In order to improve the phosphorus removal effect in the denitrification and phosphorus synchronous removal process by sulfur/sponge iron composite fillers, the phosphorus removal effect by different fillers with the coupling microorganisms was studied to analyze the denitrifying phosphorus removal mechanism of the microbial coupling sulfur/sponge iron composite fillers. The research result showed that the phosphorus removal ratio of sponge iron/sulfur composite fillers was over 95%, which was increased by 30% as compared to only sponge iron filler. In addition, the effluent TP concentration was reduced to less than 0.1 mg·L-1. The analysis of X-ray diffraction(XRD)and total iron concentration indicated that the main phosphorus removal system products which were produced in the corrosion and phosphorus removal process of sponge iron were FeOOH, FeS and Fe4 (PO4)3 (OH)3 deposits and dissolved iron ions; FeS and FeOOH which were the hydrolysis products of Fe2+ and Fe3+ converted PO43- to Fe4(PO4)3(OH)3 by adsorption and deposition so that phosphorus removal could be achieved. After the reactor of microbial coupling sulfur/sponge iron carbon composite fillers became stable, the removal efficiency of TN and TP could reach 90% and more than 83%, respectively; Corrosion of sponge iron and phosphorus removal process could also be promoted by biological iron and H+ that was produced in the sulfur autotrophic denitrification process, the system could realize the combination of "heterotrophic synergy autotrophic" composite denitrification and chemical phosphorus removal, and efficient denitrifying denitrification synchronous phosphorus removal process could be achieved in the urban sewage treatment plant.
Keywords: Fe4(PO4)3(OH)3; FeOOH; FeS; sponge iron/sulfur composite fillers; the removal rate of TP.