Formation and microbial community analysis of chloroanilines-degrading aerobic granules in the sequencing airlift bioreactor.

AIMS

This paper investigates a selection-based acclimation strategy for improving the performance and stability of aerobic granules at a high chloroanilines loading.

METHODS AND RESULTS

The experiments were conducted in a sequencing airlift bioreactor (SABR) to develop aerobic granules fed with chloroanilines (ClA). The evolution of aerobic granulation was monitored using image analysis and scanning electron microscopy, and PCR-DGGE analysis of microbial community was performed. The sludge granulation was apparently developed by decreased settling time and gradual increased ClA loading to 0.8 kg m(-3) day(-1). A steady-state performance of the granular SABR was reached at last, as evidenced by biomass concentration of 6.3 g l(-1) and constant ClA removal efficiency of 99.9%. The mature granules had a mean size of 1.55 mm, minimal settling velocity of 68.4 m h(-1), specific ClA degradation rate of 0.181 g gVSS(-1) day(-1). Phylogenetic analysis of aerobic ClA-degrading granules confirmed the dominance of beta-, gamma-Proteobacteria and Flavobacteria.

CONCLUSIONS

The chosen operating strategy involving step increase in ClA loading and enhancement of major selection pressures was successful in cultivating the aerobic ClA-degrading granules.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research could be helpful for improving the stability of aerobic granules via optimizing operating conditions and developing economic feasible full-scale granular bioreactor.