Zinc-Containing Effluent Treatment Using Shewanella xiamenensis Biofilm Formed on Zeolite

The sorption properties of Shewanella xiamenensis biofilm formed on zeolite (mineral-organic sorbent) as a sorbent have been investigated aiming to determine its suitability for complex zinc-containing effluent treatment. The optimum conditions for metal sorption from synthetic solutions were evaluated by changing the pH, zinc concentration, temperature, and time of sorption. The highest removal of metal ions was attained at pH range 3.0-6.0 within 60-150 min of sorbent-sorbate contact. The results obtained from the equilibrium studies were described using the Langmuir, Freundlich, and Temkin models. Maximum sorption capacity of the sorbent calculated from the Langmuir model changed from 3.4 to 6.5 mg/g. High coefficient of determination values calculated for pseudo-second-order and Elovich models indicate the predominant role of chemisorption in metal removal. Gibbs energy and ∆H° values point at the spontaneous and endothermic character of the sorption. The effect of pH and biosorbent mass on Zn(II) sorption from industrial effluent with an initial Zn(II) concentration of 52.8 mg/L was tested. Maximum removal of zinc ions (85%) was achieved at pH 6.0 by applying a two-step treatment system.