Alginate-based biotechnology: a review on the arsenic removal technologies and future possibilities

The alginate-based adsorption technologies have emerged as potential methods for arsenic removal from drinking water. The adsorbents (iron oxide, hydroxide, nano zero valent iron (nZVI), industrial waste, minerals, magnetite, goethite, zirconium oxide, etc.) are impregnated into alginate beads to produce the media. The biocompatibility, rough surface with large area, and amorphous and high water permeable bead structure improve arsenic adsorption efficiency while the regeneration process is simpler than the conventional adsorbents. In recent years, studies have reported laboratory-scale applications of alginate beads, encapsulated and impregnated with adsorbents, for arsenic removal from drinking water. The arsenic removal efficiencies were reported to be over 95% with a wide range of concentrations (10-1,000 parts per billion) and pH (3.0-7.5). However, commercial-and/or mass-scale applications have not been reported yet, due possibly to overall cost, complexity, reusability, and arsenic waste-laden sludge management. In this paper, research achievement on arsenic removal using alginate-based adsorbents has been reviewed. The review was performed in context to alginate bead development, adsorbent encapsulation and impregnation, application, performance, and regeneration. The advantages and limitations of the methods were analyzed and the scopes of future research were identified for mass scale domestic and industrial applications.