To research the effect of pH on nutrients removal and nitrous oxide emissions from an anaerobic/oxygen-limited SBR performing simultaneous nitrification

denitrification and phosphorus removal (SNDPR)

the SNDPR process was successfully developed in an anaerobic/oxygen-limited (DO concentration of 0.3-0.8 mg/L) lab-scale sequencing batch reactor fed with synthetic wastewater mainly containing acetate

ammonia and phosphorus by inoculating with nitritation sludge. The reactor removed (76.1±5)% and (98.4±1)% of the influent nitrogen and phosphorus

respectively. The effect of initial pH on the performance of SNDPR and nitrous oxide emissions was investigated by batch experiments. The results showed that phosphorus was well removed at pH 9.0 and 6.0

and the removal efficiencies were 87.7% and 84.0%

respectively. The ammonia oxidizing rate increased with the decrease of pH from 9.0 to 6.0

and the maximum ammonia oxidizing rate of 3.7 mg/(L · h · g) and nitrogen removal efficiency of 83.9% were gained at pH 6.0. The emission of nitrous oxide decreased with the increase of pH. Specifically

the nitrous oxide emission at pH 6.0 was 3.5 times of that at pH 9.0. This study revealed that the nitrogen and phosphorus could be better removed at pH 6.0

and meanwhile

it could induce more nitrous oxide emissions.