Optimization of multiple parameters for treatment of coking wastewater using Fenton oxidation

Present study deals with the treatment of coking wastewater (CWW) using Fenton oxidation process for the degradation of pollutants containing chemical oxygen demand (COD), phenol and cyanide. The experiments were performed in batch mode to study the effect of operating parameters like initial pH (pH_i), temperature (T), oxidant H₂O₂ amount, catalyst mass loading (Cw) and treatment time (t_R). The response surface methodology (RSM) gave optimum value of pH, H₂O₂, Cw and t_R as 3, 0.3 M, 1.85 g/L (0.0266 M) and 1.52 h. At this optimum operating condition maximum 84.66% COD, 88.46% phenol and 79.34% cyanide reduction were achieved from initial value of COD (COD_i) = 2810.0 mg/L, phenol_i = 283.0 mg/L and cyanide_i = 18.88 mg/L. Results reflect that Fenton oxidation is an effective process for the reduction of pollutants present in CWW. The CWW treated by Fenton oxidation having average value COD = 590.0 mg/L, phenol = 39.49 mg/L and cyanide = 5.2 mg/L was further treated by adsorption process as second stage treatment, and these values were reached to COD = 199.0 mg/L, phenol = 0.0 mg/L and cyanide = 2.36 mg/L. The response surface methodology (RSM) was used for the designing and optimization of the experiments. Analysis of variance (ANOVA) suggested the high regression coefficient R² = 0.999 and 0.993 for COD and phenol removal respectively. The two stage treated CWW can be recycled and reused in same industry for various purpose.