title: Biodegradation of thiomersal containing effluents by a mercury resistant Pseudomonas putida strain.
abstract: Thiomersal, a toxic organomercurial with a strong bactericidal effect, is the most widely used preservative in vaccine production. As a result, vaccine production wastewaters are frequently polluted with thiomersal concentrations above the European limit for mercury effluent discharges for which there is, presently, no remediation technology available. This work proposes a biotechnological process for the remediation of vaccine production wastewaters based on the biological degradation of thiomersal to metallic mercury, under aerobic conditions, by a mercury resistant bacterial strain. The kinetics of thiomersal degradation by a pure culture of Pseudomonas putida spi3 was firstly investigated in batch reactors using a thiomersal amended mineral medium. Subsequently, a continuous stirred tank reactor fed with the same medium was operated at a dilution rate of 0.05 h(-1), and the bioreactor performance and robustness was evaluated when exposed to thiomersal shock loads. In a second stage, the bioreactor was fed directly with a real vaccine wastewater contaminated with thiomersal and the culture ability to grow in the wastewater and remediate it was evaluated for dilution rates ranging from 0.022 to 0.1 h(-1).
authors.affiliation: REQUIMTE/CQFB, Department of Chemistry, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: Raquel
authors.initials: R
authors.lastname: Fortunato
authors.forename: João G
authors.initials: JG
authors.lastname: Crespo
authors.forename: M A M
authors.initials: MA
authors.lastname: Reis
mesh_terms: D001673:Biodegradation, Environmental; D019149:Bioreactors; D007220:Industrial Waste; D008628:Mercury / Q000032:analysis / Q000378:metabolism; D011310:Preservatives, Pharmaceutical / Q000032:analysis / Q000378:metabolism*; D016958:Pseudomonas putida / Q000378:metabolism*; D013849:Thimerosal / Q000032:analysis / Q000378:metabolism*; D014612:Vaccines; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D007220:Industrial Waste; D011310:Preservatives, Pharmaceutical; D014612:Vaccines; D014874:Water Pollutants, Chemical; D013849:Thimerosal; D008628:Mercury