The treatment of landfill leachate over Ni/Al2O3 by supercritical water oxidation

•The experiments showed that Ni/Al2O3 as catalyst improved the treatment efficiency of landfill leachate.•The treatment efficiency increased with increasing temperature and reaction time.•Hydrogen peroxide was used as the oxygen source and excess O2 increased the treatment efficiency of landfill leachate, however, a part of excess O2 used was discarded from the reactor unless reacted in the gaseous stream.•During the catalytic SCWO of the landfill leachate over Ni/Al2O3, the nitrogen content was removed partly.

This study presents the findings of our research regarding the catalytic treatment of landfill leachate over Ni/Al2O3 by supercritical water oxidation. Hydrogen peroxide was used as the oxygen source. The experiments were carried out at a constant pressure of 25 MPa, in the temperature range of 400–600 °C and the reaction time range of 30–150 s. The effects of temperature, reaction time, pressure, catalyst and oxidant use on the total organic carbon and total nitrogen contents of the liquid effluents were examined. As a result, it was seen that supercritical water oxidation was a very effective method for the treatment of landfill leachate. Treatment efficiencies up to 98.2% in terms of total organic carbon conversion were obtained. However nitrogen removal achieved about 57% in terms of total nitrogen conversion.

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