Influence of operational conditions on the stability of aerobic granules from the perspective of quorum sensing.

Integrated aerobic granules were first cultivated in two sequencing batch reactors (SBRs) (A1 and A2). Then, A1's influent organic loading rate (OLR) was changed from alternating to constant (cycling time was still 6 h), while A2's cycling time varied from 6 to 4 h (influent OLR strategy remained alternating). After 30-day operation since the manipulative alternations, granule breakage happened in two reactors at different operational stages, along with the decrease of granule intensity.

Effect of operational strategies on activated sludge's acclimation to phenol, subsequent aerobic granulation, and accumulation of polyhydoxyalkanoates.

Aerobic granules, a relative novel form of microbial aggregate, are capable of degrading many toxic organic pollutants. Appropriate strategy is needed to acclimate seed sludge to the toxic compounds for successful granulation. In this study, two distinct strategies, i.

Understanding of aerobic granulation enhanced by starvation in the perspective of quorum sensing.

Three sequencing batch reactors (M1, M2, and M3) were set up to investigate the influence of different lengths of starvation time (3, 5, and 7 h) on aerobic granulation in the perspective of quorum sensing (QS). Autoinducer-2 (AI-2) level was quantified to evaluate the QS ability of aerobic granules. The results indicated that AI-2 level increased steadily during a cycle of sequencing batch reactors, suggesting that starvation was closely related to AI-2 secretion.

The role of autoinducer-2 in aerobic granulation using alternating feed loadings strategy.

Quorum sensing (QS) plays an important role in aerobic granulation while how QS system regulates the formation of aerobic granules needs further discussion. This study cultivated activated sludge in two identical sequencing batch reactors (R1 and R2) at different influent organic loading rate (OLR) strategies: R1 was operated using constant OLR (around 8.0kg/m(3)d), while R2 was operated at alternating OLR (4.

Accelerated aerobic granulation using alternating feed loadings: alginate-like exopolysaccharides.

Alginate-like exopolysaccharides (ALE) likely contribute markedly to strength of aerobic granules. This study cultivated aerobic granules from propionate wastewaters using strategies with different organic loading rates (OLRs) (4.4-17.

Influence of hydraulic retention time on partial nitrification of continuous-flow aerobic granular-sludge reactor.

This study investigated the effects of hydraulic retention time (HRT) at 12 h, 7.2 h and 2.4 h on partial nitrification efficiency of continuous-flow aerobic granular reactors (CFAGRs) with mature aerobic granules (500 +/- 20mg l-1).

Partial nitrification of wastewaters with high NaCl concentrations by aerobic granules in continuous-flow reactor.

Wastewaters with high salinity are yielded that need sufficient treatment. This study applied aerobic granules to conduct partial nitrification reactions for wastewaters with high NaCl concentrations in a continuous-flow reactor. The present granules revealed partial nitrification performances at nitrite accumulation rate >95% and chemical oxygen demand (COD) removal at >85% at salt concentration up to 50 g l(-1).

Disintegration of aerobic granules: role of second messenger cyclic di-GMP.

Loss of structural stability of aerobic granular process is the challenge for its field applications to treat wastewaters. The second messenger, cyclic diguanylate (c-di-GMP), is widely used by bacteria to regulate the synthesis of exopolysaccharide. This study for the first time confirmed the correlation between concentration of intracellular c-di-GMP and the granular stability under sequencing batch reactor (MBR) mode.

Partial nitrification using aerobic granules in continuous-flow reactor: rapid startup.

This study applied a novel strategy to rapid startup of partial nitrification in continuous-flow reactor using aerobic granules. Mature aerobic granules were first cultivated in a sequencing batch reactor at high chemical oxygen demand in 16 days. The strains including the Pseudoxanthomonas mexicana strain were enriched in cultivated granules to enhance their structural stability.