Bioremediation of oxytetracycline in seawater by living and dead biomass of the microalga Phaeodactylum tricornutum

Abstract

Due to its use, a large amount of Oxytetracycline (OTC) is released into water, which has a detrimental impact on aquatic ecosystems and human health. Although there are different physicochemical methods (mainly photodegradation) to remove OTC, there is increasing interest in the use of bioremediation. The sorption characteristics of OTC using living and dead biomass of the microalga Phaeodactylum tricornutum have been investigated in this study. Kinetics, isotherms and maximum elimination capacity were tested and discussed. Kinetic studies showed that the OTC removal by living biomass followed a sigmoidal model. However, the dead biomass followed a pseudo-first order model. The living biomass showed higher efficiency than the dead biomass with maximum sorption capacities of 29.18 mg g−1 and 4.54 mg g−1, respectively. Combination of living biomass and photodegradation under the culture conditions eliminated 13.2 mg L−1 of OTC during 11 h of culture and with an initial OTC concentration of 15 mg L−1. With an initial OTC concentration of 2.5 mg L−1, 97% of OTC was removed. This removal was mainly caused by bioremediation than by photodegradation. The results proved the potential practical application of the living P. tricornutum biomass for a low-cost and efficient removal of OTC from seawater.