Different Carbon Sources And Adding Methods To Strengthen Biochemical Pools And Denitrifying Performance Of Deep Bed Denitrifying Filter

At present,most domestic and foreign sewage treatment plants mainly adopt biological denitrification process in denitrification process.This method must use the easily degradable organic matter in the influent as the electron donor.When the influent carbon nitrogen ratio is low,the low organic matter content will affect the denitrification process of biological nitrogen removal.At this time,it is necessary to add external carbon sources to improve the biological nitrogen removal efficiency.This paper studies the types and locations of external carbon sources,determines the denitrification effect and economic cost of different types of carbon sources and dosing methods,improves the external carbon source dosing methods of biochemical tank and deep bed denitrification filter,determines the best carbon source dosing methods and operating parameters,and calculates the costs of different dosing methods.The main research results are as follows:(1)In the experimental study of the types of additional carbon sources,the average denitrification efficiency of sodium acetate,citric acid,ethanol and glucose as a single carbon source was studied.Among them,sodium acetate had the best denitrification efficiency,which was 86.12%.At the same time,the mixed carbon source of sodium acetate and citric acid had the best nitrogen removal efficiency,which was 89.49%.The denitrification capacity of mixed carbon source is stronger than that of single carbon source,and the removal effect and law of total nitrogen by different carbon sources are similar to that of nitrate nitrogen.(2)The denitrification factors of biochemical tank based on improved A/A/O process and their effects on denitrification were studied.The results show that low dissolved oxygen and high reflux ratio in aerobic zone will achieve better carbon source utilization efficiency.At this time,the total nitrogen removal rate of the additional carbon source reached 90.21%,and the chemical oxygen demand of the effluent was not affected.At the same time,stopping adding after 15 days of continuous adding could maintain high-efficiency nitrogen removal for 4 days,so as to reduce the use of carbon source.(3)By studying and analyzing the nitrogen removal efficiency and carbon source dosage of the front and back feedback carbon source dosing system based on the elimi nite deep bed denitrification filter,the total nitrogen removal rate reached 65.02% when sodium acetate was used as the filter plus carbon supplement.Optimization is proposed for the current carbon source dosing mode.Under the set conditions,reducing the dosage can still maintain the high nitrogen removal efficiency for about 12 hours,reducing the carbon source dosage of the deep bed filter.The research work of this paper shows that when the dissolved oxygen in the aerobic section of the biochemical tank is 2.5 mg/l and the internal reflux ratio is 200%,it has the best denitrification efficiency;The deep bed denitrification filter has the best denitrification efficiency when the hydraulic retention time is 100 minutes.By optimizing the operating conditions,the carbon source dosing of the biochemical tank and the deep bed denitrification filter can be reduced without affecting the denitrification effect,effectively reducing the reagent cost and the cost of per ton of water treatment.