Application of ZnO nanostructures in ceramic and polymeric membranes for water and wastewater technologies: A review

•ZnO has been postulated as a filler in polymeric and ceramic membranes.•Recent progress on ZnO nanostructure preparation and characterization is reported.•Environmental applications using ZnO-embedded polymeric/ceramic membranes are included.•Approaches to control membrane properties to reduce fouling and biofouling are also covered.