The Initial Study On Water Treatment From Recirculating Aquaculture System By Anaerobic Ammonium Oxidation

With the more serious environmental problems and food security, the traditionalaquiculture model already do not accord with the requirement of sustainabledevelopment. Circulation aquaculture system with environment friendly is one ofimportant mode of aquaculture. It is a key part to remove the ammonia and nitrite fromsewage in the fish farming. Anaerobic Ammonium Oxidation (ANAMMOX) is a newprocess that has been found in recent years. More and more scholars are begining tostudy the anaerobic ammonia oxidation process which will be the mainstream of thedevelopment of biological denitrification of wastewater in the future. But theapplication of the anaerobic ammonia oxidation process is restricted. To set a goodfoundation for its further research，the paper gives some examples in application ofanaerobic ammonium oxidation process and problems appeared in application。This teststart successfully ANAMMOX reactor and discusses the feasibility of anaerobicsequencing batch reactor (ASBR) treatment of the sewage in circulating aquaculturesystems.The start-up of ANAMMOX process in a4L ASBR reactor seeding with activatedsludge from a municipal sewage treatment plant was investigated. The start-up processis divided into the early stage（1-17d）, displayed active stage（18-51d）, strengthenedactive stage（52-85d） and stable stage（86-117d）, The results demonstrated thatANAMMOX process was achieved successfully with high removal efficiencies of NH4+-N、NO2--N and TN up to100%、100%and78%after117day’s of operation andacclimation. The average ratio of removed ammonia, removed nitrite and produced nitrate was1∶1.31∶0.24at the stable stage of the process. The effluent pH keptaround7.9-8.5. The sludge of brown was found from the reactor. At the117d of theexperiment, the sludge was observed by scanning electron microscope for analysis oftheir surface morphology. Results showed that grain-sludge appeared irregular ellipsoidand size of less than1μm. PCR amplification by using specific primer（Pla46rc/Amx820）was performed and received800bp band.To study of TOC influence on the performance of the ASBR reactor，remain theaforementioned reaction conditions(Influent TN loading:0.24kg/(m3·d)，NH4+-N:80mg/L, NO2-N:105mg/L) by adding different concentration of glucose continuously（each gradient running3cycles）on the basis of the above launchedASBR. The resultsshowed that: low concentration of organic matter（TOC mass concentration<150mg/L）could promote ANAMMOX ability of the reactor. When TOC mass concentrationachieved150mg/L, TOC removal rate was70%and TN removal rate was96%. Thetest indicates that the synergism of denitrification and ANAMMOX are achieved. Itcould ’t satisfy aquaculture when effluent NH4+-N had reached3mg/L after TOC massconcentration achieved210mg/L. The disturbance of TOC to the performance could berecovered within a period as long as the organic matter was removed.The further study had tested the performance of ASBR ANAMMOX reactor bychanging the ratio of influent concentration of NO2--N/NH4+-N as based on thesuccessful recovery of ASBR reactor. The results show that there have no effect onremoving NH4+-N and NO2--N while having great influence on TN by reducinginfluent concentration of NO2--N. NH4+-N was completely removed under two bacteria(AOB and ANAMMOX). When the ratio of influent concentration of NO2--N/NH4+-N reduced to0.3, the removal rate of TN was below50%and reactor was suffered tosevere impact. But the reactor could be recovered by adding the nitrite again. Test theperformance of ASBR ANAMMOX reactor by reducing the loading of reactor asmaintaining the concentration of influent nitrite and ammonia. Results show thatremoval efficiency of NO2--N and NH4+-N was stable as high as100%in the process of influent NH4+-N decreased gradually, but the produced nitrate increased gradually.When influent NH4+-N reduced to10mg/L, the removal rate of TN reduced to6.5%andthe system was going to be collapsed. It’s showed that reactor will appear" hunger"phenomenon and could not remove nitrogen normally if reduced influent loadinggreatly long-term at high loading operation of ANAMMOX reactor. The removal rate ofTN immediately rose after adding some organic matter (glucose) to the influent water oflower ammonia (<10mg/L) which is beneficial for the reactor removing nitrogen. Whenthe TOC concentration was90mg/L, the removal rate of TN reached90%, whichshowed the reactor could effectively deal with simulation of aquaculture waste water.So it can make the theory basis for the application of ANAMMOX in aquaculture.