Improved disinfection byproduct removal using a polysulfone membrane loaded with powdered activated carbon

Powdered activated carbon was immobilized by casting it in a polysulfone polymer membrane, which was then tested for disinfection byproduct (chloroform) and bacteria (Escherichia coli) removal. The membrane prepared using 90% T20 carbon and 10% polysulfone (M20-90) provided a filtration capacity of 2783 L m-2 , adsorption capacity of 2.85 mg g-1 , and 95% chloroform removal in a 10 s empty bed contact time. Flaws and cracks on the membrane surface caused by the carbon particles appeared to reduce chloroform and E. coli removal. To overcome this challenge, up to six layers of the M20-90 membrane were overlapped, which improved chloroform filtration capacity by 94.6%, to 5416 L m-2 , and increased the adsorption capacity by 93.3%, to 5.51 mg g-1 . E. coli removal also increased from 2.5 logs reduction using a single membrane layer to 6.3 logs using six layers under 10 psi feed pressure. The filtration flux declined from 6.94 m3 m-2 day-1 psi-1 for a single layer (0.45 mm thick) to 1.26 m3 m-2 day-1 psi-1 for the six-layer membrane system (2.7 mm thick). This work demonstrated the feasibility of using powdered activated carbon immobilized on a membrane to improve chloroform adsorption and filtration capacity while simultaneously removing microbes. PRACTITIONER POINTS: Powdered activated carbon was immobilized on a membrane to improve chloroform adsorption and filtration capacity while simultaneously removing microbes. Membranes made with the smaller carbon particles (T20) delivered better chloroform adsorption performance. Use of multiple layers of the membrane further improved chloroform and Escherichia coli removal.