Continuous metal bioremoval by new bacterial isolates in immobilized cell reactor

In this study, four bacterial species isolated from an industrially polluted region at the Istanbul–Kocaeli border were characterized and their efficiencies for bioremoval of Cu²⁺, Ni²⁺, Cr³⁺, Zn²⁺, and Fe²⁺ were determined in batch and continuous systems. Strain N4c was used for continuous metal bioremoval in a packed-bed immobilized cell reactor (ICR) with a working volume of 180 ml. ICR was successfully operated for treatment of synthetic wastewater containing 200 mg/l Cu²⁺ and Ni²⁺ for 140 and 80 h, respectively. Bioremoval efficiency of ICR for Cu²⁺ reached around 90 % in the last 3 days of operation at a flow rate of 1 ml/min. Ni²⁺ bioremoval in ICR was less efficient as the system worked for only 80 h and bioremoval efficiency decreased from 73.3 to 42.8 % during the operation period. Wastewater containing one or two types of metal seems to be a good candidate for treatment with immobilized N4c cells in a continuous system. Survival of the cells in the wastewater was found to be an important parameter affecting bioremoval efficiency in both batch and continuous systems. The ICR used in this study can be scaled up for treatment of industrial wastewaters containing Ni²⁺ or Cu²⁺.