Compatible Solutes Enhance The Efficiency Of Anammox Nitrogen Removal And Its Kinetics

Ca.‘Brocadia sinica'is a common anammox bacteria found in wastewater treatment plants and plays an important role in nitrogen removal of municipal and industrial wastewater.In view of the problem that Ca.‘Brocadia sinica'is susceptible to environmental factors such as high salinity and low temperature,in this work,enhanced nitrogen removal performance and kinetic characteristics of Ca.‘Brocadia sinica'treating high-salinity wastewater or high-salinty and low-temperature wastewater resulting from compatible solutes addition were studied:Nitrogen removal performance and key enzyme activities of Ca.‘Brocadia sinica'treating high-salinity wastewater with sorbitol addition were investigated.Besides,kinetic characteristics of Ca.‘Brocadia sinica'were analyzed through kinetic models.They showed that the nitrogen removal of Ca.‘Brocadia sinica'first increased and then decreased with sorbitol addition.Optimal ammonia removal rate?ARR?and nitrite removal rate?NRR?were 0.53 and 0.67 kg/?m³·d?achieved at 0.8 mM sorbitol,respectively,which increased by 39.5%and 71.8%compared to without sorbitol addition accordingly.NH₄⁺-N and NO₂^--N in the reactor could be completely removed.Independent of sorbitol concentration,extracellular polymeric substance content of Ca.‘Brocadia sinica'was decreased,and hydrazine dehydrogenase and nitrite reductase activities were enhanced about 1.37–2.36 folds.Moreover,remodified Logistic model was the most appropriate to simulate nitrogen removal process,which had higher R².The mean relative error of experimental values and acquired ones by remodified Logistic was2.9%.Kinetic parameters suggested that the addition of sorbitol could shorten the delay time of Ca.‘Brocadia sinica'and fitted R_maxax could be converted into V_maxax to predict the optimal substrate conversion rates of Ca.‘Brocadia sinica'treating high-salinity wastewater within different sorbitol contents.Nitrogen removal performance of Ca.‘Brocadia sinica'treating high-salinty and low-temperature wastewater resulting from glycine addition was investigated.Besides,remodified Logistic model,modified Boltzmann model and modified Gompertz model were performed to analyze kinetic characteristics of Ca.‘Brocadia sinica'with glycine addition.They showed that low glycine content could enhance nitrogen removal performance of Ca.‘Brocadia sinica'in high-salinty and low-temperature wastewater treatment significantly.When glycine were 0.2,0.4,and 0.6 mM,respectively,NRR increased by 27.7%,47.3%,and 70.4%accordingly.Optimal ARR was 0.32 kg/?m³·d?and optimal NRR was 0.45 kg/?m³·d?achieved at 0.8 mM glycine.However,high glycine content could inhibit the activity of Ca.‘Brocadia sinica'and suppressed nitrogen removal.At 1.4 mM glycine,ARR and NRR declined by 30.1%and 16.7%compared to0.8 mM glycine.Moreover,remodified Logistic model and modified Boltzmann model were appropriate to describe nitrogen removal process with glycine addition compared to the modified Gompertz model.Kinetic parameter?achieved through remodified Logistic model revealed that Ca.‘Brocadia sinica'had a shorter lag phase than that of marine anammox bacteria in high-salinty and low-temperature wastewater treatment.