Removal of ions from leachate by using membrane capacitive deionization

Leachate, an important environmental problem resulted from landfills, causes a potential threat for groundwater and surface water. The biological processes are not effective to treat especially old landfill leachate due to content of refractory organic constituents, ammonia, heavy metals, chlorinated organics and inorganic salts. In this thesis, removal of various ions from leachate using a membrane capacitive deionization (MCDI) system was investigated at lab scale. Up to now, the studies carried out using MCDI system have generally focused on removing several ions from groundwater, domestic and industrial wastewaters. The experiments were carried out at voltages in the range of 0.5 – 5.0 V and contact times in the range 15 – 120 minutes. Maximum removal of phosphate from leachate was obtained to be 77% at voltage of 4.0 V and contact time of 15 min. In the range of 3.0 – 4.0 V, CI, NO3- and NO2- ions were completely removed from leachate at lowest contact time of 15 min. The ions removal of SO4-2 and Na+ were higher than 80 % at contact time of 15 min in the range of 3.0 - 5.0 V. Maximum removal for NH4+ ion was found to be 90 % at contact time of 120 minutes under a voltage value of 3.5 V. K+ ion was removed 37 % at 2.5 V, the removal reached to 90 % when the voltage was increased to 3.5 V. Maximum removal for Ca+2 ion was higher than 70 % under voltages in the range of 3.0 – 4.0 V.