Study On Treatment Of Domestic Sewage By SBR Partial-nitritation + ASBR Anammox

The new combined process of partial-nitritation and anaerobic ammonium oxidation?anammox?can save about 50%aeration energy and nearly 100%organic carbon,compared with conventional nitrification/denitrification nitrogen removal process,and sludge yield is low,which has become a research hotspot in recent years.It is used successfully in high temperature and high ammonia nitrogen wastewater.However,it is rarely reported in treating the normal temperature and low substrate sewage to achieve nitrogen and carbon removal by using this combined process.The paper not only optimizes conditions of partial-nitritation and anammox,but also explores the efficiency of the combined process,which provides theoretical guidance and reference for practical engineering applications.?1?The research results of partial-nitritation:?1?Exploring the effect of aeration volume on the stability of partial-nitritation.The anoxic/aerobic mode,the temperature is controlled at 26?,the aeration volume are 100,150and 200L·h^-1,respectively.The effluent NH₄⁺-N concentration is about 30.0 mg·L^-11 after the27th,40th and 37th cycles,respectively;The effluent NO₂^--N concentrations are stable at 30.0mg·L^-1 and the accumulation rate of NO₂^--N is higher than 96.0%after the 33th,42th and39th cycles,respectively,and stable partial-nitritation is achieved,which provides a suitable influent substrate concentration for the anammox.?2?Exploring the effect of temperature on the stability of partial-nitritation.The temperatures are 32?,24?and 12?,the aeration volume is controlled at 100 L·h^-1.The effluent NH₄⁺-N concentrations are stable to 32.94,32.39 and 44.19 mg·L^-11 at the 43th,38th and 53th cycles respectively.The effluent NO₂^--N/NH₄⁺-N are 0.87,1.00 and 0.34,respectively,which achieves stable partial-nitritation at temperatures of 32?and 24?and provides a suitable influent substrate concentration for the anammox.The activity of AOB is inhibited due to low temperature,partial-nitritation is not achieved at temperatures of 12?.?2?The research results of anammox:?1?The effect of HRT on nitrogen and carbon removal of anammox and heterotrophic denitrification are investigated.HRTs are 36h,33h,30h and 27h respectively.The results showed that the nitrogen and carbon removal efficiency are optimum when the HRT is 33h.The effluent concentrations of NH₄⁺-N,NO₂^--N,NO₃^--N and COD are 1.36,0.47,5.76 and49.79mg·L^-1,respectively.The average total nitrogen load rate?TNLR?and total nitrogen removal rate?TNRR?are 0.056 and 0.050 kg·?m³·d?^-1,respectively.The?NO₂^--N/?NH₄⁺-N and?NO₃^--N/?NH₄⁺-N are 1.17 and 0.15,both of which are smaller than the theoretical value of anammox due to the heterotrophic denitrification because of COD in the influent.The effluent concentration of COD gradually decreases with the HRT decreases during the whole experiment,the anammox reaction and heterotrophic denitrification reach synergistic nitrogen and carbon removal.When the HRT decreased,the contribution of ANAMMOX to nitrogen removal decreased,however the contribution of heterotrophic denitrification to nitrogen removal increased gradually.?2?The effect of NO₂^--N/NH₄⁺-N on nitrogen and carbon removal of anammox and heterotrophic denitrification are investigated.The influent of NO₂^--N/NH₄⁺-N are 0.4⁰.6,0.6⁰.8,0.8¹.0,1.0¹.2,1.2¹.4 and 1.4¹.6 respectively.The results showed that the nitrogen and carbon removal efficiency are optimum when the NO₂^--N/NH₄⁺-N is 1.4¹.6,the effluent average concentrations of NH₄⁺-N,NO₂^--N,NO₃^--N and COD are 2.14,1.07,6.52and 30.50mg·L^-1,respectively,which reaches synergistic nitrogen and carbon removal.The?NO₂^--N/?NH₄⁺-N and?NO₃^--N/?NH₄⁺-N are 1.60 and 0.17 respectively.The contribution of anammox to nitrogen removal decreases,however the heterotrophic denitrification to nitrogen removal increases gradually with the decreasing of influent NO₂^--N/NH₄⁺-N.Therefore,there is a certain synergistic and competitive relationship between anammox and heterotrophic denitrification in the system.?3?The effect of influent load on performance recovery of anammox at normal temperature is investigated.The anammox sludge is set aside for one month and then inspects the performance recovery.The temperature is controlled at 24?,and the HRT is 33h.The experiment is divided into four stages.Each stage increases the nitrogen load by increasing the influent NO₂^--N concentration.The results showed that the effluent concentrations of NH₄⁺-N,NO₂^--N,NO₃^--N and COD are 2.11,0.98,6.54 and 34.50 mg·L^-11 respectively in stage III(the influent concentrations of NH₄⁺-N,NO₂^--N,NO₃^--N and COD are 41.69,37.36,2.40 and 85.78¹47.78mg·L^-1,respectively)at the 81th cycles,and the anammox performance is well recovery.?4?The effect of COD/NH₄⁺-N on nitrogen and carbon removal of anammox and heterotrophic denitrification are investigated.The influent of COD/NH₄⁺-N are 2³,3⁵,5⁷and 7⁹,respectively.The results showed that the effluent concentrations of NH₄⁺-N,NO₂^--N,NO₃^--N and COD are 2.46,0.48,7.58 and 35.20mg·L^-11 respectively when the influent of COD/NH₄⁺-N is 3⁵,indicating that the coupling system has good nitrogen and carbon removal effects.Influent COD/NH₄⁺-N is an important factor in affecting the anammox and heterotrophic denitrification.The low concentration of COD can not achieve good synergy between anammox and denitrification,while the excessive concentration of COD inhibites the activity of anammox bacteria but promotes denitrification.?3?The research results of combined process of partial-nitritation and anammox:?1?After achieving stable operation of partial-nitritation and anammox,the efficiency of the combined process for treating domestic sewage is investigated.The effect of the ratio of anoxic to aerobic on partial-nitritation is investigated under the optimal operating conditions(at the temperature of 24?,the aeration volume of 100L·h^-1)of partial-nitritation.The anoxic:aerobic are 3:4,1:2 and 2:5,respectively.The effluent of NO₂^--N/NH₄⁺-N of partial-nitritation are 0.84,1.18 and 1.55 and COD/NH₄⁺-N are about 3.24,3.83 and 4.22,respectively,and stable partial-nitritation is achieved.?2?The effect of different water conditions on nitrogen and carbon removal of anammox and heterotrophic denitrification are investigated under the optimal operating conditions?HRT is 33h,NO₂^--N/NH₄⁺-N is 1.4¹.6,COD/NH₄⁺-N is 3⁵?of anammox.The results showed that the effluent average concentrations of NH₄⁺-N,NO₂^--N,NO₃^--N and COD are 2.79,0.49,4.24 and 35.79 mg·L^-11 when the influent of NO₂^--N/NH₄⁺-N and COD/NH₄⁺-N are 1.55 and4.22,respectively.The anammox and heterotrophic denitrification reach synergistic nitrogen and carbon removal.