Phosphorus Removal from Supernatants at Low Concentration Using Packed and Fluidized-Bed Reactors

Abstract

The paper deals with a treatment for obtaining phosphorus recovery from anaerobic supernatants with low phosphate concentration (30−50 mg PO4-P/L). The study was carried out at demonstrative scale (inflow up to 2 m3/d), and operative conditions as fluidized or packed bed were investigated. To determine the best operative conditions in the fluidized bed reactor, two upward velocities of 42 and of 64 m/h were performed. Very high phosphorus removal (up to 75%) was observed, and the real performances were similar to those predicted by the mathematical model. Regarding the fluidized bed operative condition into the reactor, the average value of V‘10 was maintained at 110 mL/L throughout the treatment of 234 m3 of anaerobic supernatants. In the second part of the experiment, the polyelectrolyte escape from the dewatering station caused the packing of a great part of the bed, and only a minimum content of the grains remained fluidized (20 000 mg/L). Good performances in phosphorus removal were observed (45−55%)...