| In recent years, the standard of sewage treatment plant effluent will be improving, advanced wastewater treatment is very important. Therefore, heterotrophic denitrifying and sulfur autotrophic denitrification is used to do some research on advanced nitrogen removal. This paper examines the performance and cost of advanced nitrogen removal by using the method of heterotrophic denitrification and it focuses on the performance and cost of advanced nitrogen removal by using the method of the sulfur autotrophic denitrification. Furthermore, it is necessary to explore the ability of advanced phosphorus removal by adding elemental iron to the sulfur and limestone autotrophic denitrification systems.When the influent NO3--N concentration was 12.5 mg/L, sodium acetate as external carbon source, the carbon and nitrogen ratio was 4.4, the hydraulic retention time was 0.5 h, the effluent concentration of NO3--N and NO2--N was less than 0.20 mg/L. But in condition equivalent ratio, namely C/N = 2.86, HRT = 4 h, the effluent concentration of NO3--N was 3.50 mg/L. It was likely to cause the COD of the effluent exceeded by using the method of heterotrophic denitrification, this will lead to residual COD that affecting the water quality.The method of sulfur autotrophic denitrification also had the advantages of good effect and faster rate to reach the aim of advanced nitrogen removal. When the influent NO3--N concentration was 12.5 mg/L, HRT=1 h, the effluent concentration of NO3--N and NO2--N was less than 0.20 mg/L, the removing load and influent nitrate load of nitrate were substantially equal. In the sulfur autotrophic denitrification system, the effluent nitrate concentration was 1.2 mg/L at 30 cm in front of the packed bed, the removal rate reaching 91%. Sulfur autotrophic denitrification also had the advantages of TP and NH4 +-N removal. The effluent of sulfate concentration will not exceeded, the effluent sulfate concentration is about 120 mg / L, which was lower than the national standard value of 250 mg / L.If the secondary effluent of NO3--N concentration was 12.5 mg/L, it achieved the standard of class IV using the method of heterotrophic denitrification, sodium acetate will cost 0.146yuan/ton; by using sulfur autotrophic denitrification, sulfur and calcium carbonate particles will cost 0.046yuan/ton.Meanwhile, the effect of advanced phosphorus removal will be very obvious in sulfur autotrophic denitrification system after the admixture of iron, When the influent NO3--N concentration was 12.5 mg/L, the TP concentration was 1 mg/L,HRT=1 h, the mean effluent concentration of TP was 0.10 mg/L after the admixture of iron; it also had some role in promoting denitrification when adding some iron in the Sulfur autotrophic denitrification systems, the Semi-order reaction rate constant respectively was 6.56 and 10.03 mg1/2/（L1/2·h） before and after mixing elemental iron. |
