Electrochemical treatment of tannery wastewater—Raw, coagulated, and pretreated by AOPs

ABSTRACT

This study on tannery wastewater treatment showed that indirect electrooxidation by chlorine generated at a Ti/SnO₂/PdO₂/RuO₂ (SPR) anode led to full ammonia removal, and a decrease in chemical oxygen demand (COD) of up to 77.0%. A combined process of coagulation + H₂O₂/UV + electrooxidation allowed us to achieve a decrease in COD of up to 97.5%. Equations describing the kinetics of the decrease in COD, the relationship between the decrease in COD and current, and the relationship between the current efficiency of COD reduction and the initial concentrations of the reagents were established. The changes in the Adsorbable Organically Bound Halogen (AOX) value were determined, and the individual compounds, including chloroorganics, present in raw and treated wastewater were identified by gas chromatography mass spectrometry (GC-MS). Values of AOX increased in the initial phase of electrooxidation, while afterwards they decreased.

KEYWORDS:

• Chemical oxidation
• coagulation
• electrochemical oxidation
• tannery wastewater