Acid treatment enhances phosphorus release and recovery from waste activated sludge: Performances and related mechanisms

Waste activated sludge (WAS) has attracted considerable attention as an excellent material for P recovery from sewage. This study Look concentrated phosphorus removal sludge as objective, and aimed at providing an effective route to promote the transformation of polyphosphate in sludge pellets to dissolved phosphate. After add pH adjustment, total dissolved phosphate at pH 3.0 was 37.3-fold higher than that al natural pH. The P distribution results illustrated that add pH accelerated the degradation of short chain polyphosphate into orthophosphate. Furthermore, cell staining results confirmed that the polyphosphate was sourced from the leakage of intracellular matters. Low field NMR and theology properties analysis were adopted to illustrate that acid pH treatment further improved WAS dewatering peiformances. Accompanied with the reduction of heavy metals in WAS pellets, the acid pH treatment was also beneficial for WAS subsequent treatment or final disposal. Lastly, Fe3+ addition was proposed as favorable P recovery method, and spherical nanometric materials of FePO4 crystal was obtained accordingly. (C) 2020 Elsevier B.V. All rights resented.