| Nitrogen is one of the main factors causing eutrophication.Compared with the traditional nitrification and denitrification process,the partial nitrification-Anammox process has the advantages of low cost and high efficiency.And it is considered as a promising biotechnology for wastewater treatment.However,this process still has many disadvantages,such as the long start-up time and operation instability.In this paper,the fast start-up of partial nitrification-Anammox process were studied in laboratory-scale and pilot-scale reactors.The aim is to provide technological guidance and advice for the promotion and application of partial nitrification-Anammox process in wastewater treatment.(1)The effect of FA(free ammonia)and FNA(free nitrous acid)concentration on the fast start-up of partial nitrification process was investigated.The initial concentration of FA in R1 reactor was 0.02 mg/L.After 28 days operation,the reactor was successful started up.At the end of the operation,the concentrations of FA/FNA in the effluent of R1 reactor were 15.3 mg/L and 0.004 mg/L respectively.And the concentrations of NH4+-N and NO2--N in the effluent were 204.6 mg N/L and 202.0 mg N/L respectively,the ratio of NH4+-N to NO2--N concentration was closed to 1.The nitrite accumulation efficiency reached 93.3%.The initial concentration of FA in R2 reactor was 18.8 mg/L.After 12 days operation,the reactor was successful started up.At the end of the operation,the concentrations of FA/FNA in the effluent of R2 reactor were 8.4 mg/L and 0.002 mg/L respectively.And the concentrations of NH4+-N and NO2--N in the effluent were 112.6 mg N/L and 142.1 mg N/L respectively,the ratio of NH4+-N to NO2--N concentration was closed to 1:1.3.The nitrite accumulation efficiency reached 91.6%.The results show that the high concentration of FA promoted the fast start-up of partial nitrification process in the initial stage.In the later operation,the stability of partial nitrification process is maintained by both of the FA and FNA.(2)The effect of different seed sludges on the fast start-up of partial nitrification-Anammox process was investigated.The R1 reactor was inoculated with 2.0 g MLVSS/L partial nitrification sludge and 0.02 g MLVSS/L Anammox sludge and was successfully started up on the 120th day.The removal efficiency of NH4+-N and TN reached 86.1%and 60.9%respectively.The R2 reactor was inoculated with 2.0 g MLVSS/L activated sludge and 0.02 g MLVSS/L Anammox sludge and was successfully started up on the 80th day.The removal efficiency of NH4+-N and TN reached 82.3%and 52.3%respectively.The results imply that the partial nitrification-Anammox process can be started directly by inoculation of activated sludge rather than partial nitrification sludge,which could avoid the separate domestication of partial nitrification.And the inoculation of low concentration Anammox sludge can promote the fast start-up of partial nitrification-Anammox process.(3)In the pilot-scale reactor,the Sharon-Anammox process was investigated.The Sharon reactor was successfully started on the 20th day and stably operated to 133 day.The concentrations of NH4+-N and NO2--N in the effluent were 225.7 mg/L and 241.2 mg/L respectively.The ratio of NH4+-N to NO2--N concentration in the effluent was stable at 1.The Anammox reactor was inoculated with activated sludge and 0.02 g MLVSS/L Anammox sludge to start up.After 10 days operation,the TN removal efficiency reached 81.3%.At the end of the operation,the concentrations of NH4+-N and NO2--N in the influent reached 140 mg N/L and 180 mg N/L,the TN removal efficiency was stable at 83.8%.At the same time,the abundance of Anammox bacteria in R2 reactor increased from 0 to 6.47%.Finally,R1 and R2 were operated in series to realize the Sharon-Anammox process.The removal efficiency of NH4+-N and TN reached 96.1%and 80.5%respectively.The results show that the fast start-up strategy of partial nitrification and Anammox process can be successfully applied in pilot-scale reactors and stable joint operation. |
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