Experimental Design for Removal of Fe(II) and Zn(II) Ions by Different Lactic Acid Bacteria Biomasses

This paper investigates the removal of iron and zinc from aqueous solution with dairy wastewater in three different biomasses such as Lactobacillus delbrueckii ssp bulgaricus (Lb-12), Streptococcus thermophillus (STM-7) and a combination of both this bacteria culture (YC-380) and the optimization of removal efficiency using MINITAB program. A full 23 factorial design of experiments was applied to determine the optimum conditions of removal of Fe(II) and Zn(II) from aqueous solution. The three tested factors were biomass concentration (5-15 g/L), pH (3-9), and temperature (20-40 °C). The optimum biomass concentration, pH and temperature were found to be 15 g/L, 9 and 20 °C, respectively. Under optimal value of process parameters, 90- 100% Fe(II) and 70-90% Zn(II) removal were obtained with all tested biomasses. Removal results indicated that a combination of both this bacteria might be a promising biomass alternative to ST-M7 and Lb.12 in removing Zn(II) and Fe(II) ions from waters.