A green engineering approach to simultaneously removing organic and nitrogenous substances in wastewater

This study was aimed at investigating the performance of an algae bioreactor on the simultaneous removal of organic and nitrogenous substances under varied illumination period and light intensity. An aerobic bioreactor having an effective volume of three litters was operated in fill and draw mode of four days per cycle. The algae of Chlorella sp were grown in the bioreactor fed with simulated wastewater. The bioreactor received the light, which was set with a period of 12-hour light-ON, followed by 12-hour light-OFF, and a continuous 24-hour light-ON. The light intensities were varied at various levels of 5,000; 7,500; 10,000; and 12,500 lux. The result of the research showed that the algae bioreactor was capable of removing Chemical Oxygen Demand (COD) up to 57.56% at the light intensity of 5,000 lux and up to 68.83% at the light intensity of 10,000 lux. The removal of ammonium at light intensities of 5,000 and 10,000 lux was obtained as 52,42 and 73,55%, respectively. The highest algae concentration of 1.5 × 106 individual/ml was observed at the light intensity of 10,000 lux. The above results suggested that the removal of organic and nitrogenous substances has simultaneously occurred in the algae bioreactor.