The siliceous microalga Navicula subminuscula (Manguin) as a biomaterial for removing metals from tannery effluents: A laboratory study

The ability of the diatom navicula subminuscula (manguin) to remove hexavalent chromium [cr(vi)] was investigated in a batch system by the determination cr(vi) toxic effects and biosorption by this species. the experiments have been performed under varying ranges of ph,contact time and initial ion concentrations. the results show a significant growth of navicula subminuscula for cr concentrations up to 10mg l-1. the growth rate decreases as a function of increasing concentrations of cr(vi). the ic50 is 9.2 mg l-1 for the artificial growth medium tested which is more than that calculated with river water (4.45mg l-1) and tannery effluent water (0.088mg l-1). the percentage of cr(vi) biosorption increases with the decrease of ph: 50 % biosorption was measured at ph 7 whereas 92 % was reached at the extreme acid ph. the found linear plot of ceq/q vs ceq shows that biosorption follows the langmuir biosorption model. the correlation coefficient was 0.993. at an initial concentration of 0.4g dried diatoms per liter with an initial cr(vi) concentration of 20mg l-1,the values for qmax and b were determined from the slope and intercept of the plot,and were found to be 94.97mg cr(vi) per g of diatoms and 0.16l mg-1,respectively. the wide ecological valence of this diatom to pollution parameters and the seasonal pattern of its life cycle are the main factors that make the biomonitoring of cr(vi) by this species feasible. © 2017,university of mohammed premier oujda morocco.