An Advanced Denitrification Process Based On Anaerobic Ammonium Oxidation

The discharge of nitrogen-containing wastewater has led to frequent eutrophication of water bodies,which endangers agriculture,fishery,tourism and many other industries,and has become a serious threat to the safety of drinking water and food.The anaerobic ammonium oxidation(anammox)process is an upgrading technology for nitrogen removal from wastewaters.It has been successfully applied to the treatment of high ammonia-containing wastewaters.Although the process has a high nitrogen removal efficiency,it still faces the challenge of pollutant discharge standard for sewage treatment plants.Even if the ammonia nitrogen of discharge water reaches the sewage primary A standard(ammonia nitrogen 5 mg·L-1),it is higher than the surface water class IV water quality standard(ammonia nitrogen 1.5 mg L-1,),higher than the eutrophication index(nitrogen content 0.2-0.3 mg·L-1)of water body.The advanced denitrification process based on anammox remains a blind spot that needs to be investigated.This project started with the current denitrification system based on anammox.The up-to-standard denitrification system based on anammox was successfully established by the addition of r-stretage anaerobic ammonium oxidation bacteria(AnAOB)so as to reach the discharge standard.Then the advanced denitrification system based on anammox was successfully constructed by the enrichment of k-AnAOB so as to increase the discharge standard.Finally the solid carbon source was selected to remove the nitrate from conversion of ammonia and to improve the performance of advanced denitrification system based on anammox.The main results are as follows:1.The up-to-standard denitrification system based on Anammox was successfully established.1)The up-to-standard denitrification system based on Anammox was feasible.With the Anqi reactor as the reaction device and the anammox granular sludge as the inoculum,the up-to-standard denitrification system based on anammox was operated.When the influent concentrations of ammonia nitrogen,nitrite nitrogen and total nitrogen were 91.52-94.3mg L-1,119.45-122.77mg.L-1 and 212.67-214.67mg.L-1,HRT=2h,NLR was 2.55-2.58 kgN m-3·d-1;NRR was 2.06 kgN m·d-1,and ARE,NiRE and NRE were 94.07%,98.99%,77.82%.The ammonia nitrogen in the effluent reached the first-class A emission standard.2)The performance of up-to-standard denitrification system based on Anammox was stable.With the elevation of NLR from 0.58 to 2.58kgN·m-3·d-1,,NRR increased from 0.33kgN·M-3·d-1 to 2.06 kgN·m-3·d-1,and ARE and NiRE were stable at(92.75±2.41)%and(98.89±1.41)%.When the concentrations of ammonia nitrogen,nitrite nitrogen and total nitrogen were 91.52-94.3mg L-1,119.45-122.77mg·L-1 and 212.67-214.67mg·L-1;HRT was 2h;the NLR was at 2.55-2.58 kgN·m-3·d-1;the NRR stayed at 1.90-2.06 kgN·m-3·d-1,and ARE and NiRE stayed at(94.03±0.54)%and(98.98 ±0.08)%.With the elevation of NLR,the performance of up-to-standard denitrification system increased gradually and smoothly;while the performance remained stable at a fixed NLR.3)The up-to-standard denitrification system held a specific microbial community.The biodiversity of seeding sludge was high with Shannon index of 4.03;while the counterpart of up-to-standard denitrification system was low with Shannon index of 3.37.The dominant functional microorganism of seeding sludge was Candidatus Brocadia(45.57%)and Candidatus Kuenenia(7.47%);while the counterpart of up-to-standard denitrification system was Candidatus Brocadia(31.11%)and Candidatus Kuenenia(36.38%).2.The advanced denitrification system based on Anammox was successfully constructed.1)The advanced denitrification system based on Anammox was feasible.Based on the up-to-standard denitrification system,the advanced denitrification system was constructed with the enrichment of k-stratege AnAOB.When the influent concentrations of ammonia nitrogen,nitrite nitrogen and total nitrogen were at 88.33-89.39mg.L-1,120.19-121.29mg L-1,208.52-220.32 mg·L-1;HRT was 4h;NLR was 1.32 kgN.m-3-d-1,the NRR reached 1.09kgN"m-3·d-1;ARE,NiRE and NRE reached 100%,100%and 82.61%,leading to the effluent concentration of ammonia nitrogen better than the Class IV standard of surface water.After the addition of solid carbon source to the advanced denitrification system,the effluent concentration of nitrate nitrogen and total nitrogen decreased below the detection limit of analytic method,leading to the effluent concentration of nitrate nitrogen and total nitrogen better than the Class IV standard of surface water.2)The performance of advanced denitrification system based on Anammox was stable.With the decline of NLR from 2.58kgN·m-3"d-1 to 1.25 kgN·m-3"d-1,the NRR decreased from 2.06 kgN·m-3·d-1 to 1.02 kgN·m-3·d,,and ARE and NiRE stayed stably at(97.24±2.92)%and(99.61±0.50)%.When the influent concentration of ammonia nitrogen,nitrite nitrogen and total nitrogen was at 88.33-89.39mg·L ?,120.19-121.29mg·L-1,208.52-220.32 mg·L-1,HRT was 4h,NLR was 1.25-1.32 kgN·m-3·d-1,the NRR of advanced denitrification system stayed stably at 1.02-1.09kgN"m-3"d-1,ARE,NiRE and NRE stayed stably at 100%,100%and 82.61%.In short,with the decline of NLR,the performance decreased gradually and smoothly;while the performance remained stable at a fixed NLR.3)The performance of advanced denitrification system based on Anammox was competent.Reaction rate,conversion efficiency and effluent concentration are the core performance indices of the advanced denitrification system.With the effluent concentration better than the Class ?standard of surface water,the NRR stayed at 1.06kgN·m-3·d-1,which was far higher than the reported value of 0.3 kgN·m-3·d-1,when the NLR was set at 1.25 kgN·m-3·d-14)The advanced denitrification system held a specific microbial community.The biodiversity of advanced denitrification system was high with Shannon index of 4.27.The dominant functional microorganism was Anaerolineaceae norank?Candidatus Kuenenia and Nitrospira.The increase of Candidatus Kuenenia and Nitrospira was the striking feature.