Sequential Treatment of Landfill Leachate By Advanced Oxidation Processes and Struvite Precipitation

Abstract

Landfill leachate contains organic, inorganic compounds, heavy metals, ammonia, and xenobiotic compounds which are considered unsafe for discharging into surface water which requires to be treated before its discharge into the water. In this paper, preliminary studies are reported on the application of Fenton, Struvite, and Electrooxidation processes for the removal of Chemical Oxygen Demand (COD) and ammonia from landfill leachate. Various operational parameters like pH, dosage, reaction time, and applied voltage were optimized in laboratory batch experiments and evaluated for removal of COD and ammonia. Results demonstrated that the Fenton process could effectively remove COD and ammonia by 75% and 23% respectively at 210 min for Fe+2:H2O2: 1:5 at a fixed pH 3. The Struvite process has been effective in the removal of ammonia by 74% at pH 9 with the dosage of Mg+2:PO43-:NH4+ at 1:1:1 ratio. Results from Electrooxidation for COD and ammonia were observed as 58.25% and 44% respectively at the applied voltage 8 V for a reaction time of 60 min. The efficiency of treatment processes was also evaluated in Sequential processes for COD and ammonia i.e., Sequence-I (Fenton-Electrooxidation-Struvite) and Sequence-II (Fenton-Struvite) at pre-optimized conditions. The sequential processes have been depicted, the removal efficiencies of COD and ammonia of 89% and 82% by Sequence-I; 76.77%, and 77% by Sequence-II respectively. The present study demonstrates that Fenton followed by Electrooxidation and Struvite is an effective treatment process that can enhance the treatment of landfill leachate.