Supercritical Water Oxidation in a Pilot Plant of Nitrogenous Compounds: 2-Propanol Mixtures in the Temperature Range 500−750 °C

Abstract

Supercritical water oxidation (SCWO) has been shown to be an effective method for the treatment of industrial wastes. Organic compounds containing nitrogen are very usual in industrial wastes, and therefore, it is necessary to study the oxidation behavior of such compounds in order to improve the applicability of this technology to wastewaters and sludges. In this paper, oxidation parameters of several nitrogen-containing compounds in supercritical water such as aniline, acetonitrile, pyridine, and the intermediate stable compound ammonia are studied, using 2-propanol as auxiliary fuel. SCWO of feedstreams containing 2-propanol and the nitrogenous compound was carried out using a pilot-plant scale, based on a continuous-flow reactor system. Results show that for these compounds suitable conditions for SCWO are the following: reaction temperature in the range 600−700 °C; stoichiometric amount of oxygen at residence time of 40 s. In these conditions, compound concentration in the effluent is below detection limits, TOC removal is greater than 99.97%, and N removal is greater than 97%.