Description:
Existing techniques to recover phosphorus from urban sewage in the form of vivianite face difficulties in separating the crystals from the sludge. The present work proposes a new process for the efficient online recovery of phosphorus by growing vivianite crystals through fluidized bed crystallization (FBC) from biofilm-enriched phosphorus solution (up to 179.5 mg·L −1 ). The impact of process parameters on the phosphors recovery (PR), the crystallization ratio (CR), and the crystal size were examined. Under optimized conditions, i.e., 140 mg·L −1 phosphorus in the raw water, 15 m/h liquid up-flow velocity, and 5 h hydraulic retention time, a single batch of the FBC reaction could attain a high PR of 95.30% and a high CR of 88.23%. After seven consecutive batches of the FBC reaction, large vivianite crystals (d 50 = 270.52 mm) could be recovered. The identity of the collected vivianite crystals was verified by X-ray diffraction (XRD), scanning electron microscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). The proposed process shows very good potential as it can turn urban sewage into a valuable resource from which phosphorus can be efficiently recycled