Abstract
Three kinds of seeding sludge, i,e, conventional activated sludge, anaerobic granularsludge and the nitrifying activated sludge from the nitritation reactor treating agedleachates were evaluated in batch mode to screen the optimized inoculum for the rapidstart-up of ANAMMOX reactor. The feasibility of the ANAMMOX process for thetreatment of aged leachates was also investigated in a modified upflow anaerobic sludgeblanket (UASB, 0,05 m\ The batch experiments revealed that the nitrifying activatedsludge from the nitritation reactor could respectively achieve the NRR (nitrogenremoval rate) of 0,0365 kg N/(m3,d) and the ARR (ammonium removal rate) of 0,013kg N/(m3.d) on day 12, which were greatly higher than those of the other two testedsludge samples, The mixture of the aforementioned nitrifying activated sludge andanaerobic granular sludge was established as an effective inoculum for the prompt startup of ANAMMOX reactor. The maximum total nitrogen removal rate of 0,826 kgN/(m3,d) could be obtained for the treatment of "old" leachates under NLR (nitrogenloading rate) of 1.028 kg N/(m3.d), It is concluded that the N-removal performance ofANAMMOX process is still to be improved for actual engineering application to agedlandfill leachates,
Highlights
Leachate from "old" landfills are often rich in ammonium nitrogen and deficient in biodegradable carbon source
3 RESULTS 3.1 Screening of seeding sludge As for the nitrifying activated sludge, the simultaneous removal of ammonium and nitrite and nitrate was clearly observed on day 12, indicating occurrence of the anaerobic ammonium oxidation (ANAMMOX) reaction.The nitrogen removal rate (NRR) and ammonium removal rate (ARR) were respectively 0.0405 kgN/(m3.d) and 0.016 kgN/(m3.d) on day 14.During 14 days of operation, the ANAMMOX activity of the activated sludge could be neglected(ARR was 0.0053 kg N/(111e3.d))
Taking into account the best ANAMMOX capacity of the nitrifying activated sludge and easy granulation, the mixture of nitrifying activated sludge and anaerobic granular sludge was used as inoculum for following the ANAMMOX reactor experiments. 3.2 Start-up of the ANAMMOX reactor The ANNAMOX reactor was started-up by inoculating 0.014 1113 of the nitrifying activated sludge from the nitritation reactor and 0.021 me3 of the aforementioned anaerobic granular sludge
Summary
Leachate from "old" landfills are often rich in ammonium nitrogen and deficient in biodegradable carbon source. The feasibility of stable nitrite accumulation from aged leachates has been confirmed [3].the main limitations inherent to the ANAMMOX process are requirement of a long start-up period and instability mainly because of slow growth rates and sensitivity of ANAMMOX bacteria [4,5,6,7]. Several kinds of sludge samples, including conventional activated sludge[S-9],nitrifying activated sludge[I0],anaerobic granular sludge[II] and the mixed microbial consortium from different sludge [4, 12], were mainly used as inocula for ANAMMOX process. Three kinds of seeding sludge, i.e. conventional activated sludge, anaerobic granular sludge and the nitrifying activated sludge from the nitritation reactor treating aged leachates were evaluated in batch mode to screen the optimized inoculum for the rapid start-up of ANAMMOX reactor. The applicability of the ANAMMOX process for the treatment of aged leachates was investigated
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