In this study, the efficiency of alginate-coated chitosan nanoparticles (Alg-CS-NPs) for removal of heavy metals from industrial effluents was investigated. To this end, the researchers constructed a reactor containing biomass, using response surface methodology (RSM) for process optimization. Reactor tests were carried out with both synthetic and industrial effluents containing nickel. The optimum conditions to achieve maximum removal efficiency (RE) rates for both synthetic and industrial effluents were specified for contact time (0-120 min), pH level (1-9), biomass dose (0.1-0.9 g), and initial metal ion concentration (10-90 mg/L). It was determined that 94.48% of the nickel could be removed at pH = 3, 70 mg/L initial nickel concentration, a dose of 0.3 g biomass, and 30 min contact time. The kinetic data fit well to a pseudo second-order model and the equilibrium data of the metal ions could be described well with Freundlich isotherm models. (C) 2016 Elsevier Ltd. All rights reserved.