One of the major goals in membrane separation technology is to develop fouling-resistant membranes that can provide a long operating time and low operation costs. This thesis aims to manufacture fouling and biofouling-resistant polymeric nanofiltration (NF) and ultrafiltration (UF) membranes using unique approaches. The first approach was to change coagulation bath composition in the phase inversion technique for manufacturing fouling-resistant polyamide-imide (PAI) based NF and biofouling-resistant polysulfone (PSF)/sulfonated polyethersulfone (PSF-SPES) based UF membranes. To this end, hydrophilic branched polyethyleneimine (PEI) dissolved in the coagulation bath allowed the preparation of a positively charged PAI based NF membrane by forming a covalent bond with the imide group in the PAI. To manufacture antibacterial UF membranes, a strong antibacterial surfactant, cetyltrimethylammonium bromide (CTAB), was dissolved in the coagulation bath and made an electrostatic interaction with SPES at the polymer/bath interface during phase inversion. Both membranes were prepared in a one-step process without using any pore formers in the casting solution. The second approach used in the thesis focused on modification of commercial polyethersulfone (PES) UF membranes with co-deposition of dopamine and CTAB molecules to impart antibiofouling behavior without compromising the pore size and pure water flux of the support. To achieve this task, during modification, an inert physical barrier was created inside the membrane pores by continuously feeding nitrogen gas (N2) from the backside of the support to prevent pore penetration. In the last approach, ultrasound as a green, controllable trigger was used for modifying PSF and PSF-SPES UF membranes with dopamine. The main purpose of using ultrasound was to accelerate the polymerization kinetics of dopamine, hence shortening the modification time.