Development of Wastewater Treatment Technique by Catalytic Oxidation in Superheated Steam

Atsushi Watanabe,Akiyoshi Oda,Makoto Tsukiji,Takamasa Kato,Idzumi Okajima,Takeshi Sako,M Shimada

doi:10.1051/matecconf/202133308003

Abstract

The purpose of this research was the development of a wastewater treatment technique using catalytic oxidation in superheated steam. The target substance was isopropyl alcohol (IPA). The experiment was carried out using a plug-flow reactor filled with MnO2 catalyst. The optimum decomposition condition was determined, and the kinetics of the catalytic oxidation reaction were analyzed. The experimental results were expressed as total organic carbon (TOC) removal. The dependences of the TOC removal on the reaction temperature and residence time were investigated. The TOC removal increased with the reaction temperature and residence time. It was 99.8% at 300°C, 0.9 MPa, 11 s, and oxidant ratio of 1.2. On the other hand, the TOC removal was constant for a long residence time at low reaction temperatures of 200 and 230°C. This was because acetone and acetic acid were produced via the oxidation of IPA, and they were detected as TOC. The reaction kinetics were examined using the pseudo-first-order reaction model; the TOC removal correlated well with this model. Based on the results of the kinetics, the activation energy (Ea) for TOC decomposition was determined from the Arrhenius equation; it was 56.1 kJ/mol. These results indicate that catalytic oxidation in superheated steam is useful for wastewater treatment.

Highlights

In semiconductor manufacturing, cleaning and drying processes are carried out to remove organic substances
The total organic carbon (TOC) removal increased with the reaction temperature and residence time
The TOC removal was constant for a long residence time at low reaction temperatures of 200 and 230°C

Summary

Introduction

In semiconductor manufacturing, cleaning and drying processes are carried out to remove organic substances. The organic solvent used in these processes is amphiphilic, and a high-purity solvent is used. The recovered organic solvent is not high purity, and its reuse is difficult. The wastewater is generally treated using the activated sludge method. This method has problems such as a long treatment time, the necessity of pre-treatment and post-treatment, and the generation of excess sludge. A wastewater treatment technique with a short time and less environmental load is required

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