Abstract: Slow growth of anaerobic ammonium oxidation(ANAMMOX) microbes is one of the main problems with practical application of ANAMMOX process.So it is very important to select a proper type of sludge for inoculation of the ANAMMOX microbes.Three different types of sludge,i.e.aerobic sludge,anaerobic granular sludge and anaerobic digestion sludge,were selected in the experiment and inoculated with ANAMMOX microbes.After 61,70,85 days of incubation in anaerobic squencing batch reactors(ASBR) separately,ammonium removal rate reached 82%,92%,and 91%,respectively and total nitrogen removal rate 76%,82%,and 80%,respectively in the three samples,and pH of the water discharged from Reactor R1,R2 and R3 remained at 8.4,8.5 and 8.5,respectively.The aerobic sludge turned into floccules,better in settleability than its precendent and the anaerobic granular sludge was disintegrated into sludge composed of particles of sizes ranging mainly from 0.5 to 1.0 mm,while the anaerobic digestion sludge became sandy with small particles.Based on the chemometrics of cell yield coefficient of the ANAMMOX bacteria and the NH₄⁺-N and NO₂^- -N removal rate and NO₃^--N generation rate,the yield coefficient of the ANAMMOX bacteria were figured out as 0.080,0.105 and 0.114 mol CH₂O_0.5N_0.15/mol NH₄⁺,respectively,suggesting that the ANAMMOX bacteria in the reactors attenuated to a varying extent.To sum up,anaerobic granular sludge is the best for enrichment of ANAMMOX bacteria.

Key words: ANAMMOX, inoculated sludge, start-up