Biological Nutrient Removal in an Intermittently Aerated Bioreactor

The extension of biological processes from carbonaceous impurities removal to nitrogen and phosphorus removal had an impact on the biological system configuration. The system must be well designed, optimized, and operated at its optimum in order to meet the ever more stringent effluent standards. An intermittently aerated completely mixed lab-scale activated sludge bioreactor (IACMB) has been used for modelling biological processes of nutrients removal. Concerning the nitrogen removal, the operating cycles 15-30 (15 minutes of aeration, 30 minutes of only mixing without aeration) and 30-30 were tested. For the experiments with luxury uptake processes, the operating cycles 15-45,15-90,30-60 and 15-75 were used. The cycle 15-75 was the most satisfactory with convenient lengths of aerobic, anoxic, and anaerobic period, high efficiency of the nitrification and denitrification processes, and significant decrease in phosphorus concentration. The results have shown that the intermittently aerated bioreactors are suitable for nitrogen removal as well as luxury uptake of phosphorus. The main advantage is high flexibility in maintenance and control of biochemical environments in the bioreactor.