Laccase-coated polyethersulfone membranes for organic matter degradation and removal

The removal of natural organic matter (NOM) from water is becoming increasingly important for water treatment plants not only to improve drinking water aesthetics such as taste and odor, but also to prevent the formation of carcinogenic disinfection by-products (DBPs). This study applies the catalytic properties of the wood degrading laccase enzyme produced by white rot fungi (WRF) on breaking down and removing organic matter in drinking water. Fungal isolates were collected and screened for their ability to degrade humic acid (HA), a NOM model compound. Highly permeable polyethersulfone (PES) membrane was used as support material for the immobilization of the lignolytic enzymes extracted from Perenniporia sp. and Polyporaceae sp. for the simultaneous degradation and removal of NOM. A 52 % humic acid removal was recorded for the Polyporaceae sp. isolate R. Results showed that addition of 4-hydroxybenzoic acid as enzyme laccase substrate had a great influence on immobilization and enzyme activity of modified membranes. Membrane wettability was found to be < 60°. The modified membrane achieved a rejection of greater than 90 % for the model compound. Enzyme activity was a function of contact time and substrate type. The attained results revealed that catalytic membranes can be an efficient alternative for the removal dissolved organic matter and membrane fouling mitigation during water treatment.