Leachate treatment using supercritical water

Abstract

AbstractThis work reports new experimental data for the oxidation degradation of landfill leachate using supercritical water treatment (ScWO) without addition of any oxidants. The treatment reduced significantly the original concentration of pollutant compounds in the liquid waste. The parameters used to evaluate the efficiency of the treatment (and leachate degradation) were chemical oxygen demand (COD), total organic carbon (TOC), turbidity, colour, and absorbance. The experiments were conducted using a continuous flow reactor built in Inconel 625. The degradation oxidation reactions were carried out using temperature between 350 and 600 °C (for COD intial concentrations of 1580 mg · L−1) and between 450 and 700 °C (for COD intial concentrations of 2000 mg · L−1), pressures of 15 and 22.5 MPa, feed streams of 6 and 12 g · min−1, and reaction operation time of 40 min. Increasing pressure improved degradation of organic pollutant compounds, whereas the increase of the feed flow rate did not show any positive effect on the performance of the treatment. However, the most important factor on the degradation of leachate was temperature; increasing temperature from 350 to 600 °C reduced COD level in 31.3 and 34.4 % for 15 and 22.5 MPa, respectively. Hydrogen was the gas produced in the highest amount for all the experimental conditions studied. The results suggested that supercritical water is a promising technique to treat leachate and consequently reduce its pollutant capacity. Thus, the data presented here can be used as a basis for future studies.