Innovative start-up strategies for single-stage deammonification with conventional activated sludge: Results of a pilot-scale demonstration

This study investigated innovative start-up strategies of a pilot-scale sequencing batch reactor (SBR) for single-stage deammonification using activated sludge as the sole inoculum source. In 24 m(3) aerobic oxidizing bacteria cultivation plant, nitrogen loss efficiency was suggested to be an indicator for determining duration of cultivation. In 12 m(3) ANAMMOX (ANaerobic AMMonium OXidation) cultivation plant, combined strategy (sequential fed-batch and continuous modes) was adopted to promote ANAMMOX activity from activated sludge. Both the cultivated sludge were inoculated in 24 m(3) pilot-plant for single-stage SBR with deammonification. The feed distribution strategy was used to cultivate ANAMMOX bacteria selectively resulting in nitrogen removal rate of 0.73 kg/m(3)/d and nitrogen removal efficiency of 86.5 +/- 1.9% within 254 days. Candidatus Brocadia sp. 40 was enriched from undetectable to 22.7% relative abundance. These findings indicated that fast start-up of the deammonification process was possible without ANAMMOX seed sludge in pilot-scale reactor with various variables.