Research on treatability of landfill leachates by hydrogen peroxide in the existence of ferric ions

In this study, the oxidation of organics resisting to biological decomposition process in leachates by means of hydrogen peroxide in the existence of ferrous ions in the medium (Fenton's Reactions) was investigated experimentally. It is illustrated that some amount of non-biodegradable organic substances in leachate can be treated by Fenton reactions. In the experiments, raw leachate from İstanbul-Şile-Kömürcüoda solid waste sanitary landfill and its anaerobic and anaerobic + aerobic treated effluents were used. Optimum experimental conditions for parameters such as pH, Fe2+ and H2O2 doses in order to understand the process performance were determined by realisation of COD, BOD, colour and turbidity analysis in the supernatants of all of the samples. Fenton's processes can occur at lower pH values like 3. After termination of the reactions, in order to precipitate ferrous and ferric ions in the liquid medium, pH value was brought in about 8.5-9.0. At the end of all experimental runs, COD removals from diluted effluent of anaerobic treatment and anaerobic + aerobic treatment effluent were almost 75%. Those from anaerobic treatment effluent and raw leachate sample were obtained as 65% and 59% respectively. As an interesting result, it is observed that about 30 % of COD remaining after Fenton's Reactions was biodegradable. During all the runs, removal of colour and turbidity were at the levels of 99-100%. Measured sludge volumes (as sludge volume /total volume) were 1/5-1/15 that are changing depending on sample's initial COD concentration and applied Fe2+ dose.