Comparing the effects of pre-deposited and pre-mixed powdered activated carbons on algal fouling during ultrafiltration

•Cells and powdered activated carbon (PAC) layer improved the permeate quality.•A layer of PAC alone was ineffective in removing extracellular organic matter (EOM).•Pre-deposited PAC layer accommodated much more EOM than pre-mixed PAC layer.•NaClO cleaning increased the attractive force between PAC and membranes.•Pre-mixed PAC had a stronger ability to inhibit cell growth than pre-deposited PAC.