Study On The Process And Mechanism Of Anaerobic Ammonia Oxidation Process For Wet Treatment Of Ammonia-containing Waste Gas

Ammonia is a colorless and pungent odorous gas produced in many industrial and agricultural production processes,which will lead to great harm to the human body and the environment without proper treatment,such as physiological vomiting,ammonia poisoning,acidification and enrichment of soil and surface water nutrition and so on.Known treatment methods for ammonia gas shares the disadvantages of high cost,secondary pollutants and high energy consumption,which is difficult to achieve balance between treatment efficiency and economic benefit.Anaerobic ammonium oxidation process?anammox?is a new type of efficient and economical biological nitrogen removal technology developed in recent years.In view of this,in this study,the chemical absorption method and wastewater biological denitrification technology will be combined,to reducing operating costs,reducing secondary pollution and reducing energy consumption.First,ammonia gas is aborbed into the aqueous phase under the neutral condition,then iological nitrogen treatment will be performed in a single reactor.Through simultaneous nitrification anaerobic ammonia oxidation denitrification process.The main research contents of this study are as follows:Activated sludge in the anaerobic sewage from two municipal wastewater treatment plant was inoculated to the reactor F and the reactor S,respectively.By controlling the concentration of NH4⁺-N and NO2^--N in the influent,the nitrogen removal efficiency in the two reactors during the start-up and stable operation of the enrichment were investigated.Nitrogen characteristics and sludge activity.Temperature to 35±1 ^oC,the agitator speed in the reactor was 80±10 rpm,the pH was 7.5±0.2,and the dissolved oxygen was 0.After start-up enrichment,the ammonia and nitrogen removal rates of the F and Reactor S were 92.6%and93.9%,the total nitrogen?TN?removal rates were 86.4%and 91.2%,and the sludge activity was 26.3 and 38.2?mol NH₄⁺·gprot^-1·h^-1,respectively.The ratio of ammonium consumption:nitrite consumption:nitrate production were 1:1.24:0.23 and 1:1.27:0.06 respectively.The relative abundance of anammox bacteria accounted for 30.1%?Ca.Kuenenia sp.?and 17.3%?Ca.Kuenenia sp.?at genus level,respectively.It was initially determined that the anammox reactor was successfully started.Ammonia gas was added to the reactor in different strategies,and the effect of ammonia gas addition method on the denitrification characteristics of the reactor was discussed.In the reactor F,ammonia gas was gradually added to the reactor by replacing the ammonium in the wastewater.At this stage,the final removal efficiency of ammonia and TN were 96.1%and98.0%,respectively.The ammonia loading rate in sludge reactor reached 9.63 mmol/d.anammox activity was 58.4?mol NH4⁺·gprot^-1·h^-1,the ratio of ammonium consumption:nitrite consumption:nitrate production was 1:1.30:0.31,N₂O was produced in reactor F during the process which maximum reached 0.42%N.In reactor S,ammonia gas replaced the ammonium in the wastewater at one time.The final removal efficiency of ammonia and TN in this stage are 94.1%and 92.0%,respectively.The final ammonia loading in sludge reactor reached 6.42 mmol/d,anammox activity was 35.2?mol NH₄⁺·gprot^-1·h^-1,the ratio of ammonium consumption:nitrite consumption:nitrate production was 1:1.27:0.19,N₂O produced in the process reached 0.61%N.In this period,the relative abundance of anammox bacteria?Planctomycetales?increased to 68.8%and 37.6%,respectively.The relative abundance of some denitrifying bacteria?such as Pseudomonas,Comamona,Thermomonas,and Thiobacillus,etc.?reached 3.96%and 3.46%.The above results indicate that both ammonia gas introduced methods can treat ammonia-containing waste gas successfully,and they can also promote the growth of anaerobic ammonia oxidizing bacteria and denitrifying bacteria.Gradually increase the external ammonia gas loading?reactor F?has a higher nitrogen removal efficiency and anammox activity compared to the reactor S.The growth rate of denitrifying bacteria under the former method is lower than that of the latter method,which lead to the lower N₂O production.It shows that gradually increasing the way of external ammonia gas is more conducive to the treatment of ammonia-containing waste gas by the anaerobic ammonia oxidation process.The two ways of adding ammonia gas have no obvious effect on the absorption efficiency of ammonia.Oxygen was introduced into the reactor S to setup the SNAD process.The maximum ammonia gas loading was 6.42 mmol·d^-1 and the oxygen loading was 8.09 mmol·d^-1.The comparison found that the removal efficiency of ammonium increased from 94.1%to 97%before and after oxygen,the removal efficiency of TN increased from 92.0%to 99.4%,the activity of anammox bacteria in the reactor was not affected,and the aerobic ammonia oxidizing bacteria?AOB,aerobic ammonia-oxidizing bacteria?activity increased significantly(from very low activity to 36.1?mol NH₄⁺·gprot^-1·h^-1),and the maximum amount of N₂O emissions in the exhaust gas increased to 1.82%N.So far,this research is the first one using the anammox-related process for the biological treatment of ammonia gas,which provides a possible efficient and economical solution for ammonia gas removal.Compared with the nitrification-denitrification process,the SNAD process has lower energy consumption?>30%reduction?,less sludge production?>90%reduction?,smaller greenhouse gas emissions?70-80%reduction?and lower wastewater production?zero wastewater generation?.Therefore,this technology has high application potential and economic market prospects.