Advances in aerobic granule formation and granule stability in the course of storage and reactor operation

Lee, Dong Hoon; Chen, Yu-You; Show, Kuan‐Yeow; Whiteley, Chris G.; Tay, Joo‐Hwa

doi:10.1016/j.biotechadv.2010.08.007

Cited by 276 publications

(87 citation statements)

References 147 publications

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“…First, irregular granules (138 ± 6 and 49 ± 8 lm of length and width, respectively) were observed after 2 weeks of operation in the first run. No single mechanism is responsible for formation of aerobic granules-this process is strongly influenced by different parameters and factors, like substrate composition, organic loading rate, feeding strategy (feast and famine periods), reactor design, hydrodynamics, settling time, exchange ratio and aeration intensity (Lee et al 2010). However, a critical parameter seems to be short settling time required to retain particles with good settleability.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, it can be successfully used not only for nitrogen and phosphorus removal Wei et al 2014), but also for industrial wastewater treatment (Bumbac et al 2015) and toxic organic compound degradation (Zhu et al 2014). Community structure in aerobic granules is one of the most interesting topics for researchers (de Kreuk and van Loosdrecht 2004;de Kreuk et al 2007;Lee et al 2010;Weissbrodt et al 2013).…”

Section: Introductionmentioning

confidence: 99%

“…Very little knowledge is available on the PAO-GAO competition in AGS (de Kreuk and van Loosdrecht 2004;Lemaire et al 2008;Ahn et al 2009;Winkler et al 2011;Weissbrodt et al 2013). Lots of surveys focused on factors that influence granule formation and stability (Lee et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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The effects of carbon/phosphorus ratio on polyphosphate- and glycogen-accumulating organisms in aerobic granular sludge

Muszyński

Miłobędzka

2015

Int. J. Environ. Sci. Technol.

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A laboratory-scale granular sequencing batch reactor, fed with acetate, was operated at two different ratios of chemical oxygen demand to phosphorus-15:1 and 100:1. Smaller aerobic granules, but with better settleability, were obtained at the lower ratio. High ratio of phosphorus release to uptake of dissolved organic carbon (0.42 mol/mol) coincided with high percentage of polyphosphate-accumulating organisms (up to 70 % of all bacteria) and implied high metabolic activity of these bacteria. Polyphosphate-accumulating organisms belonged mainly to Accumulibacter and Tetrasphaera (46 and 23 %, respectively). Despite significant abundance, Tetrasphaera-related microorganisms were not detected by oligoprobes Actino-221 and Actino-658, but by broader oligoprobes Tet2-892 and Tet3-654. Low abundance (1 %) of Halomonas phosphatis indicated a minor role of these bacteria in the laboratory-scale reactor fed with synthetic wastewater. When the ratio of chemical oxygen demand to phosphorus was increased to 100:1, deterioration of settling properties was observed, caused by growth of filamentous organisms from Thiothrix/021N group. The higher ratio favoured Competibacter and was selected against all groups of polyphosphate-accumulating organisms. However, a significant percentage (10 %) of polyphosphate-accumulating organisms in the granular sludge with concomitant low ratio of phosphorus release to the uptake of dissolved organic carbon (0.01 mol/mol) suggested shift in the overall population metabolism. Under phosphorus limitation in wastewater, polyphosphate-accumulating organisms no longer synthesized poly-P and behaved as glycogen-accumulating organisms.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The effects of carbon/phosphorus ratio on polyphosphate- and glycogen-accumulating organisms in aerobic granular sludge

Muszyński

Miłobędzka

2015

Int. J. Environ. Sci. Technol.

