Assessment of Inocula and N-Removal Performance of Anaerobic Ammonium Oxidation (ANAMMOX) for the Treatment of Aged Landfill Leachates

Abstract

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 feasibility of the ANAMMOX process for the treatment of aged leachates was also investigated in a modified upflow anaerobic sludge blanket (UASB, 0.05m3). The batch experiments revealed that the nitrifying activated sludge from the nitritation reactor could respectively achieve the NRR (nitrogen removal rate) of 0.0365 kg N/(m3.d) and the ARR (ammonium removal rate) of 0.013 kg N/(m3.d) on day 12, which were greatly higher than those of the other two tested sludge samples. The mixture of the aforementioned nitrifying activated sludge and anaerobic granular sludge was established as an effective inoculum for the prompt start-up of ANAMMOX reactor. The maximum total nitrogen removal rate of 0.826 kg N/(m3.d) could be obtained for the treatment of “old” leachates under NLR (nitrogen loading rate) of 1.028 kg N/(m3.d). It is concluded that the N-removal performance of ANAMMOX process is still to be improved for actual engineering application to aged landfill leachates.