Copper biosorption in an aerobic bioreactor

This study evaluates the biosorption of copper by aerobic biomass that was selected from surface waters of the San Pedro River in Sonora, Mexico. Using a batch system, 73% biosorption of copper was obtained in 75 minutes. Continuous biosorption assays were carried out for 133 days in an ascending flow aerobic reactor packed with zeolite (AFAR-PZ) that was inoculated with a bacterial consortium. Strains were grown until 1 g L^-1 of biomass was obtained. Tests using continuous biosorption were performed as follows: (i) the addition of 50 mg Cu²⁺ L^-1 without recirculation of biomass; (ii) the addition of 20 mg Cu²⁺ L^-1 without recirculation of biomass; and (iii) the biomass were recirculated with the addition of 20 mg Cu²⁺ L^-1 to pH 3 to 4. The fourth and fifth assays varied pH between 4 and 5, with 20 mg Cu²⁺ L^-1 and the biomass recirculated. Biosorption capacity of the first and second assays was 96% on the first day of experimentation. During the third trial 97% of biosorption was obtained during 6 days and the process was improved by varying the pH. Copper biosorption equilibrium was investigated under the same operating conditions. Langmuir adsorption isotherms were used to fit experimental data. The biosorption capacity of aerobic biomass was 3.08 mmol g^-1. It was demonstrated that this biomass is capable of biosorbing copper and this method has potential for the treatment of industrial effluents contaminated with heavy metals.