Study On Commissioning Operation And Enhanced Denitrification And Dephosphorization Of Tianjin Huantang Sewage Treatment Plant

The service area of Tianjin Huantang Wastewater Treatment Plant is the Beitang area,the influent of this project includes industrial wastewater and domestic sewage with a ratio of about 4:6.An inverted A~2/O process was used in this wastewater treatment plant.Considering current economic development,sewage quantity and quality of discharged wastewater in this area,the effect of inverted A~2/O process on nitrogen and phosphorus removal was studied intensively.By analyzing the operation situation since this project initiated and through comparative analysis of effect on nitrogen removal,we concluded that the effect on nitrogen and phosphorus removal can be improved if the project can be operated normally,hoping to provide necessary data support for Tianjin Huantang Wastewater Treatment Plant to improve process.The results show that:(1)Commissioning phase:The commissioning data in the plant showed that the average COD value of the influent was 255 mg/L,and significantly lower than the design value.The average concentration of COD in the effluent was 37.1 mg/L;average concentration of ammonia nitrogen in the influent was 23.4 mg/L,and the average concentration in the effluent was 1.83 mg/L;The average concentration of SS in the influent was 204 mg/L,and average concentration in the effluent was 6.55mg/L.The concentrations of three parameters have met the requirements of first grade A standard in Pollutants Discharge Standards from Municipal Wastewater Treatment Plants(GB18918-2002).Average value of TN in the influent was 34.5 mg/L,and average concentration in the effluent was 17.1 mg/L;Average concentration of TP in the influent was 3.08 mg/L,and average concentration value in the effluent was 0.72mg/L.Concentration of TN,TP could not meet the requirements of first grade A standard.This may be caused by insufficient influent carbon source and imperfect operation during commissioning phase.(2)Strengthening removal of nitrogen and phosphorus:this wastewater treatment plant has strengthened nitrogen and phosphorus removal by adding polymeric ferric sulfate(PFS),polymeric aluminum chloride(PAC),and sodium acetate as carbon source and to improve the process.After this implementation,the average concentration of TN in the effluent was reduced from 17.1 mg/L to 11.2 mg/L.And,the minimum concentration was only 7.55 mg/L;The average concentration in TP in the effluent has decreased from 0.72 mg/L to 0.43 mg/L,and the minimum value was only 0.29mg/L.This shows that the removal rate of TN and TP was obviously improved in Tianjin Huantang Wastewater Treatment Plant after strengthening nitrogen and phosphorus removal,and pollutants concentration can meet the requirements of first grade A standard in Pollutants Discharge Standards from Municipal Wastewater Treatment Plants(GB18918-2002).(3)Temperature has obvious influence on nitrogen and phosphorus removal in A~2/O process.Different microorganisms need different growth temperature,and most microorganisms prefer moderate and high temperature.They are less active at low temperature.In the low temperature period,some measures,including increase of sludge age,dissolved oxygen concentration in the biological tank and MLSS concentration in the system,were taken.By doing so we can strengthen the effect of nitrogen and phosphorus removal at low temperature and ensure that the concentration of main pollutants in Tianjin Huantang Wastewater Treatment Plant can meet the requirements of first grade A standard.