Polydopamine-assisted one-step immobilization of lipase on α-alumina membrane for fouling control in the treatment of oily wastewater

•The one-step immobilization had similar enzyme loading to the two-step method.•Membrane hydrolytic activity was similar for the one-step and the two-step methods.•The lipase immobilized by the one-step method showed enhanced operational stability.•The membranes modified by both methods showed strong oil-fouling resistance.•The one-step modified membrane had a higher permeance recovery after cleaning.