**Abstract**

Human activities have led to the entry of various pollutants into rivers, seas, and oceans. Various methods are used to remove pollution, one of them is using biopolymers including alginate obtained from brown algae. Due to their special structure and physical properties, availability, biocompatibility, and biodegradability, they can be considered adsorption materials. Alginate hydrogel, composite, and nanocomposite could eliminate methyl violet dye and heavy metals, such as Pb2 **+**, Cd2 **+**, Sr2 **+**, Cu2+, Zn2+, Ni2+, Mn2+, Li2+, and Pb2+. The immobilized microalgal cells in alginate exhibited higher removal efficiency of pollutants from the wastewater as compared to the suspended free cells of microalgal culture and alginate alone. The immobilization of the microalgal cells using alginate could eliminate palm oil, ammonium, phosphate, etc. More research needs to be done but according to researchers, alginate can be a safe substance to remove pollutants from the environment.

**Keywords:** alginate, wastewater treatment, microalga, contaminants, alginate-based hydrogel
