On-line analysis of volatile fatty acids in anaerobic treatment processes

Edwin Palacio-Barco; Fabien Robert-Peillard; Jean-Luc Boudenne; Bruno Coulomb

doi:10.1016/j.aca.2009.12.019

On-line analysis of volatile fatty acids in anaerobic treatment processes

Anal Chim Acta. 2010 May 23;668(1):74-9. doi: 10.1016/j.aca.2009.12.019. Epub 2009 Dec 22.

Authors

Edwin Palacio-Barco¹, Fabien Robert-Peillard, Jean-Luc Boudenne, Bruno Coulomb

Affiliation

¹ Université de Provence-CNRS, Laboratoire Chimie Provence-UMR6264, Equipe Chimie de l'Environnement Continental, 3 place Victor Hugo, case 29, 13331 Marseille cedex 3, France.

PMID: 20457305
DOI: 10.1016/j.aca.2009.12.019

Abstract

In this paper, an on-line spectrofluorimetric system is proposed for a simple, rapid and accurate measurement of volatile fatty acids (VFA) in anaerobic treatment processes. The determination method is based on the derivatization of VFA with N-(1-naphthyl)ethylenediamine (EDAN) followed by a spectrofluorimetric detection of the corresponding amide. The analytical procedure is automated with a flow analysis technique, coupling multisyringe (MSFIA) and multi-pumping (MPFS) methods. Operative conditions have been investigated with a special attention paid to the activation and amidation steps and to the liquid-liquid extraction of the derivatized final product. Fluorescence intensities (lambda(em)=335 nm, lambda(ex)=395 nm) were found to be proportional to the concentration of VFA, expressed as acetic equivalent, in the range 19-1000 mg L(-1), with a detection limit (3sigma) of 5.1 mg L(-1). Our results showed a good selectivity for VFA as compared to other organic and inorganic compounds usually found in sewage sludges. Validation of the on-line system developed has been assessed by application of the procedure to aqueous samples originating from sewage sludge treatment plants. The results were in good agreement with ion chromatography measurements.