[Distribution of phosphorus fractions and bio-available phosphorus forms and their relationships in sewage sludge].

To investigate the potential bioavailability and mobility of phosphorus (P) in sewage sludge, the Standards, Measurements and Testing (SMT) programme was employed to characterize the distribution of P in sewage sludge from different treatment stage of Jiangxinzhou WWTP. The results showed that the inorganic phosphorus (IP), accounting for 61%, was the predominant fraction of total phosphorus (TP), while the organic phosphorus (OP) in TP was only 15% to 35%. And the IP mainly distributed in the non-apatite inorganic phosphorus (NAIP) fraction, accounting for more than 60%. It suggested the high potential bioavailability and mobility of P in sewage sludge. The significant positive correlations between the contents of TP and the NAIP + OP indicated that the determination of TP could be used to estimate the potential bioavailability of P in sewage sludge. The correlations between the P fractions and the physical-chemical characteristics suggested that the LOI and pH would influence significantly on the potential mobility of P in sewage sludge.