Enhanced triclosan biodegradation by a biphasic bioreactor

Abstract

Triclosan (TCS), an antiseptic agent that facilitates the formation of microbial resistances, has been widely used and is therefore ubiquitously detectable in wastewater. However, structure and low water solubility limit both microbial transformation kinetic and removal efficiency of TCS. Therefore, the use of solubilizers or non-aqueous phases (NAP) appears to be a suitable approach for rapid, complete, and cost-effective treatment of highly contaminated TCS point sources such as sports clubs, hospitals, industrial wastewater treatment plants or synthesis effluents without dilution effects.The mixed culture TCSmix100 previously isolated and characterized, and able to completely mineralize TCS at stoichiometric chloride release, was investigated in presence or absence of solubilizers in lab-scale well stirred batch reactors. While TCS conversion was limited in solubilizer-free tests due to limited solubility of TCS crystals within the aqueous phase, solubilizers enhanced water solubility, mass transport and microbial kinetics. Thus, TCS transformation rate at initial 1.45 g TCS L−1 was further increased from a high level of 155–172 mg L−1d−1 without solubilizers to 399 mg L−1d−1 or to 888 mg L−1 d-1 providing β-pinene or α-pinene as NAPs, i.e., by a factor of 2.3–5.2, exceeding kinetic parameters of other strains described in literature by at least two orders of magnitude. These results clearly demonstrate the high TCS mineralization capacity of this biphasic treatment technologies and its applicability in treatment of highly contaminated TCS point-sources to eliminate recalcitrant contaminants at high levels before getting diluted.