Biosorption of Cu(II) ions from synthetic and actual wastewater using three algal species

摘要

The use of three freshwater microalgal cultures--Chlorella sorokiniana, Anabaena laxa, and Hapalosiphon welwitschii--for sorption of copper(II) from synthetic Cu(II) solutions and Marinduque, Philippines, wastewater was studied. The optimum amount of biomass for the three species was 0.025 g dry weight. The optimum contact time for both C. sorokiniana and A. laxa was 1 h, whereas that of H. welwitschii was 30 min. All three species exhibited maximum Cu(II) sorption at pH 4.0-6.0. The Langmuir adsorption isotherm was the best fit model for the three species. The three cultures were found to be effective biosorbents when used in synthetic wastewaters of low concentration (10-30 ppm). Maximum Cu(II) reductions obtained were 88.2, 88.6, and 91.7% for the C. sorokiniana, A. laxa, and H. welwitschii cultures, respectively. C. sorokiniana, A. laxa, and H. welwitschii removed 5.70, 11.16, and 7.15% of Cu(II), respectively, when applied to wastewater taken from Consolidated Mines Inc. (CMI) containing around 150 ppm Cu(II). C. sorokiniana and A. laxa, in combination, exhibited 14.05% Cu(II) removal from CMI wastewater. Desorption with 0.11 M HCl effected 73.20, 64.54, and 70.85% removal of Cu(II) from the surfaces of C. sorokiniana, A. laxa, and H. welwitschii, respectively. SEM-EDS spectra of the three species confirmed the presence of Cu(II) on their surfaces.