Application of laccase and hydrolases for trace organic contaminants removal from contaminated water

Abstract

• 14 out of 22 TrOCs monitored were effectively removed (> 50 %) after 24 h by the laccase of Trametes hirsuta. • 16 out of 22 TrOCs monitored were effectively removed (> 50 %) after 24 h by the mixture of hydrolases. • Both laccase and the hydrolase mixture achieved high TrOC removal under the operational conditions encountered in real wastewater. The potential of a laccase from Trametes hirsuta , a hydrolase mixture of amylase, lipase cellulase and protease, was studied for the removal of a set of trace organic contaminants (TrOCs) at 10 µg/L each in a contaminated water. An attempt was also made to develop a combination of cross-linked enzyme aggregates (combi-CLEA) from the two groups of enzymes. After a 24-hour in batch treatments at 22°C and pH 7, compounds such as acetaminophen and levothyroxine showed a decrease in concentration of 97% and 99% respectively, in presence of laccase, while amlodipine, levothyroxine, and trimethoprim were removed at 98%, 99% and 99% respectively, when the contaminated water was treated with the hydrolase mixture. The study of the impact of pH, temperature and contact time revealed that the most favorable temperatures were 22°C and 30°C, but no clear correlation was found between pH and removal in the pH range of 6-8, although high removals were achieved at these pHs. Finally, except few compounds such as acetaminophen, the TrOC removal after 24 h was higher than that obtained in 4 h.