Municipal Solid Waste Leachates Destruction and Metals Recovery by Supercritical Water Oxidation

ABSTRACT

Municipal solid waste leachate dissolved with nitrates of Cr, Pb, and Cu was investigated using a supercritical water oxidation process in this study. The destruction efficiency of chemical oxygen demand increased with the higher temperature and longer reaction time. A first-order expression applied for chemical oxygen demand was determined with a pre-exponential factor of 318 s^–1 and activation energy of 58 kJ/mol. Recovery efficiency of Cr, Pb, and Cu from initial solution into solid product increased with the higher temperature and longer reaction time. X-ray diffraction of solid products showed that the metal species were found to be Cu₂O, HCrO₂, and CaCO₃ at temperature 400°C, while the structure were identified as CuO, Cr₂O₃, PbCrO₄, and CaCO₃ at temperature 500°C.

KEYWORDS:

• chemical oxygen demand
• degradation kinetics
• leachate
• metal recovery
• supercritical water oxidation

Additional information

Funding

This project is supported by the National Basic Research Program of China (973 Program, No. 2011CB201506) and National Natural Science Foundation of China (No. 51276168).