Hybrid Process Combining Electrocoagulation, Electroreduction, and Ozonation Processes for the Treatment of Grey Wastewater in Batch Mode

Abstract

The present study investigates the electrocoagulation-electroreduction (EC-ER) and ozonation process (ECRO process) for the treatment of grey wastewater (GWW) loaded with organic and inorganic matter, oil and greases (O&G), and total suspensions solids (TSS). Several factors, such as electrode materials, current density, electrolysis time, initial pH, wastewater conductivity, and ozone dosage were investigated. High treatment efficiency of GWW was recorded while applying the EC-ER technique followed by the ozonation process. The best performance for GWW treatment by the EC-ER process was obtained using aluminum and graphite electrodes operated at current density of 0.9 A/dm2, during 90 min of electrolysis time and at pH around 10 whereas the ozonation treatment of GWW was found to be more effective at pH 8 and at 9.2 g/h of ozone dosage. Under these optimal conditions, combining the electrochemical (EC-ER) and ozonation processes enhanced the removal of organic and inorganic contaminants from GWW. The ECRO process reduced total chemical oxygen demand (CODT) by 91.31±1.09%, total organic carbon (TOC) by 84.59±1.71%, soluble chemical oxygen demand (CODs) by 90.17±0.26%, and dissolved organic carbon (DOC) by 82.11±2.19%. Besides, the removal efficiency of biological organic demand (BOD), O&G, and total phosphorous (PT) reached 92.61±0.24%, 90.40±0.31%, and 86.66±0.00%, respectively.