Free Access
Volume 28, Number 9, November 2000
Endocrine disruptors
Page(s) 872 - 877
Section Original articles
Analusis 28, 872-877 (2000)
DOI: 10.1051/analusis:2000159

Optimization of the degradation of sewage sludge by wet air oxidation. Study of the reaction mechanism on a cellulose model compound

N. Ricq, S. Barbati and M. Ambrosio

Laboratoire de Chimie et Environnement, Université de Provence, 3 place Victor Hugo, case 29, 13331 Marseille Cedex 3, France

(Received September 19, 2000; accepted January 9, 2000.)

The aim of this work is to optimize the degradation yield of an activated sludge and to study the reaction mechanism on a cellulose model compound. This optimization is performed with a Simplex design with four parameters: reaction temperature (280-350 °C), injected air pressure (40-60 MPa), reaction time (10-45 minutes) and COD concentration (0.5-5 g L-1). The better yield obtained on TOC concentration is 82,5% at 330 °C. Over this temperature, the yield substantially decreases. The use of cellulose as a model compound for activated sludge confirms optimization results and leads to the identification of by-products and free radical species participating in the reaction. Two major organic compounds have been detected: 4-oxo pentanoïc acid and 3-oxo butanoïc acid, and three types of radicals: HO°, CO $_2^{\circ -}$ and °CH(OH)CH3.

Key words: Wet air oxidation -- sewage sludge -- optimization -- by-products -- free radicals.

© EDP Sciences, Wiley-VCH 2000

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