Evaluation of the joint removal of nitrogen and phosphorus in an activated sludge wastewater treatment plant with continuous flow

Abstract

Sanitary effluents have increasingly been noticed as a valuable source of resources to be recovered through treatment, so much so that Sewage Treatment Plants are progressively conceived as Water Resource Recovery Facilities. For the treatment of effluents to enable the recovery of resources, it is essential that the process ensures the removal of nutrients, mainly nitrogen and phosphorus, which is usually not achieved through secondary treatment. Activated sludge systems are the most widespread for domestic wastewater treatment in Brazil, for that reason the development of techniques and adaptations to such systems aiming to promote the removal of nutrients is strategic to promote a widespread recovery of water resources. Studies show that simultaneous nitrification and denitrification is possible under controlled conditions of aeration and sludge age. More recently, phosphorus removal in these same biological system trough sidestream processes has been shown to be feasible, but its application in full-scale activated sludge systems under tropical climate still needs further studying. In the present project, different conditions of aeration, sludge age, sludge return rates, and hydraulic detention time of the digested sludge in a full-scale wastewater treatment plant will be evaluated, aiming to assess nitrogen and phosphorus removal, as well as general stability conditions of the process and reduction of energy consumption. This study intends to advance the theoretical knowledge and the understanding of operational aspects that allow the removal of nitrogen and phosphorus, in a way to contribute to the adaptation of Sewage Treatment Plants to the approach of resource recovery. (AU)