The distribution of phosphorus forms in dewatered sludge with three classification analysis methods

Determining the distribution of phosphorus forms in dewatered sludge is crucial, as it directly impacts the choice and effectiveness of recovery strategies. Analyses using the standards measurements and testing (SMT) method, soluble/insoluble fractionation and extracellular polymeric substances (EPS) /EPS residue extraction, revealed that sludge characteristics significantly influenced phosphorus speciation and content. Inorganic phosphorus (IP) was the dominant form in dewatered sludge, primarily regulated by the levels of Al, Fe, and Ca, while dissolved orthophosphate (ortho-P) constituted only 1% of the total phosphorus (TP). Notably, phosphorus exhibited a distinct distribution pattern between EPS and EPS residues: EPS comprised only 2.09% of TP, 74.19% of which was organic phosphorus (OP), whereas EPS residues contained 93.26% of TP, with a much lower OP proportion (15.04%).