The extraction of Chitin was carried out from Aspergillus niger mycelium. This polymer was characterized by elemental analysis, Fourier Transformed Infrared spectroscopy, nuclear magnetic resonance and viscometric molar mass determination (Mv). The deacetylation degree was determined for two different samples by elemental analysis and potentiometric titration, obtaining 79.78 and 80.68%, respectively. Chitosan obtained from the deacetylation process was employed to run flocculation and coagulation tests with samples from water of the Melendez river. The flocculation was successful allowing reduction of the amount of the primary coagulant (Ferric chloride) up to 50% without any significant change. Retention of metallic ions such as copper, nickel and lead by chitosan was evaluated by adsorption isotherm plots. It was found from kinetic studies that copper and lead follow the Langmuir type isotherm, and Nickel follows a Freudlinch type isotherm.