Environmental Engineering and Management Journal December 2014, Vol.13, No. 12, 3153-3160 http://omicron.ch.tuiasi.ro/EEMJ/ “Gheorghe Asachi” Technical University of Iasi, Romania COD REDUCTION OF BAKER'S YEAST WASTEWATER USING BATCH ELECTROCOAGULATION Mohammad Al-Shannag 1 , Zakaria Al-Qodah 2 , Kholoud Alananbeh 3 , Nahla Bouqellah 3 , Eman Assirey 4 , Khalid Bani-Melhem 5 1 The University of Jordan, Faculty of Engineering and Technology, Chemical Engineering Department, 11942 Amman, Jordan 2 Taibah University, Department of Chemical Engineering, P.O. Box 344 Madinah, KSA; Permanent address: Al-Balqa Applied University, Department of Chemical Engineerin, Amman, Jordan 3 Taibah University, Department of Biology, Madinah, KSA 4 Taibah University, Department of Chemistry, Madinah, KSA 5 Hashemite University, Faculty of Natural Resources and Environment, Department of Water Management and Environment, Al-Zarqa, Jordan Abstract The aim of the present work was to investigate experimentally the reduction of Chemical Oxygen Demand (COD) levels from baker’s yeast wastewater (BYW) using batch electrocoagulation (EC) treatment process. An electrocoagulation unit with six iron electrodes was designed to achieve this treatment task. The effect of several operational parameters including pH, direct current (DC) density (I ρ ), mixing speed (MS), and temperature (T) on the performance of EC process was studied. The results indicated that the maximum removal efficiency of the COD was up to 85%. The visual test showed that the electrocoagulation process was able to remove completely the dark brown color of baker’s yeast wastewater. The corresponding electrical energy and electrode consumption per kg COD removed was around 0.493 kWh and 2.956 kg iron, respectively. In addition, it was demonstrated that the reduction rate of COD follows the first-order model whose kinetic parameter, k, depends strongly on the DC current density according to a power law relation. Key words: Baker’s yeast wastewater, COD kinetics, electrocoagulation, iron electrodes, wastewater treatment Received: July, 2014; Revised final: September, 2014; Accepted: September, 2014  Author to whom all correspondence should be addressed: zqudah@taibahu.edu.sa ; z_alqodah@hotmail.com 1. Introduction Food and fermentation industries usually generate highly polluted wastewater containing high level of different organic pollutants, quantified as Chemical Oxygen Demand (COD), including biodegradable organic pollutants expressed as Biochemical Oxygen Demand (BOD), and sulfates (Zub et al., 2008). In particular, the production of baker's yeast from molasses fermentation processes generates high amounts of wastewater. The resulted baker’s yeast wastewater (BYW) is characterized by high COD and BOD values that reach 100 and 50 g/L, respectively (Liang et al., 2009). The baker’s yeast wastewater is strongly nitrogenous with total nitrogen content of 1.5 g/L, while sulfate content could reach 10 g/L (Kalyuzhnyi et al., 2005). Moreover, BYW is acidic (pH from 4 to 5), has a strong odor, and a dark brown color (Gengec et al., 2012). The dark brown color is attributed to the