A comparative study of UV–Fenton, UV–H ₂ O ₂ and Fenton reaction treatment of landfill leachate

In this study, laboratory experiments were conducted to compare the efficacy of several H2O2-based advanced oxidation processes (AOPs): UV-Fenton, UV-H2O2, and Fenton reagent, to treat landfill leachate with the objective of removing COD and improving the leachate's overall biodegradability (evaluated in terms of BOD5/COD ratio). The results indicated that, at optimized experimental conditions of 25 degrees C, pH 4.0, 4000 mg L(-1) H2O2, 30 mg L(-1) Fe(II) (for UV-Fenton and Fenton) and 60 min reaction time, the UV-Fenton system showed the highest COD removal. The COD removal rate in the H2O2-based AOPs was strongly dependent on the concentration of H2O2 and the pH value. Temperature had little effect on overall COD removal rate in the Fenton and Fenton-like systems. All three systems would result in a significant increase in the ratio of BOD5/COD, from 0.17 to about 0.60, at the applied H2O2 dosage of 4000 mg L(-1). The increase in biodegradability of the AOP leachate indicates that these AOPs would be beneficial for the subsequent biological treatment process. The UV-Fenton process was found to be the most effective approach of these H2O2-based AOPs to enhance the biodegradability and eliminate the colour of the leachate.