For a long time, humans have used cellulose, as a natural, renewable, and transformative polymer, for scientific development to create new technologies. Cellulose is the most abundant biopolymer on Earth, accounting for more than 50% of terrestrial biomass. For this reason, the treated cellulose (cellulose acetate (CA)) was used in the membrane preparation for water desalination. However, membrane preparation has recently attracted big attention of several research groups. In this case, cellulose acetate (CA), as an inexpensive hydrophilic biopolymer, was chosen as a polymer for preparing the membranes via the inversion phase, since it offers an efficient purification benefit with low energy consumption and less cost. The purpose of this chapter is to describe the various types of membrane preparation based on cellulose acetate, with pathogens, bacteria, and heavy metal (cadmium), and the applications of these membranes in the treatment of contaminated water, to ensure a clean water supply for both human and industrial uses.