Study On The Startup Of Partial Nitrification-anammox Coupling Process And Its Performance In Treating Swine Wastewater

Commonly used methods for removing ammonia nitrogen in water include physical,chemical and biological methods.Physicochemical nitrogen removal technology has the advantages of large capital investment,complicated process and secondary pollution;Compared with traditional nitrogen removal technology,anammox technology can save a lot of additional carbon source consumption and aeration energy consumption,which has attracted more and more attention in recent years.However,the generation cycle of anammox bacteria is long and the start-up of the process is slow;In practical application,nitrite nitrogen as electron acceptor in wastewater is also insufficient;And most of the experiments are still in the laboratory stage.In view of this,this paper first uses granular sludge combined with Fe²⁺to strengthen the start-up and operation of anammox system;Then,the semi nitrosation system matched with anammox was realized by low oxygen stirring and high FA strategy;Finally,the two systems were transferred to a pilot scale mass transfer improved anaerobic baffled reactor to simulate the primary AO effluent of a pig wastewater for advanced nitrogen removal.The main conclusions are as follows:（1）The study of granular sludge combined with Fe²⁺enhanced anammox granular sludge system shows that the inoculation of dewatered granular sludge shortens the time of bacterial autolysis in the initial stage and serves as a crystal nucleus for the growth and enrichment of anammox bacteria,Accelerate the forming time of anammox granular sludge.After a 37-day adaptation period,the metabolic growth of anammox bacteria was stimulated by increasing the influent matrix and the influent Fe²⁺concentration.On the 59th day of the reaction,the average concentration of NH4⁺-N and NO2^--N in the effluent was（1.36±0.07）mg/L,（0.95±0.03）mg/L,the average removal rate is（98.74±0.05）%,（99.22±0.12）%,ΔNH₄⁺-N:ΔNO₂^--N:ΔNO₃^--N is about1:1.17:0.20,light red granular sludge appears at the bottom of the reactor,and the anaerobic ammonia oxidation reactor is successfully started;after the culture matures,the bacteria appear in small coral（or cauliflower）structures and appear in clusters,with filamentous bacteria at the bottom Existence connects the anammox bacteria to the inside,and the dominant genus is Candidatus Kuenenia.The addition of Fe²⁺will increase the activity of ANAMMOX bacteria and have a certain impact on the type and relative abundance of anammox bacteria,but will not change the dominant position of anammox bacteria in the community structure.（2）The research of partial nitrification system matched with ANAMMOX shows that aerobic nitrification sludge is used as inoculation sludge,and the reaction temperature（28±1℃）and continuous low oxygen（DO=0.23～0.49 mg/L）stirring are carried out.,And use the typical cycle test（DO break point and pH ammonia valley point）to optimize the reaction HRT from 10.5 h to 8.5 h;on the 34 th day,the NAR increased to（56.05±3.36）%（>50%）,and the nitrosation was successfully started.And at 77 days to achieve high-efficiency nitrosation operation,the ammonia oxidation rate was stabilized at（77.76±2.37%）,and the NAR was stabilized at（90.73±1.13）%;finally,the high FA（20.71±2.13 mg/L）strategy was used to reduce the effluent NO2--The ratio of N/effluent NH4⁺-N is adjusted to 0.945～1.395（ideal ratio 1～1.32）.At this time,the average ammonia oxidation rate is（69.39±2.25）%,and the average nitrite nitrogen accumulation rate NAR is（80.98±1.23）%,SEM electron microscope morphological analysis shows that the microbial morphology is mainly spherical（0.5～2μm）,and a small number of short rod-shaped（about 1μm）,ellipsoidal（1～2μm）bacteria,and the bacterial structure is very close,and the dominant bacterial group is the AOB bacteria.The semi-nitrosation system started successfully.（3）By controlling each compartment of the anaerobic-semi-nitrosation-anaerobic ammonia oxidation coupling system to a suitable temperature,and performing DO control in compartment II（0.43±0.04 mg/L→0.97±0.05 mg/L）,Adjust the pH of chamber III to 7.6～8.2.In the stage of efficient and stable operation,the volume load of NLR and COD of the reactor are respectively（369.56±0.52）mg N·L^-1·d^-1 and（733±0.39）mg N·L^-1·d^-1.The total NRE is（87.17±0.37）%.The removal of TN is mainly carried out in cell IV,and the remaining TN is mainly composed of NO3^--N produced in cell IV.The denitrification performance of the coupled process is stable and good;the total COD removal rate is（85.78±0.45）%.The COD removal is mainly carried out in cell I,and the contribution rate of cell IV is not low.There is a certain denitrification performance,but it does not affect the cell.The denitrification effect of chamber IV;denitrification at low organic concentration may be able to reduce the NO3^--N to remove the competitive inhibition of anammox by organic matter,and promote the denitrification effect of anammox.Figures:26,Tables:11,References:110.