| abstract |
A method and apparatus is provided for treating wastewater to remove nitrogen, carbon, and phosphorus simultaneously while simultaneously recovering energy in the form of methane and carbon dioxide. A stream containing ammonia is introduced into a pretreatment tank that produces excess sludge, biogas, and a pretreated stream. The pretreated stream has at least 45% less carbon than the ammonia-containing stream. The pretreated stream is then introduced into a low oxygen tank that promotes the release of phosphorus and the fermentation of particulate and dissolved organic materials. The mixture is transferred to an aeration tank with a low dissolved oxygen concentration, thereby promoting the growth of phosphorus-releasing bacteria and finally recycled to the low oxygen tank as a return activated sludge. In the aeration tank, simultaneous nitrification, denitrification, and phosphorus release occur. In the membrane tank, the treated effluent is separated from the activated sludge in the membrane tank. [Selection] Figure 6 |