Electrochemical Treatability of Refractory Pollutants in Landfill Leachate

Photoelectrochemical treatment of landfill leachate in a continuous flow reactor

“…Hypochlorite generated is a strong oxidant that can oxidize aqueous organic compounds. Chiang et al (1995b) found that COD and ammonium removal efficiencies in electrooxidation of leachate increased with the current density. However, in a direct electrochemical oxidation, pollutant removal efficiency at the same charge loading (in coulomb per litre) is independent of current density.…”

“…In PEC process, COD reduction efficiency ranges from 70% to above 90%, and ammonium removal efficiency almost reaches 100% under appropriate conditions. Chiang et al (1995b) found that removal of ammonium was obviously dominant when in competition with removal of COD under indirect oxidation during electro-oxidation of an old leachate. Cossu et al (1998) reported that the removal rate of ammonium was lower than that of COD at the initial stage of electro-oxidation of an old leachate when direct oxidation predominated, and then ammonium was substantially removed in the subsequent electro-oxidation stage when indirect oxidation became prevalent.…”

“…A possible explanation is that an increased current density during electro-oxidation enhanced chlorine generation, which was probably responsible for subsequent removal of ammonium. Chiang et al (1995b) reported that during electro-oxidation of leachate with the current density of 25.00 mA/cm 2 , COD removal efficiency was about 50% higher than that by electro-oxidation with 6.25 mA/cm 2 . In our case the Cl À concentration was high as 4500 mg/L.…”

Ammonium removal from landfill leachate by anodic oxidation

“…In the case of landfill leachate, electrochemical degradation techniques using different types of anodes, i.e. TiO 2 /RuO 2 [11,12], PbO 2 /SnO 2 [14], Ti/Pt [15], SPR [16], and PbO 2 /Ti [17], have also proved to be capable of removing the ammonium loading. In these studies the initial concentration of N-NH 4 + ranged from 380 mg L −1 to 3000 mg L −1 and applied current densities ranged from 15 mA cm −2 [17], to 130 mA cm −2 [15].…”

“…Hence, high ammonium removal efficiency is expected. Other anodic materials allowed high ammonium removal efficiencies; however, they were not so effective in the reduction of COD [11][12][13][14][15][16][17]. The aim of this study is to analyse the influence of the operation variables such as current density, chloride concentration and initial ammonium concentration on the electrooxidation of the ammonium contained in landfill leachates using a BDD anode.…”