Optimization of adsorption-coagulation process for treatment of palm oil mill effluent (POME) using alternative coagulant

Abstract

Activated carbon has been using as an adsorbent for wastewater treatment for decades. It has also been reported that use of fly ash to adsorb impurities in waste water treatment .The main objective of this study is to optimize hybrid adsorption-coagulation method for removal of color and other impurities presence in palm oil mill effluent (POME).Mango pit is a natural environmental friendly coagulant and have many advantages over commercially available aluminum and ferric salts used for water and wastewater treatment. On the other hand fly ash can be distinguished from other adsorbent in the way it desorbed and re used for the same purpose. This study further investigates the combination of fly ash with mango pit as coagulant agent for removal of color and other effluent quality parameters as TSS, TDS, COD and BOD. Palm oil mill wastewater after aeration process was collected and characterized in order to determine input conditions. Two sets of experiments were performed using jar test method namely; only adsorption using fly ash and the second is using fly ash in combination with mango pit in hybrid adsorption-coagulation system. In the first set of experiments only adsorption process studied using fly ash as an adsorbent by varying parameters affecting the process. Samples of 300ml wastewater were used with variable fly ash particle size ranging from 355pm and 500pm and operated at 200rpm. Results showed that with decrease in particle size the amount of pollutant adsorbed increased and the amount of BOD5, color, TDS, COD and TSS adsorbed increased as the weight of the boiler fly ash used was increased, therefore process was optimized using 355 pm granule size and 90g of dose which gave results in color reduction up to 91%, COD 82%, BOD5 83%, TDS 74%, TSS 78% and turbidity 93% respectively. Further in the second set of experiments equal amount of wastewater samples were investigated using hybrid adsorption-coagulation method by varying concentration of adsorbent-coagulant as (50g-0.6ml, 70g-0.8ml, 90g-1.2ml). Finally both results obtained from first and second sets of experiments were compared at optimum point, an improved trend was recorded when hybrid system was applied towards the reduction in Color from 91% to 97%, COD from 82% to 89%, BOD from 83% to 94%, TDS from 84% to 93% and TSS from 88% to 96% respectively. Hybrid coagulation-Adsorption method has not only positive impact on reduction of water quality parameters but also very cost effective and environmental friendly process. Both ingredients used in this process be obtained easily; other advantages include low sludge production and the less amount of coagulants used.