Biological organomercurial removal from vaccine production wastewaters by a Pseudomonas putida strain

Vaccine production effluents are frequently polluted with thiomersal, a highly toxic organomercurial compound, 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 strain, in batch culture and using a synthetic wastewater, is presented and discussed. Additionally, a continuous stirred tank reactor (CSTR) fed with the synthetic wastewater was operated, and the bioreactor performance and robustness, when exposed to thiomersal shock loads, was evaluated. Finally, a CSTR for the biological treatment of a real vaccine production effluent was set-up and operated at different dilution rates.