Start-up And Treatment Of Denitrification Performance Of Flue Gas Desulphurization And Denitrification Tail In Anamox-ASBR

The flue gas desulphurization and denitrification tail gas produced by a thermal power plant refers to the residual waste liquid that is left during the alkaline wet desulfurization process after the pre-denitrification of flue gas（SCR method）,and has high ammonia nitrogen and high salinity（CI,SO42-concentration）and low B/C features.The traditional biochemical denitrification method is still very difficult for the treatment of desulfurization and denitrification tailings.Anammox is a resource-saving and environment-friendly biological denitrification pathway.However,the growth of anammox bacteria is slow,and the time required for enrichment culture is longer.This paper studies the start-up of pilot-scale experiments of the Anammox-ASBR process and the study of nitrogen removal performance.The following research results have been obtained:Anaerobic ammonia-oxidizing bacteria were studied for enrichment under different inoculation sludge conditions.Two sets of pilot-scale anaerobic sequencing batch reactors（ASBR）（R1 and R2,effective volume 530L）were used to Oxidation ditch-and-oxygen sludge and sludge from A/A/O anaerobic zone were inoculated.Anammox initiation and its denitrification coupled denitrification characteristics were investigated.At the same time,the structure of bacteria was analyzed.The results showed that under the conditions of temperature 35±1°C,influent p H value 7.5±0.2,and anaerobic time 20 h,R1 and R2 were operated for 180 d and 160 d,respectively,and the successful startup of Anammox could be achieved.In the stable operation stage,the nitrogen removal rates of the two groups of reactors were 0.3 kg·m-3·d-1 and 0.35 kg·m-3·d-1,respectively,but R2 had high nitrogen removal performance（up to 0.52 kg·m-3d-1）.Anammox was the dominant reaction in both reactors,but both denitrification and denitrification occurred at the same time,making the effluent total nitrogen concentration lower than 31 mg·L-1,and the TN removal rates were 91% and 92%,respectively.The sludge in both R1 and R2 was light red granular,and the main genus was Candidatus Brocadia.The impact resistance and recovery characteristics of desulfurization and denitrification tailings in thermal power plant with Anamox-ASBR were studied.The results showed that the ASBR reactor（530 L）started from the oxygen-segmented sludge inoculated with the oxidation ditch process was used.The desulfurization and denitrification tailings suppression and strain recovery stages can remove inhibitory factors,reduce the influent substrate concentration,and properly adjust the influent p H.After 93 days of operation,the removal rates of NH4+-N and NO2--N increase from 0% to near 100%,the activity of anammox bacteria was restored.By gradually increasing the ratio of different desulfurization and denitrification tails（30%,70%,100%）,the high-efficiency denitrification of desulfurization and denitrification tailings by the pilot SAD-ASBR is achieved,and the concentration of effluent NH4+-N and NO2--N is stably maintained near 0 mg·L-1.By fitting the three modified models,it is concluded that the modified Logistic model is more suitable for the NRR recovery process after desulfurization wastewater tail water shock.The NRR recovery delay time λ is 17.777 cycles and R2 is 0.92948.The effects of NH₄⁺-N,NO₂^--N and NO₃^--N concentrations on the denitrification performance of Anammox-ASBR were studied.The results showed that the concentration of influent nitrate nitrogen had little effect on anaerobic ammonia oxidation,especially in the low concentration range（<60 mg·L-1）,which did not affect the anaerobic ammonia oxidation process.When the nitrate concentration of influent nitrate is more than 80mg·L-1,the denitrifying bacteria do not have sufficient COD for denitrification,and the total nitrogen removal rate gradually decreases.The nitrate concentration in the influent water is to 81% at 20 mg·L-1 gradually decreased to 48% at 120 mg·L-1.NH4+-N,NO2--N concentration increase in the early stage of concentration increase will result in the denitrification performance of the reactor is weakened,the ammonia concentration in the effluent reaches 18.4 mg·L-1,the total nitrogen removal rate decreases to 82.1%,but with stable operation In the reactor,the anammox bacteria group will gradually increase the treatment efficiency,and the effluent quality will gradually increase.After the influent ammonia nitrogen reached 220 mg·L-1,the reactor was still able to adapt to the higher ammonia nitrogen influent,and the effluent ammonia nitrogen gradually decreased and finally remained at 2mg/L.The modified Logistic model was used to simulate the typical cycle kinetics of anaerobic ammonia oxidation reactor under high ammonia nitrogen concentration（220 mg·L-1）.It was found that R2=0.9907.NREmax is 91.1%,Rmax is 6.89 %/h,and λ is 3h.