| Anaerobic ammonium oxidation（Anammox）process is a novel,autotrophic and biological nitrogen removal technology with great economical and ecological benefits,which has a wide nitrogen removal potential in the treatment of high-ammonia and low-carbon/total nitrogen wastewater.However,the difficulties of extremely slow growth rate and susceptibility to the organic matters and dissolved oxygen of Anammox bacteria limited its industrial application.The study intended to obtain the Anammox bacteria enrichment cultures rapidly at room temperature by two steps:Anammox bacteria was pre-enriched by starting up the OLAND process and cultivated from Anammox sludge.The Anammox process was successfully started up in a short time by optimizing the operating conditions,adding mixed carriers and so on.Fixed bed biofilm reactor（FBR）filled with honeycomb-like carriers was inoculated with normal activated sludge to start up the OLAND process with synthetic wastewater at room temperature.The temperature was controlled at the range of 23℃26℃,the hydraulic retention time（HRT）was fixed at 2 d,the dissolved oxygen（DO）of the influent was kept at the range of 0.5 mg/L1.0 mg/L,the initial concentration of influent NH4+-N was kept at 50 mg/L.The results demonstrated that Anammox activity appeared on day 31;the max removal efficiencies of NH4+-N and TN were 89.54%and 95.45%respectively and the max total nitrogen removal rate reached 38.82 g/（m3·d）.The seccefull start-up of the OLAND process can improve Anammox start-up performance,meet the nitrogen removal demand of municipal sewage,and it has wide application prospect in the treatment of low ammonia nitrogen and low COD wastewater.Anammox was started up in a FBR filled with honeycomb-like and non-woven mixed carriers by inoculating the oxygen-limited autotrophic nitrification/denitrification（OLAND）sludge at room temperature.The temperature was at the range of 15℃25℃,the DO of the influent was kept below detection limit（0.1 mg/L）,HRT was shorted from 2 d to 1.5 d,influent concentrations of NH4+-N and NO2--N were stepwise increased from 60 mg/L and30 mg/L to 320 mg/L and 260 mg/L respectively.The results showed that the Anammox activity occurred on day 1,resulting from the synchronized removal of NO2--N and NH4+-N,the max removal rate of total nitrogen reached 336.44 g/（m3·d）on day 101.The typical cauliflower-shaped structure was observed in the mature sludge with scanning electron microscopy,and there were no filamentous and rod-shaped flora bacteria.According to the phylogenetic analysis,Candidatus Kuenenia stuttgartiensis and Candidatus Brocadia flulgida were detected in the mature biofilm and constituted 70%and 30%of Anammox bacteria,respectively.Candidatus Kuenenia stuttgartiensis played a key role in the reactor.During the start-up of the OLAND process and the Anammox process,the DO in FBR was changed by changing the aeration amount of N2,the inflow loading was adjusted by shortening the HRT and increasing the influent concentrations of NH4+-N and NO2--N.The influent concentrations were adjusted according to the bacteria community characteristics at different stages,the adjustment can effectively avoid the self-inhibition caused by high concentration ammonia and nitrite.DO and pH was adjusted by combination of aerating and flushing of N2/CO2,and the CO2 provided carbon source for the growth of Anammox bacteria.Hydrochloric acid was added to the reactor when pH needed.The synthetic wastewater must be updated to shorten the suppressed time when the pH and the influent matrix inhibited the activity of Anammox. |
