boiler fly ash. The kinetics and intraparticle diffusivities of BOD, TSS and colour reduction from palm oil mill effluent (POME) using boiler fly ash was reported in this paper. The amount of BOD, colour and TSS adsorbed increased as the weight of the boiler fly ash was increased. Also, the smaller adsorbent particle size of 425 mm adsorbed more than the 850 mm size. Attempts were made to fit the experimental data with the pseudo - first order and pseudo-second order kinetic equations. The pseudo - second order model gave a better fit to the sorption process. The rate constants obtained for the pseudo-second order model are 2.26 x 10^-5 mg/g-min for BOD, 6.48 x 10^-4 mg/g-min for colour and 9.55 x 10^-4 mg/g-min for TSS at 30°C. The mechanism of sorption was investigated by using the intraparticle diffusion model. The regression coefficient for the intraparticle diffusion model showed that BOD with a value of 0.9744 was well correlated than TSS (R² = 0.1018) and colour (R² = 0.1450). This means that BOD adsorption was particle diffusion controlled while colour and TSS were film diffusion controlled. Therefore, this study reveals that boiler fly ash can effectively be used as an adsorbent for POME treatment and also established the kinetic and mechanisms of the sorption process. Also, the results of this study could serve as effective design parameters for a treatment plant to further reduce BOD, colour and TSS from POME.

Key words: Adsorption, boiler fly ash, kinetics, pome, wastewater.