Advanced biological phosphorus removal using a series of sequencing batch reactors

摘要

The biological process is for treating wastewater in order to remove the phosphorus therefrom and thus obtain clarified water. The process is using two sequencing batch reactors (SBR) in series filled with a sludge- mixed liquor. The process consists of: continuously feeding wastewater into the first (SBR) operating under anaerobic conditions for equalization and anaerobic treatment by controlling in- time any fermentation reaction occurring therein in order to produce an acidogenesis fermenting phase of organic materials and prevent the methanogenesis phase. Then, the fermented wastewater from the first SBR is rapidly transferred by batch into the second SBR. In the second SBR, the wastewater is first anaerobically treated to store a maximum amount of volatile fatty acids (VFAs) in the phosphorus removal biomass. Then, the fermented wastewater is mixed and aerated for causing the phosphorus removal biomass to rapidly consume the volatile fatty acids stored therein and to absorb the phosphorus in solution in the wastewater, thereby producing a phosphorus-rich sludge-mixed liquor. Then, the phosphorus-rich sludge-mixed liquor is removed under oxygenated conditions to avoid resolubilization of the phosphorus in the water. The sludge remaining in the second SBR is allowed to settle, thereby causing formation of an upper layer of clarified water. Finally, the upper layer of clarified water is decanted. The clarified water obtained contains a low concentration of phosphorus, preferably less than 0,5 mg/l of phosphorus in solution.