The present paper deals with bioaccumulation and biosorption studies of Cd (II) ions using Spirulina (Arthrospira) indica in small pilot scale open raceway ponds. The second step of bioaccumulation process described by Chojnacka and Wojciechowski [1] was modeled using Monod growth kinetics with toxic inhibition. Monod model was developed by assuming the growth limiting substrate as NaHCO3 and growth inhibitor/toxin as Cd (II). The selection of NaHCO3 as growth limiting substrate is purely based on its high concentration in the growth media (Zarrouk’s medium), when compared with other medium constituents. The percentage decrease in the Spirulina (Arthrospira) indica biomass and lethal concentration and time (LCt50) of the toxin (Cd (II)) dosage required to kill half the members of a tested population after seven days of test duration, was calculated. The biosorption potential of live S. (Arthrospira) indica to biologically remove cadmium (II) ions at low concentration (below 2 mg/L) was examfined.