Carbon and nitrogen removal through “Candidatus Brocadia sinica”-dominated simultaneous anammox and denitrification (SAD) process treating saline wastewater

Abstract

“Candidatus Brocadia sinica”-dominated simultaneous anammox and denitrification (SAD) process was used to treat nitrogen-rich saline wastewater. The reactor was operated at 30 ± 0.5 °C with influent pH of 7.5 ± 0.1. ‘Ca. B. sinica’ could adapt to high saline surroundings after 42 cycles’ operation. With 100% seawater, nitrogen removal rate and organic removal rate were 0.71 kg/(m3·d) and 0.27 kg/(m3·d), respectively. Both were closed to those without seawater. Independent of salinity, percentage of nitrogen removal by anammox was higher than that by denitrification during the whole treatment period. ‘Ca. B. sinica’ had good tolerance to salinity. However, maximum removal rate of NH4+-N declined with growing salinity. Modified Boltzmann model was proper to analyze the effect resulting from salinity on the maximum removal rate of NH4+-N. Granular sludge characterized by anammox granule embedded in denitrifying granule might play an important role in salt tolerance of anammox bacteria.