Abstract:
To study the treatment of 5,000 mg/l of palm-oily wastewater containing with anionic surfactant (Sodium Dodecyl Sulphate, SDS) by Electrostatic Coalescer process. Various factors, like types and height of coalescing beds, liquid flow rate, type and distance of electrodes, applied voltage and addition of electrolyte were analyzed in both batch and continuous processes. The result has shown that the highest COD removal efficiency was obtained by using polyester bed (aquarium fiber) 3.5 cm height and 5 L/hr as continuous liquid flow rate. It is possible to apply the electro-coagulation/flotation instead of chemical addition at the bottom of coalescer column for enhancing the overall treatment efficiencies. Moreover, the highest efficiencies can be obtained with the 3 cm of aluminum electrodes located at top of coalescer column, especially at lowest voltage applied: this corresponds with electrocoalescense mechanism increasing the oil droplet size in concentrated liquid phase. Negative effect of electrolyte addition was observed in this work, whereas the treatment efficiencies can be enhanced for the 50% liquid recirculation into reactor with 1 L/hr and 3V in voltage: the treatment efficiencies and oil layer thickness can be increased about 15% (50-65% to 60-70%) and 25% (2.4 to 3.2 cm) respectively. Finally, in future, the electrostatic coalescer process should be possibly applied for not only treating the stabilized oily wastewater but also recovering the oil phase.