The Effect of H2O2 Interference in Chemical Oxygen Demand Removal During Advanced Oxidation Processes

Hydrogen peroxide (H2O2) is one of the most oxidants in AOPs. By H2O2 dissociation, hydroxyl radical with a standard oxidation potential of 2.7 is produced. It is reported H2O¬ residual in AOPs has been led to interference in chemical oxygen demand (COD) test and it is able to hinder biological treatment of waste water. Because of high mixed organic load of solid waste leachate, this study investigated effect of H2O2 interference in COD removal from solid waste leachate.
In this study effect of parameters such as pH (3,5,7,12), H2O2 dose (0.01, 0.02, 0.03, 0.04 mol l-1), and time reaction(10,20,30,40,50,60 min) evaluated on H2O2 interference in COD removal from solid waste leachate.
Optimum pH and concentration were 3 and 0.02 moll-1 respectively. With increasing reaction time, COD removal was increased. The false COD obtained between 0.49mg per 1mg of H2O2. The average of COD removal by H2O2 for 60 min was 6.57%. Also reaction rate of this process was 0.0029 min-1.
The presence of H2O2 leads to overestimation of COD values after reaction time because it consumes the oxidation agent. The extent of H2O2 interference in COD analysis was proportional to the remaining H2O2 concentration at the moment of sampling.