title: UV spectrophotometry for monitoring the performance of a yeast-based deoxygenation process to treat ships' ballast water.
abstract: This study assessed the usefulness of UV spectrophotometry for the monitoring of a yeast-based deoxygenation process proposed for ships' ballast water treatment to prevent the transfer of aquatic invasive species. Ten-day laboratory experiments using three treatment concentrations and different water types were conducted and resulted in complete oxygen depletion of treated waters. The treatment performance and quality of treated waters were determined by measuring the UV-visible absorbance spectra of water samples taken over time. Samples were also used for laboratory analysis of water quality properties. The UV absorbance spectra values were strongly correlated (r = 0.96) to yeast cell density in treated waters. The second-order derivative (D (2)) of the spectra varied greatly over time, and the spectrum profiles could be divided into two groups corresponding to the oxygenated and anoxic phases of the treatment. The D (2) value at 215 nm was strongly correlated (r = 0.94) to ammonia levels, which increased over time. The D (2) value at 225 nm was strongly correlated (r > 0.97) to DO concentration. Our results showed that UV spectrophotometry may provide a rapid assessment of the behavior and performance of the yeast bioreactor over time by quantifying (1) the density of yeast cells, (2) the time at which anoxic conditions were reached, and (3) a water quality index of the treated water related to the production of ammonia. We conclude that the rapidity of the technique confers a solid advantage over standard methods used for water quality analysis in laboratory and would permit the direct monitoring of the treatment performance on-board ships.
authors.affiliation: Direction des expertises et des études, Centre d'expertise en analyse environnementale du Québec, Ministère du Développement durable, de l'Environnement et de la Lutte contre les changements climatiques, 2700, rue Einstein, 2sd Floor (B.2.304), G1P 3W8, Québec, Quebec, Canada.
authors.forename: Éloïse
authors.initials: É
authors.lastname: Veilleux
authors.affiliation: Water Sciences and Technology Directorate, Environment Canada, Centre Saint-Laurent, 105 McGill Street, 7th Floor, Montréal, H2Y 2E7, Quebec, Canada. yves.delafontaine@dfo-mpo.gc.ca.|Direction régionale des Sciences, Institut Maurice-Lamontagne, Pêches et Océans Canada, 850 Route de la Mer, C.P. 1000, Mont-Joli, Quebec, G5H 3Z4, Canada. yves.delafontaine@dfo-mpo.gc.ca.
authors.forename: Yves
authors.initials: Y
authors.lastname: de Lafontaine
authors.affiliation: LERES, EHESP, Avenue du Professeur Léon-Bernard CS 74312, 35043, Rennes, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Thomas
mesh_terms: D000818:Animals; D004784:Environmental Monitoring / Q000379:methods*; D058865:Introduced Species; D010084:Oxidation-Reduction; D010100:Oxygen / Q000032:analysis; D012767:Ships; D013053:Spectrophotometry; D014466:Ultraviolet Rays; D014871:Water Microbiology; D018508:Water Purification; D060753:Water Quality; D015003:Yeasts / Q000502:physiology*
chemical_list: D010100:Oxygen
keywords: Ballast water treatment; Biological deoxygenation; UV spectrophotometry; Yeast bioreactor