Light conducting photocatalytic membrane for chemical-free fouling control in water treatment

Abstract

This work shows for the first time the convenient in-situ UV illumination of a titanium dioxide (TiO2) photocatalytic membrane via a sintered porous glass substrate for effective fouling reduction during water treatment. By directing light through the light conducting glass substrate, this concept overcomes the current challenge of photocatalytic membranes that direct light through turbid, light obstructing feed waters. Fouling was tested by filtering model solutions of humic acid (HA), bovine serum albumin (BSA) or sodium alginate (SA). Photocatalysis initiated by simply directing light via the permeate side through the porous glass substrate led to significant reductions in trans-membrane pressure (TMP) rise rates between backwashes and all model organic fouling compounds. Specifically, the UV-light exposed membranes showed a 3.0-fold and 2.4-fold reduction in total filtration resistance for BSA and SA solutions, respectively, which also showed 2.7-fold and 4.2-fold reductions in the irreversible fouling indices. Analysis by SEM coupled with fouling modelling showed the beneficial anti-fouling effects stemmed from reduced intrusion of organic material inside the TiO2 membrane pores, as well as reduced cake layer resistance. The novel, convenient light conducting photocatalytic membranes concept could be used for sustainable, low-chemical membrane filtration of polluted water.