Resource utilization of landfill leachate gasification in supercritical water

In this paper, original landfill leachate gasification in supercritical water was studied in high heating rate batch reactor. The experiments were carried out in the temperature range of 500-650 degrees C, residence time range of 0-30 min, and pressure range of 22.5-26.0 MPa. The effects of temperature, pressure, residence time, catalysts and oxidant on gasification, chemical oxygen demand (COD) and NH3-N removal rate were examined. As a result, high heating rate could promote landfill leachate gasification in supercritical water better. High temperature and long residence time could improve gasification efficiency. The highest carbon gasification efficiency (CE) reached 99.2% and hydrogen yield reached 26 mol/kg with KOH at 650 degrees C, 30 min. KOH could also improve COD and NH3-N conversion significantly. The highest COD and NH3-N removal rate was 94.6% and 51.0%, respectively. The addition of oxidant had the same effect on NH3-N elimination obtained with KOH. The results of experiments might predicate that the combination of catalytic and partial oxidation might be an effective method to remove NH3-N for landfill leachate gasification in supercritical water.