Electrocoagulation of a chocolate industry wastewater in a Downflow column electrochemical reactor

Abstract

Electrocoagulation is a process that consists in the production of coagulant species by the dissolution of a sacrificial anode. This work presents by the first time the performance of a Downflow Column Electrochemical Reactor (DCER) to conduct an electrocoagulation process to remove organic and inorganic matter from wastewater (6 L) of a chocolate industry. A deep flow battery connected to a solar panel was used to energize the aluminium electrodes. The studied variables were electrical current (I: 1.58 A and 3.16 A) and liquid volumetric flowrate (QL: 0.032 L/s and 0.060 L/s). The response variables were COD and color removal (%). It was concluded that during the first 5 min, the interaction of both variables exerts the most significant effect on COD removal, while for the rest of the treatment the effect of I is more statistically significant than QL. Regarding color, an 80 % was removed during the first 5 min of treatment. It was also concluded that I = 3.16 A and QL = 0.06 L/s were the conditions to reach the maximum COD and color removal, 63 and 97 %, respectively. In addition, the hydrogen production was theoretically estimated to be 0.26 L after 20 min of treatment. A cost analysis was conducted by taking into account the sludge management, electrode consumption, electricity consumption by electrodes and pump. The calculated cost was 4.01 USD/m3. A second order adsorption model was found to provide an excellent fitting of the experimental COD and color data.