Fouling and energy cost are two issues affecting membrane applications in water and wastewater treatment.Our research have been focused on membrane fouling control and reducing energy cost based on(i)applying the concept of critical and sustainable fluxes to guide operation,(ii)improving hydrodynamics and mixing efficiency by using controlled air bubbles,(iii)identifying fouling mechanisms to design effective cleaning based on advanced multi-photon microscopic imaging and small angle neutron scattering,(iv)identifying fouling agents and applying effective pre-treatment,(v)development of novel,low energy processes for desalination and MBR.