Laccase-Coated Polyethersulfone Membranes for Organic Matter Degradation and Removal

Natural organic matter (NOM) removal from water is getting progressively significant for water treatment plants not only  to improve drinking water aesthetics such as taste and smell, but also to avoid disinfection by-products (DBPs) formed  during disinfection by chlorine. 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. White rot fungi  isolates were collected and examined for their ability to degrade humic acid (HA), a NOM model compound. Highly  permeable polyethersulfone (PES) membrane was prepared following the phase inversion process and used as material to support the immobilization of the lignin-degrading enzymes extracted from Perenniporia sp. and Polyporaceae sp. for  NOM degradation and removal. A 52 % humic acid removal was recorded for the Polyporaceae sp. The addition of  laccase substrate 4-hydroxybenzoic acid showed a great impact on the hydrophilicity of the membranes as a decrease in  contact angle measurements of <60 was achieved. Moreover, modified membrane’s immobilization yield and enzyme  activity also improved. 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 NOM removal and membrane fouling alleviation during water treatment.