| Water pollution is one of the most serious environmental problems in China. In recentyears, the contradiction between economic growth and people’s increasing requirement ofsewage treatment has been increasingly intensified, which makes people’s desire to developa new wastewater treatment technology of lower energy consumption and higherdenitrification efficiency more urgent. The combined two-stage BAF and anaerobicbiofilter were used to treat the simulated industrial wastewater with low C/N. Shortcutnitrification and autotrophic denitrification had achieved by controlling the operationparameters during the tests, meanwhile, the influences of operation parameters werediscussed on the nitrification and denitrification. Microbial community diversity waspreliminarily analysed using PCR-DGGE technology in order to explore the mechanism ofnitrogen removal in the combined reactor. Accordingly, the main research achievementswere as follows:(1) The BAF C and N column were started up using composite biofilm methodincluding activated sludge acclimatization, aeration biofilm and continuous flow culture.The results showed that ceramsite and natural zeolite had good film-forming effect andwere adhered to different biofilms on their surfaces by means of scanning electronmicroscopy (SEM) and NH4+-N adsorption kinetics experiment analysis. NH4+-Nadsorption capacity of natural zeolite before and after film-forming is stronger than that ofceramic.(2) Biological aerated filters would have restarted in anchorage for a month. It showedthat the recovery of BAF N column was more difficult than BAF C column, which tookabout half one month, and the effluent NO3--N concentration was still high, NO2--Naccumulation rate was only10.3%as a result of fruitless nitrosification effect after about40days’ restarting. The reason was that external conditions had a little influence onheterotrophic baceria, so the recovery of carbonization system was relatively easier,whereas nitrate baceria has the higher adaptability than nitrite oxidizing bacteria,nitrification system easily affected by environmental change has slowly to normal. (3) The experiment showed that water temperature was the main factor affectingshortcut nitrification, which was more than DO and pH. The results showed that nitriteaccumulation achieved at6～10℃and≥22℃, but failed at13～18.2℃. DO and pH werethe important factors, so the optimal DO concentration range of BAF N was from2.43to4.75mg/L at6～10℃, the optimal influent pH range was7～9at25～26.8℃. FA and FNAhave the inhibitory effect on nitrite oxidizing bacteria. Proper backwashing was favorablefor nitrite accumulation.The backwashing effect was investigated as follows:5.31L/(m2·s)of air flow rate and0.88L/(m2·s) of water flow rate. The results showed that NH4+-N totalremoval rate increased to80%afer10h of backwashing and the highest nitriteaccumulation rate was82.5%afer17h, which was significantly higher than74.5%ofpre-bachwashing.(4) ANAMMOX reactor was successfully started up using intermittent and continuousinflow feeding method at25～35℃afer a total of90days.The effects of influent pH, TNvolume loading and N substrate ratio were respectively discussed on anammoxdenitrification efficiency. It showed that the average NO2--N removal rate was61.7%if pHwas7.5～9.0. When TN volume loading was0.19～1.23kg TN/(m3·d), the average TN andNO2--N removal rate were respectively about51%and61%. Additionally, the highest TNand NO2--N removal rate were severally62.2%and54%when NH4+-N：NO2--N：NO3--Nwas1:1.3:0.4.(5) The various protozoan and metazoan species of BAF C and N column were foundby using the optical microscope to observe biofilm microorganisms, the microbial specieswere different along the flow direction from top to bottom, from which the biomass andbio-activities of nitric bacteria, nitrobacteria and heterotrophic bacteria were not the same.(6) Bacterial diversities of the BAF C and N column and anaerobic biofilter wereanalyzed by using PCR-DGGE technology. According to the characteristic bands of DGGEpattern in the different locations, it showed that the dominant species in the three reactorswere different. Along the flow direction from top to bottom, both DGGE fingerprint bandsand species diversity index H of the BAF C column decreased gradually indicatinghydraulic conditions had great influences on the heterotrophic bacteria, but similar phenomenon did not appear in the BAF N column, which indicated the nitrifying bacteriapopulation was very capable resistance hydraulic loading. The worst bacterial diversityanalysis results displayed that anaerobic bacteria gradually showed specificity in anaerobicbiofilter. |
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