The potential application of the cyanobacterium Plectonema boryanum was investigated for the removal of ammonia from aqueous solution to meet the target concentration of below 0.02 mg/L free ammonia. This method can be applied as a final polishing step in a series of wastewater treatment steps to reduce the ammonia concentration to drinking water levels. The experiments were conducted in a 2 L photobioreactor using batch and semi-batch modes of operation. The effect of important growth parameters such as temperature, light intensity and pH were investigated to identify their relative significance in a batch photobioreactor. Concentrations of ammonia in aqueous samples were varied up to 420 mg/L to study ammonia removal rates and growth of the cyanobacterium. The ammonia removal rates and maximum growth rates of the cyanobacterium were calculated and compared with other studies reported in literature. Repeated fed-batch experiments demonstrate the viability of the process to reduce free ammonia in aqueous solutions to less than 0.02 mg/L. The results of this study demonstrate the potential application of cyanobacteria technology for ammonia removal at 100 mg/L of total ammonia and greater.