The aim of this research was an initial study of the feasibility of using polyvinyl (PT)-immobilized cyanobacteria for the removal of nitrate, nitrite, and phosphate from polluted potential drinking water Batch and continuous-flow air-agitated and packed-bed bioreactors were used. Continuous-flow air-agitated bioreactors showed N removal efficiencies of up to 90% for residence times of 14 h in short-term experiments. If N-starved cells were to be used practically for the removal of N and phosphate from water, several bioreactors would need to be set up in parallel, alternating cycles of N-starvation and N-supply, to maintain the system operating continuously with N-starved cells The continuous-flow ab agitated bioreactor running at 45 degrees C showed higher efficiency of N removal from water than the continuous-flow packed-bed bioreactor at room temperature. However the packed-bed bioreactor seemed to give slightly better results when phosphate removal was considered. No significant leakage of cells was observed in any of the bioreactors during operation.