and it was lowered when the SRT decreased. SRT was a major factor
influencing the survival of slow-growing nitrifying bacteria in the
system. When SRT was decreased to 15 and 5 d, the nitrifying
bacteria species were found decreasing and become lowest at SRT
of 5 d. The diversity of microorganisms in sludge also influenced the
treatment performance. The MBR operated with high diversity of
bacterial population in sludge provided better treatment performance
and removal efficiencies of phenolic and PAEs compounds.
The microbial population exists under high diversity condition
included heterotrophic bacteria, heterotrophic nitrifying bacteria
and nitrifying bacteria.
3.3. Kinetics of micro-pollutant biodegradation
The batch experiments were set for investigation of phenolic
and PAEs biodegradation by microbial sludge with AOB and
without AOB community via first order biodegradation rate constant
(k). Table 3 shows the k values of target compounds biodegraded
by microbial sludge obtained from different MBR
operating conditions. Meanwhile, the kinetic plots of ammonia
consumption are shown in Fig. 2 and they are used to differentiate
between nitrogen consumption for heterotrophic activity (by heterotrophic
nitrifying bacteria) and autotrophic nitrification by AOB.
When DSMO was used to inhibit nitrifying activity of AOB,