Statistical analysis of optimum Fenton oxidation conditions for landfill leachate treatment

Abstract: Optimal operating conditions observed by peer reviewed publications for Fenton oxidation of raw and biological and coagulation treated leachates were reviewed and statistically analyzed. For the first-stage Fenton oxidation, the optimal pH range of 2.5–4.5 was observed for raw and coagulation treated leachates with a median pH of 3.0, whereas, for biologically treated leachate the optimum pH range was 2.5–6.0 with a median pH of 4.2. Theoretically, the optimal ratio of H2O2/Fe2+ should be the ratio of rate constants of the reactions between OH radical with Fe2+ and H2O2, which is approximately 11; however, for leachate treatment, a median optimum relative dose of 1.8 (w/w) (3.0M/M) was observed. Biologically treated leachate showed relatively lower optimum ratio of H2O2/Fe2+ doses (median: 0.9 w/w) as compared to raw (median: 2.4 w/w) and coagulation treated (median: 2.8 w/w) leachate. Median absolute doses of H2O2 and Fe2+ were 1.2mg H2O2/mg of initial COD (COD0) and 0.9mg Fe2+/mg COD0, respectively and raw leachate required higher reagent doses compared to pretreated leachates. A universal Fenton oxidation relationship between COD removal efficiency (η) and COD loading factor (LCOD ) for landfill leachate treatment was developed. As LCOD increases from 0.03 to 72.0, η varies linearly as This robust linear relationship between LCOD and η holds for Fenton oxidation of raw as well as biological and coagulation treated leachates. The relationship was validated using Leave-one-out cross validation technique and errors in predicting η using LCOD were evaluated by applying Monte Carlo Simulation. As a result, the relationship can be used as a universal equation to predict Fenton treatment efficiency for a given COD0 loading in the range of 0.03–72.0 for landfill leachate treatment. [Copyright &y& Elsevier]