Poster 3-40

Waihung Lo,^a Mui-Fong Wong,^b and Hong Chua^b

aDepartment of Applied Biology and Chemical Technology
The Hong Kong Polytechnic University
Hung Hom, Kowloon, Hong Kong SAR, China

bDepartment of Civil and Structural Engineering, The Hong Kong Polytechnic University,
Hong Kong, China

Telephone: +852-2766-6696; Fax: +852-2364-9932; E-mail: bctlo@polyu.edu.hk

The presence of copper ions in water poses serious environmental and human health hazards because of its toxicity, its tendency to bioaccumulate, and its abundance and persistence in the environment. Metal-processing industries must pretreat or detoxify the metal-rich effluents before discharging them into the aqueous environment. The use of biological materials for heavy metal removal or recovery has gained importance in the last decade because of their good performance and low cost. Studies were conducted to investigate the removal and recovery of copper(II) ions from aqueous solutions by Micrococcus sp., which was isolated from a local activated-sludge process. The kinetics of biosorptive removal of copper by the cells was relatively fast, with 75% of the final value attained within the first 3 min of contact. The equilibrium of copper biosorption observed the Langmuir isotherm model very well, with a maximum biosorption capacity (q_max) of 36.5 mg Cu²⁺/g dry cell reached at pH 5 and 52.1 mg Cu²⁺/g dry cell at pH 6. Micrococcus sp. exhibited high specificity towards copper compared with zinc, nickel, and chromium. Copper uptake by cells was negligible at pH 2 and then increased rapidly with increasing pH until pH 6. Cells harvested at exponential growth phase and stationary phase showed similar biosorption characteristics for copper. Sodium polyphosphate (0.1 M) and nitric acid (0.05 M) were the most efficient desorption media, recovering more than 90% of the initial copper sorbed, while the distilled, deionized water control demonstrated no copper desorption. The biomass of Micrococcus sp. may be applied to develop potentially cost-effective biosorbents for removing and recovering copper from effluents.