Physical Characteristics of Activated Sludge Flocs

Li, DaHong; Ganczarczyk, Jerzy J.; Jenkins, David

doi:10.1080/10643388609388329

Cited by 48 publications

(19 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…6. It was distinctly that compared with big flocs, the micro flocs in activated sludge consisting of more dispersed nitrifying microorganisms such as ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) could significantly improve denitrification due to less oxygen limitation, once they were exposed to large bulk of aerated-anoxic environment [14,33]. According to PCR-DGGE and sequencing analysis (in Table 4), furthermore, these small sized flocs were also constituted by substantial biomass including uncultured bacterium Bacteroidetes, a,e,d-proteobacteria, Chloroflexi, and Firmicutes, as well as enrichment culture bacterium, indicating the co-existing of aerobic, microaerophilic and denitrifying bacteria performing SND capacity [16].…”

Section: Identification Of Snd By Micro-environment Characteristicsmentioning

confidence: 99%

Identification and evaluation of SND in a full-scale multi-channel oxidation ditch system under different aeration modes

Zhou

Han

Guo

2015

Chemical Engineering Journal

View full text Add to dashboard Cite

h i g h l i g h t sSND was observed in a multi-channel OD at very low DO of 0.10-0.25 mg L À1 . SND was identified by micro-environment characteristics within tiny flocs. The highest SND occupied 44.1% of influent nitrogen mass by NMB analysis. The maximum SND efficiency was 79% with SND rate of 5.09 mg L À1 h À1 . a r t i c l e i n f o t r a c tSimultaneous nitrification and denitrification (SND) was evidently observed in a full-scale multi-channel oxidation ditch (OD), especially occurring within the outer channel under microaerophilic conditions. The optimum average dissolved oxygen (DO) concentration for SND was 0.25 mg L À1 with 79% SND efficiency and 5.09 mg L À1 h À1 SND rate, leading to 74.9% overall TN removal efficiency. Small sized flocs consisting of more nitrifying bacteria enhanced nitrification in favor of SND due to less oxygen diffusion limitation inside flocs than larger flocs under micro-aerated conditions. SND was also identified by co-existing of nitrifying and denitrifying bacteria as well as some microaerophilic microorganisms based on molecular biology analysis. Nitrogen mass balances (NMB) quantitatively demonstrated that the highest SND efficiency accounted for 44.1% of influent nitrogen mass. Above valuable findings might deeply reveal SND as a principal mechanism of nitrogen removal in a multi-channel OD from macro-to micro-scale.

show abstract

Section: Identification Of Snd By Micro-environment Characteristicsmentioning

confidence: 99%

Identification and evaluation of SND in a full-scale multi-channel oxidation ditch system under different aeration modes

Zhou

Han

Guo

2015

Chemical Engineering Journal

View full text Add to dashboard Cite

show abstract

“…Computer software is required for the image processing and analysis and a variety of commercial products are available. Image analysis is often combined with microscopy by mounting a CCD camera onto the microscope (Li and Ganczarczyk, 1986;Cousin and Ganczarczyk, 1998;da Motta et al, 2001;Kobayashi, 2004). The advent of photography and image analysis has allowed much quicker measurements of an almost inexhaustible number of different floc size measurements to be made from floc samples when compared to traditional microscope methods (Wang and Gregory, 2002).…”

Section: Photography and Image Analysismentioning

confidence: 99%

“…Activated sludge 245-377 Li and Ganczarczyk (1986) Polystyrene beads 500+ Spicer and Pratsinis (1996) Activated sludge 70+ da Motta et al (2001) Alum flocs ∼ 100 Gorczyca and Ganczarczyk (1999) …”

Section: Type Of Floc Under Investigation Number Of Flocs Measured Aumentioning

confidence: 99%

See 1 more Smart Citation

Measuring Floc Structural Characteristics

Jarvis

Jefferson

Parsons

2005

Rev Environ Sci Biotechnol

107

View full text Add to dashboard Cite

“…Separation efficiency is largely affected by the activated sludge structure in terms of the particle size distribution of the flocs. The particle size distribution of activated sludge is bimodal, containing two classes, i.e., aggregated flocs (25-100 lm) and free cells (B5 lm) (Li and Ganczarczyk 1991;Mikkelsen and Kelding 2002). Aggregated flocs consist of a multitude of bacteria and extracellular polymeric substance.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of free cells and aggregated flocs for the flocculation and sedimentation of activated sludge

2015

Int. J. Environ. Sci. Technol.

View full text Add to dashboard Cite

Laboratory experiments were conducted to investigate the correlation of the free cells/aggregated flocs characteristics and the sludge flocculation and separation behavior during the activated sludge process. Activated sludge was cultured in three laboratory-scale batch reactors with same carbon sources of glucose but different sludge retention times (SRTs) of 5, 10 and 20 days. The variation in the operation condition produced sludge with different flocculation and separation characteristics. The reactor performance in terms of bioflocculation as measured by the amount of suspended solids in the effluent, sludge sedimentation and compression as measured by the sludge value index improved considerably as the SRT lengthened. The higher SRT was related to less negatively charged surface of free cells and more hydrophobic of aggregated flocs. The negative zeta potential of aggregated flocs (11-13 mV) was smaller than that of free cells (15-23 mV), and free cells carrying lesser negative surface charges resulted in effluent clarification. Hydrophobicity of aggregated flocs (10-17 %) in each reactor was higher than that of free cells (5-8 %). The increase in hydrophobicity of aggregated flocs had positive effect on settleability. Floc strength measured by breakage/erosion index was closely related to hydrophobicity of aggregated flocs, but no correlation could be established with zeta potential of aggregated flocs. In addition, different bacterial species existed in free cells and aggregated flocs. Microbial similarity between free cells and aggregated flocs increased with shorter SRT and was closely related to effluent clarification.

show abstract

Physical Characteristics of Activated Sludge Flocs

Cited by 48 publications

References 62 publications

Identification and evaluation of SND in a full-scale multi-channel oxidation ditch system under different aeration modes

Identification and evaluation of SND in a full-scale multi-channel oxidation ditch system under different aeration modes

Measuring Floc Structural Characteristics

Characteristics of free cells and aggregated flocs for the flocculation and sedimentation of activated sludge

Contact Info

Product

Resources

About