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“…Another positive effect of bacteria on microalgae is enhanced harvesting efficiency (de Bashan et al 2002). Bacteria are the most efficient self-aggregation microorganisms and can form bioaggregates with other microorganisms, resulting in the production of activated sludge, biofilms, aerobic granules, and anaerobic granules (Lee et al 2010;More et al 2014). Bioaggregates usually have good settling capability and are easily separated from treated wastewater.…”

Section: Introductionmentioning

confidence: 99%

Granulation, control of bacterial contamination, and enhanced lipid accumulation by driving nutrient starvation in coupled wastewater treatment and Chlorella regularis cultivation

Zhou

Yang

et al. 2014

Appl Microbiol Biotechnol

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Bacterial contamination and biomass harvesting are still challenges associated with coupling of microalgae and wastewater treatment technology. This study investigated aggregation, bacterial growth, lipid production, and pollutant removal during bacteria contaminated Chlorella regularis cultivation under nutrient starvation stress, by supposing the C/N/P ratios of the medium to 14/1.4/1 (MB₂.₅) and 44/1.4/1 (MB₄.₀), respectively. Granules of 500-650 μm were formed in the bacteria contaminated inoculum; however, purified C. regularis were generally suspended freely in the medium, indicating that bacterial presence was a prerequisite for granulation. Extracellular polymeric substance (EPS) analysis showed that polysaccharides were dominant in granules, while protein mainly distributed in the outer layer. Denaturing gradient gel electrophoresis (DGGE) results revealed Sphingobacteriales bacterium and Sphingobacterium sp. are vital organisms involved in the flocculation of microalgae, and nitrifiers (Stenotrophomonas maltophilia) could co-exist in the granular. Both EPS and DGGE results further supported that bacteria played key roles in granulation. C. regularis was always dominant and determined the total biomass concentration during co-cultivation, but bacterial growth was limited owing to nutrient deficiency. Starvation strategy also contributed to enhancement of lipid accumulation, as lipid content in MB₄.₀ with a greater C/N/P led to the greatest increase in the starvation period, and the maximum lipid productivity reached 0.057 g/(L·day). Chemical oxygen demand and nitrogen removal in MB₄.₀ reached 92 and 96%, respectively, after 3 days of cultivation. Thus, cultivation of microalgae in high C/N/P wastewater enabled simultaneous realization of biomass granulation, bacterial overgrowth limitation, enhanced lipid accumulation, and wastewater purification.

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“…Aerobic granules are densely packed structures of microbial communities that settle significantly faster than activated sludge flocs (de Kreuk and van Loosdrecht 2004; Lee et al 2010;Morgenroth et al 1997) and can contain a wide variety of microbial groups important to wastewater treatment, including acidifying, nitrifying, denitrifying bacteria and other aerobic heterotrophs (Tijhuis et al 1994). Aerobic granules have been used for nitrogen (N) removal in both sequencing batch airlift reactors (SBARs) (Beun et al 2001) and sequencing batch reactors (SBRs) (Jang et al 2003), and can perform simultaneous nitrification, denitrification and phosphorus removal (Yilmaz et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Structural integrity affects nitrogen removal activity of granules in semi-continuous reactors

et al. 2014

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Granules were observed after more than two years of operation in two semi-continuously fed intermittently aerated reactors treating swine wastewater with aerobic:anoxic cycles of 1:1 h and 1:4 h. Subsequently, the granules and flocs were compared with respect to physical characteristics, activity, and microbial community structure. Granules exhibited higher specific nitrification and denitrification rates than flocs. However, once granule structural integrity was disrupted, the rates decreased to levels similar to those of flocs. Membrane hybridizations using 16S rRNA-targeted probes showed that ammonia oxidizing bacteria populations in flocs and granules were dominated by Nitrosomonas and Nitrosococcus mobilis. Granules provided better conditions for Nitrospira compared to flocs. The diversities of the dominant bacterial populations in granules and flocs were not significantly different. Our findings highlight the importance of structural integrity of granules to their nitrogen removing activity.

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Advances in aerobic granule formation and granule stability in the course of storage and reactor operation

Cited by 276 publications

References 147 publications

The effects of carbon/phosphorus ratio on polyphosphate- and glycogen-accumulating organisms in aerobic granular sludge

The effects of carbon/phosphorus ratio on polyphosphate- and glycogen-accumulating organisms in aerobic granular sludge

Granulation, control of bacterial contamination, and enhanced lipid accumulation by driving nutrient starvation in coupled wastewater treatment and Chlorella regularis cultivation

Structural integrity affects nitrogen removal activity of granules in semi-continuous reactors

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