The removal of COD from refinery wastewater by Fenton reagent

Chemical oxygen demand (COD) has been the crucially problematic parameters in refinery wastewater treatment. This study was conducted to investigate COD removal in refinery wastewater with Fenton process. The effects of pH value, H₂O₂ dosage, the mole ratio of Fe²⁺ to H₂O₂, oxidation time and oxidation temperature on COD removal were discussed. The results showed that COD removal efficiency first increased then decreased with the increase of solution pH, and the highest COD removal appeared as pH was about 2.5 to 3.0. The COD removal rose from 36.61 % to 43.44 % with H₂O₂ concentration from 25 mmol-L1 to 60 mmol-L"1. The COD removal first increased then decreased with the mole ratio of Fe²⁺ to H₂O₂. The maximum COD removal appeared as the mole ratio of Fe to H₂O₂ is 1:5. The COD removal increased with time and leveled off after 120 minutes. When the oxidation temperature increased from 30°C to 50°C, the COD removal increased slightly from 40.98% to 44.81%.