Analysis of Phosphate in Wastewater Using an Autonomous Microfluidics-Based Analyser

A portable sensor for the analysis of phosphate in aqueous samples has been developed. The sensor incorporates microfluidic technology, colorimetric detection, and wireless communications into a compact and rugged portable device. The detection method used is the molybdenum yellow method, in which a phosphate-containing sample is mixed with a reagent containing ammonium metavanadate and ammonium molybdate in an acidic medium. A yellow-coloured compound is generated and the absorption of this compound is measured using a light emitting diode (LED) light source and a photodiode detector. The absorption is directly proportional to the phosphate concentration in the original sample. In this paper we describe the application of this phosphate sensor to the analysis of wastewater at a municipal wastewater treatment plant in Co. Kildare, Ireland.

Authors:

• John Cleary
• Conor Slater
• Dermot Diamond

Keywords:

• Microfluidic
• phosphate
• sensor
• wastewater.

References:

[1] S. R. Carpenter, N. F. Caraco, D. L. Correll, R. W. Howarth, A. N.
Sharpley, and V. H. Smith, "Nonpoint pollution of surface waters with
phosphorus and nitrogen," Ecological Applications, Vol. 8, Aug. 1998,
pp. 559-568.
[2] M. Coquery, A. Morin, A. Bécue and B. Lepot, "Priority substances of
the European Water Framework Directive: analytical challenges in
monitoring water quality," Tr. Anal. Chem., Vol. 24, Feb. 2005, pp. 117-
127.
[3] P. Jordan, J. Arnscheidt, H. McGrogan, S. McCormick, "High-resolution
phosphorus transfers at the catchment scale: the hidden importance of
non-storm transfer," Hydrology and Earth System Sciences, 9, Dec 2005,
pp. 685-691.
[4] M. Bowden, M. Sequeira, J.P. Krog, P. Gravesen, and D. Diamond, A
prototype industrial sensing system for phosphorus based on micro
system technology, Analyst, Jan. 2002, 127, pp. 1-4.
[5] M. Bowden, M. Sequeira, J.P. Krog, P. Gravesen, and D. Diamond,
"Analysis of river water samples utilising a prototype industrial sensing
system for phosphorus based on micro-system technology," J. Environ.
Monit., Aug. 2002, 4, pp. 767-771.
[6] A.G. Crevillen, M. Hervas, M.A. Lopez, M.C. Gonzalez, and A.
Escarpa, "Real sample analysis on microfluidic devices," Talanta, 74,
Oct. 2007, pp. 342-357.
[7] C. Slater, J. Cleary, C. M. McGraw, W.S. Yerazunis, K.T. Lau, and D.
Diamond, "Autonomous field-deployable device for the measurement of
phosphate in natural water" Proc. of SPIE, Vol. 6755, Sept. 2007,
67550L1-67550L8.