Biosorption of lead and copper from contaminated solutions by the cyanobacteria -- Spirulina maxima

Toxic metal waste (TMW) generated due to anthropogenic activities is a major environmental concern. TMW poses a major threat to human health by leaching into groundwater as well as contaminating surrounding vegetation causing heavy metal poisoning in both herbivores and carnivores. To alleviate the problems caused by heavy metal contamination, the prokaryotic cyanobacteria, Spirulina maxima (Spirulina) can be used as a part of an efficient and viable alternative bioremediation technique. The objective of this study was to investigate S. maxima’s potential for bioremediation by examining its tolerance and absorption/adsorption capacity from lead and copper contaminated aqueous solution using initial concentrations of 0.5 and 2.0 ppm in single and dual metal systems. To determine the tolerance of Spirulina, the growth was examined in copper and lead contaminated solutions. The cells showed better survival capability in copper contaminated solutions compared to lead. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the possible functional groups present on the surface of Spirulina that participated in the metal binding. Metal biosorption by Spirulina was dependent mainly on the functional groups of OH-, COO-, and amide/amine. Confocal Laser Scanning Microscopy coupled with [lowercase letter lamda] scan was used to determine the pigment intensity of S. maxima in presence of metals. The results indicated the inhibition of fluorescence intensity in metal treated cells during biosorption. The study revealed that S. maxima has the potential for tolerance and biosorption ability on both copper and lead solution. These features make S. maxima as a better biosorbent to remove TMW from contaminated water.