The application of glycine betaine to alleviate the inhibitory effect of salinity on one-stage partial nitritation/anammox process.

One-stage partial nitritation/anammox (PN/A) has been proposed as a sustainable method for removing nitrogen from various wastewater. However, the activities of ammonium-oxidizing bacteria (AOB) and anammox bacteria are often inhibited by the exposure to salinity, thereby hindering their wide application in treating industrial wastewater with high salinity. This study reports that the addition of glycine betaine (GB), which is a compatible solute, could alleviate the inhibitory effects of salinity on both AOB and anammox, thereby improving nitrogen removal performance in a one-stage PN/A system. Short-term tests showed that with an addition of GB higher than 1 mM, the activity of AOB and anammox under salinity of 30 g/L could be increased by at least 45% and 51%, respectively. The half-inhibitory concentration of AOB and anammox rose with increasing GB concentration, with 1 mM GB being the optimal cost-effective dosage. Long-term experiments also demonstrated that 1 mM GB addition could enhance nitrogen removal performance and shorten recovery time by 42.9% under a salinity stress of 30 g/L. Collectively, GB addition was found to be a feasible and effective strategy to the counteract adverse effects of salinity on PN/A process. PRACTITIONER POINTS: Glycine betaine (GB) could improving performance of the PN/A process by alleviating the inhibitory effects of salinity on both AOB and anammox bacteria. A GB concentration of 1 mM was found to be optimum in terms of effectiveness and cost. GB addition was a feasible and effective strategy to remain stabilized in the community structure of PN/A sludge. GB could optimize the nitrogen removal performance and shorten the recovery time of PN/A process under saline stress.