Responses of Nitrifiers' characteristics to Filling Ratio in IFAS Systems

摘要

The concentrations of (NH_4)~+-N, (NO_2)~--N and (NO_3)~--N were measured in batch experiments to study nitrification kinetics in IFAS system with different FR at 0%-50%. The results showed that both of (NH_4)~+-N oxidation rate (R_((NH_4)~+-n)) and (NO_3)~--N production rate (R_((NO_3)~--N)) increased with FR, which respectively increased from 6.3 to 16.9 mg(NH_4)~+-N·L~(-1) h~(-1) and 0.8 to 13.6 mg(NO_3)~--N·L~(-1)·h~(-1). While the highest accumulation concentration of (NO_2)~--N fell from 51.8 to 9.0 mg·L~(-1). That was, higher FR instead went against to partial nitrification. Quantitative polymerase chain reaction (q-PCR) analysis revealed that increased FR caused an acceleration of the nitrifiers, which correlated linearly with the nitrification rate. Furthermore, the amount of nitrifiers per unit area in biofilm reached maximum at FR = 30%, and it was also the demarcation point when nitrifiers in biofilm outnumbered that in suspended sludge. Cumulative effect of nitrite occurred in the end of reaction when FR was less than 30%.