Effect of linear alkylbenzene sulfonate on Cu 2+ removal by S pirulina platensis strain ( FACHB ‐834)

The removal efficiency of Cu 2+ by S pirulina 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 Cu 2+ 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 Cu 2+ 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 Cu 2+ removal by ~20%, and accelerated attainment of Cu 2+ retention equilibrium. For the 2‐ mg · L −1 Cu 2+ treatments, retention equilibrium occurred within 2 d and showed maximum Cu 2+ removal of 1.83 mg · L −1 . In the presence of LAS , the ratio of extracellular bound Cu 2+ to intracellular Cu 2+ 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 Cu 2+ to total Cu 2+ 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 Cu 2+ into the cell. In contrast, the addition of LAS did not increase the maximum removal efficiency of Cu 2+ (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 .