Influence of Elevated Temperature and Pressure on Treatment of Landfill Leachate by Potassium Ferrate(VI)

Abstract

AbstractThe significant problem is the treatment of landfill leachate characterized by high chemical oxygen demand (COD) and total organic carbon (TOC) and presence of biodegradation inhibitors such as heavy metals and oily substances. For the case of landfill leachate (pH 7.9, color 1550 mg Pt/L, COD 1880 mg O2/L, TOC 620 mg/L, total nitrogen (TN) 220 mg/L, total phosphorus (TP) 6 mg/L and heavy metals), the effect of elevated pressure and temperature on the decrease COD value by potassium ferrate(VI) (K2FeO4) was investigated. Taguchi method (TM) was employed for optimizing the treatment process parameters (repetition, pH, K2FeO4 concentration, time, temperature, and pressure). Maximizing the criterion function of signal-to-noise (S/N), the optimal parameters were determined: pH 3.5, K2FeO4 2.0 g/L, time 45 min, temperature 30 °C, and pressure of 1 MPa. At optimal conditions, a decrease of color, COD, TOC, and TP was above 91%. Additionally, the decrease of TN was 48.2%. Comparatively, at atmospheric pressure (0.1013 MPa) and at 19 °C, the decrease of color, COD, TOC, TP, and TN was 99.9%, 83.0%, 79.0%, 19.1%, and 100%, respectively. Addition of potassium ferrate(VI) may improve organic compound removal and decreases energy consumption in subcritical water oxidation. Graphical abstract