Simultaneous Denitrification of Nitrogen and Phosphorus by Pyrite-Sulfur Autotrophic Denitrification Biological Filter
The autotrophic denitration and phosphorus removal technology based on pyrrhotite(PAD)has the ad-vantages of low cost and low sludge production,making it a promising low C/N ratio wastewater treatment meth-od.However,compared to other sulfur-based autotrophic denitration(SAD)processes,PAD has slower kinetics,limiting its engineering application.In this experiment,a self-autotrophic denitration biofilter using pyrrhotite and elemental sulfur as fillers(PSAD-BF)and a self-autotrophic denitration biofilter using pyrrhotite as filler and so-dium sulfide as the driving agent(SAD-BF)were constructed.The nitrate removal load and efficiency of PSAD-BF were higher than that of SAD-BF.The interaction between FeS2 and S0 accelerated the denitration process and maintained acid-base balance,reducing sulfate production.Moreover,phosphate removal was achieved through the formation of FePO4 and Fe3(PO4)2(OH)2.Long-term operation results showed that PSAD-BF achieved a removal efficiency of 90％～100％for total nitrogen and phosphates at a hydraulic retention time(HRT)of 3～12 h,with a maximum denitration rate of 600 mg/(L·d).PSAD-BF is a promising process for iron-sulfur coupled autotroph-ic denitration and phosphorus removal.
pyriteautotrophic denitrificationnitrogen and phosphorus removalsulfur iron cycle
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