Homogeneous vs. Heterogeneous Photo-Fenton Processes in the Treatment of Winery Wastewater

The winery industry generates large volumes of wastewater which can be toxic if released to the environment without proper treatment. The aim of this work was to treat two winery wastewaters (from red and white wine production) using Fenton-based processes. With the application of the best operational conditions, namely, pH = 3.0, [ferrocene] = [FeSO₄•7H₂O] = 0.50 g/L, [H₂O₂] = 155 mM, temperature = 298 K, and radiation UV (254 nm), to the treatment of a red WW, a chemical oxygen demand (COD) removal of 98.9 and 84.5% for the homogeneous and heterogeneous photo-Fenton processes, respectively, was achieved. The same conditions were applied in the treatment of a white WW and a 98.9 and 84.5% COD removal was achieved. Based on the results, it can be deduced that homogeneous and heterogeneous Fenton-based processes are effective in organic carbon removal, UV-C radiation is essential in hydroxyl radical (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi>HO</mi></mrow><mrow><mtext>•</mtext></mrow></msup></mrow></semantics></math></inline-formula>) generation, and the multiple addition of H₂O₂ reduces <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mrow><mi>HO</mi></mrow><mrow><mtext>•</mtext></mrow></msup></mrow></semantics></math></inline-formula> scavenging. Finally, it is concluded that both the homogeneous and heterogeneous photo-Fenton processes are effective for red and white WW treatment.