Combined EC/EO processes for treating goat cheese whey wastewater

Abstract

The dairy industry is currently one of the most important industrial sectors in the world, and due to the high demand for products, is considered the largest source of industrial wastewater in the food sector. Whey wastewater is the most abundant liquid by-product and is characterized by a high concentration of organic load. Thus, the treatment of cheese whey wastewater before discharge is considered important. Therefore, the processes of electrocoagulation (EC), electrooxidation (EO), as well as their combination (EC/EO) have been purposefully used for the treatment of goat cheese wastewater. The main parameters (current density (mA/cm2), agitation (rpm), pH, and operating time (min)) affecting the removal efficiency of chemical oxygen demand (COD) were studied for each process. Whey effluent was treated under the optimal conditions of EC with aluminum electrodes, and EO with a boron-doped diamond electrode (BDD), removing 40.5% and 55.3% of COD, respectively. The combined use of EC/EO eliminated 82.4% of COD in a total time of 90 min. Total nitrogen (TN), chloride (Cl−), nitrate (NO3−), and phosphate (PO4−3) pollutants were also determined. The aroma profile of the raw substrate changed during the electrochemical processes. The determination of the volatile organic compounds (VOCs) in raw and treated (EC, EO, and EC/EO) goat whey wastewater was monitored using a thermal desorption unit followed by gas chromatography/mass spectrometry (TD-GC/MS) after extraction of VOCs using the HiSorb technique. Coupling electrochemical technologies increased odor emissions from goat cheese whey wastewater.