Optimization of nitrogen and carbon removal with simultaneous partial nitrification, anammox and denitrification in membrane bioreactor

Abstract

In this study, a membrane bioreactor (MBR) was used to achieve both nitrogen and carbon removal by a simultaneous partial nitrification, anammox and denitrification (SNAD) process. During the entire experiment, the intermittent aeration (non-aerobic time : aeration time, min min −1 ) cycle was controlled by a time-controlled switch, and the aeration rate was controlled by a gas flowmeter, and the optimal operating parameters as determined by response surface methodology (RSM) were a C/N value of 1.16, a DO value of 0.84 mg l −1 and an aerobic time ( T ae ) of 15.75 min. Under these conditions, the SNAD process achieved efficient and stable nitrogen and carbon removal; the total inorganic nitrogen removal efficiency and chemical oxygen demand removal efficiency were 92.31% and 95.67%, respectively. With the formation of granular sludge, the membrane fouling rate decreased significantly from 35.0 Pa h −1 at SNAD start-up to 19.9 Pa h −1 during stable operation. Fluorescence in situ hybrid analyses confirmed the structural characteristics and the relative ratio of aerobic ammonia-oxidizing bacteria, anaerobic ammonia-oxidizing bacteria and denitrifying bacteria in the SNAD system.

Thickness of hydrogel for nitrifying biomass entrapment determines the free ammonia susceptibility differently in batch and continuous modes

“…The nitrifying bacteria were enriched in PVA hydrogels of different thicknesses, and the speci c oxygen uptake rate (SOUR) values were analyzed using TAN concentration and pH, both which determine FA concentration, as factors in RSA. The statistical mathematical approach of RSA can effectively analyze the complex variations of FA with TAN concentration and pH, and the consequent uctuations in nitrifying performance by deriving a simulation model 30,31 . Based on the results of the RSA, simulations were conducted for TAN concentration and pH to revalidate FA inhibition.…”