Application of xylitol on nitrogen removal from saline wastewater through "Candidatus Brocadia sinica"-dominated anammox process under low temperature.

Xylitol was first applied to enhance nitrogen removal from saline wastewater through "Candidatus Brocadia sinica"-dominated anammox process under low temperature. The reactor was maintained at 15°C, and the salinity of wastewater was 35 g/L. Ammonium removal rate (ARR) and nitrite removal rate (NRR) were stable at around 0.27 kg/(m  d) without xylitol addition. As an osmotic pressure regulator and cryoprotective agent, optimal ARR and NRR were 0.51 kg/(m  d) and 0.63 kg/(m  d) at 0.3 mM xylitol. At the addition of 1 mM high-dosage xylitol, there existed dissimilatory reduction in nitrate to ammonium nitrogen and heterotrophic denitrification in the reactor. Remodified logistic model was suitable to simulate removal process with xylitol addition. As a result, xylitol dose should be controlled within 0.3 mM, which greatly promoted the nitrogen removal from saline wastewater under low temperature. PRACTITIONER POINTS: Xylitol could be used as osmotic pressure regulator and cryoprotective agent to enhance nitrogen removal. The optimal dose was achieved at 0.3 mM xylitol for "Candidatus Brocadia sinica" in low-temperature saline wastewater. High-dosage xylitol could interfere with nitrogen removal efficiency due to the presence of DNAR and HB. Remodified logistic model was suitable for the analysis and prediction of nitrogen removal process with xylitol addition.