| The novel combined process of shortcut nitrification-anaerobic ammonia oxidation(anammox)can save aeration energy,shorten reaction time,be not limited by carbon sources,and reduce sludge volume,etc.It is used successfully in high-ammonia nitrogen wastewater such as landfill leachate and sludge nitrification supernatant.However,it is very limited in low-ammonia wastewater treatment plants.The paper not only optimizes conditions of the shortcut nitrification and anammox reaction,but also studies the denitrification performance of the combined process,which provides a theoretical reference for the practical application of the project.The major research results of shortcut nitrification:(1)Combining the effect of alternating aerobic/anoxic and anoxic/aerobic with inoculation sludge on shortcut nitrification.The temperature is controlled at 25±0.5°C.The influent NH4+-N and COD average concentrations are 65.59 mg/L and 219.10 mg/L,respectively.(1)Under the condition that the sludge does not have the full nitrification activity,the alternate anoxic / aerobic mode(4 cycles alternately anoxic: aerobic = 30 min: 30 min)runs for 70 cycles,the ammonia nitrogen removal rate(ARE)and COD removal rate are 98.67% and 79.55%,respectively.The nitrite accumulation rate(Ni AR)reaches 98.44%,and a stable shortcut nitrification is successfully achieved.(2)Under the condition of alternate aerobic/anoxic,the sludge has full nitrification activity.The alternate aerobic/anoxic mode(5 cycles alternately aerobic: anoxic= 30 min: 30 min)runs for 64 cycles,the effluent NO2--N concentration is 19.04mg/L and the Ni AR reaches 99.21%.The shortcut nitrification is successfully achieved.(3)Under the condition of alternate aerobic/anoxic,the sludge has no nitrification activity.The alternate aerobic/anoxic mode(4 cycles alternately aerobic: anoxic = 30 min: 30 min)runs for 58 cycles,the removal rates of ARE and COD are 96.25% and 77.43%,respectively,and Ni AR reaches 97.95%.(2)Exploring the effect of intermittent aeration on shortcut nitrification.The temperature is controlled at 25±0.5°C.The intermittent aeration ratios of aerobic to anoxic are 30 min: 30 min,40 min: 20 min,and 30 min: 60 min,respectively.After operating for 64,75,and 82 cycles,respectively,the effluent NO2--N concentrations are 19.04,19.42 and 17.42 mg/L,respectively,and the Ni AR are as high as 99.21%,95.47% and 99.75%,respectively,all of which successfully achieve stable shortcut nitrification.(3)Exploring the effect of temperature on shortcut nitrification in intermittent aeration mode.The temperatures are controlled at 18°C,25°C and 30°C,and the ratio of aerobic/anoxic time is 30 min/30 min.After operating for 90,70 and 61 cycles,the effluent NH4+-N concentrations are 1.28,0.98 and 0.68mg/L,respectively.AREs are as high as 99.57%,98.32% and 98.94%;The effluent NO2--N concentrations are 20.18,19.04 and 20.57mg/L;Ni AR reaches 99.58%,99.21% and 95.92%,respectively,and stable shortcut nitrification is successfully achieved at all three temperatures.(4)Exploring the effect of aeration volume on short-cut nitrification recovery in intermittent aeration mode.The shortcut nitrification sludge is set aside for 2 months and then inspects the activity recovery.And the actual domestic sewage is treated at the temperature of 25°C with the ratio of alternate aerobic/anoxic time of 30 min/30 min,and the controlled aeration volume are 120,100,80 and 60 L/h,respectively.The effluent NH4+-N concentrations are stable below 5 mg/L after the 12 th,18th,21 st and 21 st cycles,respectively.The effluent NO2--N concentrations are 20.83,22.81,21.50 and 20.73 mg/L,respectively,which occur in the 30 th,35th,38 th and 42 nd cycles,respectively.Ni AR are higher than 99%.The recovery of shortcut nitrification is achieved successfully in all four types of aeration.The major research results of anammox in stable operation phase:After starting up successfully anammox reaction,the effects of temperature and the influent substrate ratio(NO2--N/NH4+-N)on anammox reaction are explored.Anaerobic sequencing batch reactor(ASBR)is used to treat simulated domestic waste water.The influent p H is controlled at 7.2±0.2.(1)The gradual cooling strategy(30-25-20-15°C)is used to explore performance of anammox.When the temperature is reduced to 15 °C,ARE decreases to about 60% at the 36 th cycle,therefore it can remove nitrogen in some extent.(2)At the temperature of 30°C,the influent substrate ratios(NO2--N/NH4+-N)are 0.9,1.1,1.3,1.4,1.5 and 1.6,respectively.When the influent NO2--N/NH4+-N is 1.4,the effluent NH4+-N and NO2--N concentrations are 0.81 mg/L and 1.52 mg/L at the 28 th cycle.The actual ?NO2--N /?NH4+-N is about 1.37,?NO3--N /?NH4+-N is maintained about 0.25-0.28,both of which are basically closed to the theoretical values.The major research results of combined process of shortcut nitrification-anammox:The combined process of SBR+ASBR is used to treat the actual domestic sewage,and explore the performance of nitrogen removal of combined process on complete shortcut nitrification-anammox.Under the optimal operating conditions(Intermittent aeration alternating aerobic: Anoxic = 30min: 30 min,at the temperature of 25°C,the aeration volume of 80 L/h)on shortcut nitrification,the best mode of operation is 6 times aerobic condition and 3 times Anoxic condition.The effluent NO2--N concentration is maintained at about 43 mg/L.The ASBR reactor is used at a temperature of 30°C,The mixed sewage includes the domestic sewage water and shortcut nitrification effluent water which the ratio of them is 3:5.The artificial water is gradually replaced by mixed sewage,and then the effect of water quality is explored on anammox.The artificial water is replaced completely by the mixed sewage at the 43 rd cycle.The good removal nitrogen is achieved.When the ratios of domestic sewage water to shortcut nitrification effluent water are 3:5,2:3 and 2:4,respectively and the influent NO2--N/NH4+-N is basically maintained at 0.95-1.58.The ?NO2--N /?NH4+-N is slightly higher than the theoretical value of anammox(1.32),and ?NO3--N /?NH4+-N is lower than the theoretical value(0.26).The combined process achieves nitrogen removal efficiently. |
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