The principal objective of this study is to develop and evaluate membranes based on cellulose derivatives for water treatment applications. In the first phase, cellulose triacetate (CTA) was synthesized through a chemical modification process involving the esterification of natural cotton, collected from the Ghardaia region, using acetic anhydride as an acetylating agent. The resulting CTA polymer was then used to fabricate membranes either in their pure form or blended with another biodegradable polymer—chitosan—through a phase inversion technique. The synthesized CTA was structurally characterized using Fourier Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance (1H-NMR), and Carbon-13 NMR (13C-NMR). The resulting membranes were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) to investigate their surface morphology and elemental composition. The structural analyses confirmed the successful acetylation of cellulose and the formation of CTA. The pure CTA membrane exhibited a dense structure with small pore sizes, making it suitable for microfiltration applications. In contrast, the membranes made from chitosan and chitosan/CTA blends showed smoother surfaces and smaller, more uniform pores, making them more appropriate for nanofiltration. The addition of chitosan significantly altered the membrane morphology, enhancing its potential for selective separation. These findings suggest that the developed membranes hold strong promise for future testing in wastewater treatment and environmental remediation applications.