Effect of linear alkylbenzene sulfonate on Cu2+ removal by Spirulina platensis strain ( FACHB-834).

The removal efficiency of Cu²⁺ by Spirulina platensis (strain FACHB-834), in viable and heat-inactivated forms, was investigated in the presence and absence of linear alkylbenzene sulfonate ( LAS). When the initial Cu²⁺ concentration was in the range of 0.5-1.5 mg · L⁻¹, a slight increase in growth rate of FACHB-834 was observed. In contrast, when Cu²⁺ or LAS concentrations were at or higher than 2.0 or 6.0 mg · L⁻¹, respectively, the growth of FACHB-834 was inhibited and displayed yellowing and fragmentation of filaments. The presence of LAS improved Cu²⁺ removal by ~20%, and accelerated attainment of Cu²⁺ retention equilibrium. For the 2- mg · L⁻¹ Cu²⁺ treatments, retention equilibrium occurred within 2 d and showed maximum Cu²⁺ removal of 1.83 mg · L⁻¹. In the presence of LAS, the ratio of extracellular bound Cu²⁺ to intracellular Cu²⁺ taken up by the cells was lower (1.05-2.26) than corresponding ratios (2.46-7.85) in the absence of LAS. The percentages of extracellular bound Cu²⁺ to total Cu²⁺ removal (both bound and taken up by cells) in the presence of LAS ranged from 51.2% to 69.3%, which was lower than their corresponding percentages (71.1%-88.7%) in the absence of LAS. LAS promoted biologically active transport of the extracellular bound form of Cu²⁺ into the cell. In contrast, the addition of LAS did not increase the maximum removal efficiency of Cu²⁺ (61.4% ± 5.6%) by heat-inactivated cells compared to that of living cells (59.6% ± 6.0%). These results provide a theoretical foundation for designing bioremediation strategies using FACHB-834 for use in surface waters contaminated by both heavy metals and LAS. [ABSTRACT FROM AUTHOR]