Treatment of Biodiesel Wastewater by Electrocoagulation Process
Anchalee Srirangsana, Maneerat Ongwandeeb and Orathai Chavalparita
a Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand.
b Faculty of Engineering, Mahasarakham University, Mahasarakham 44150, Thailand.
Received 20 November 2008; Accepted 19 January 2009
Abstract
The objective of this research was to determine the optimum conditions for biodiesel wastewater treatment using an electrocoagulation process. Wastewater samples were obtained from a small-scale, commercial biodiesel production plant that employs an alkali-catalyzed tranesterification process. The wastewater was characterized by the high contents of alkali and high oil content of 6,020 mg/L. Tested operational conditions included types of electrode, current density, retention time and initial pH. The tested electrode materials for electrocoagulation were aluminum (Al), iron (Fe) and graphite (C). Five tested pairs of anode and cathode materials included Fe-Fe, Fe-C, Al-Al, Al-C, C-C. Results show that the optimum conditions were achieved by using the electrodes of Al-C, applying the current density of 8.32 mA/cm2 to the wastewater with an initial pH value of 6 for 25 min. The removal efficiency was found to be 97.8 % for grease & oil (G&O), 96.9 % for SS and 55.4 % for COD. Moreover, the small amount of produced sludge was readily to remove from the treated wastewater.
Keywords: biodiesel wastewater; electrocoagulation; grease & oil removal; electrode materials
* corresponding author : Dr. Orathai Chavalparit