Equilibrium and kinetic studies of lead biosorption by three Spirulina (Arthrospira) species in open raceway ponds

The present investigation deals with the biosorption of lead from aqueous solutions in open race way pond using edible and live Spirulina (Arthospira) maxima, Spirulina (Arthospira) indica, Spirulina (Arthospira) platensis. Studies on various initial lead (II) ion concentrations, biosorbent dosage, pH and bioaccumulation potential were evaluated. The organisms are tolerant up to 4 mg/l and after that slight growth inhibition was found. Spirulina (Arthospira) indica showed more tolerance when compared with Spirulina (Arthospira) maxima and Spirulina (Arthospira) plantensis. The adsorption rate data was fitted to pseudo second order kinetics. The Langmuir and Freundlich models were applied to the experimental data and their equilibrium parameters were determined. Further optimization of initial lead (II) ion concentration, solution pH, agitation speed and biosorbent dosage were done using Box-Behnken experimental design coupled with artificial neural networks. This study provides a deep insight for exploring potential of using algal open race way ponds for biosorption of heavy metals. The diversity of the results can be expanded still further for other algal species and heavy metals.