Effect of different kinds of seed sludge and operation modes on start-up of anaerobic ammonia oxidation reactors

Inoculated with riparian sediments, aerobic sludge and anaerobic sludge respectively, six sequencing batch reactors(SBR) were started-up with two operation modes, aerobic nitrification-anammox and direct anammox. The results show that using the way of aerobic nitrification-anammox, reactors inoculated with riparian sediments and aerobic sludge, respectively, achieve the anaerobic ammonia oxidation reaction after operation for 110 d and 165 d. The reactor inoculated with riparian sediments is started-up more rapidly than that for the aerobic sludge, and its NH4 +-N and NO2--N removal efficiencies reach 94% and 99%, respectively. The NH4 +-N and NO2--N removal efficiencies of aerobic sludge reactor are just 53% and 67% at most. However, the reactor inoculated with anaerobic sludge fails to start-up. Under the condition of direct anammox, three reactors are not able to culture anammox bacteria after operation for 190 d.