Microbial Flocs Suspended Biofilms

2003 ◽  
Author(s):  
Steven N. Liss
Keyword(s):  
Microbial Flocs

The Effect of Microbial Flocs Size and Structure on UV Disinfection

2011 ◽  
Vol 2011 (3) ◽  
pp. 92-109
Author(s):  
Y. Azimi ◽  
D. G. Allen ◽  
B. Cairns ◽  
R. R. Farnood
Keyword(s):  
Uv Disinfection ◽  
Microbial Flocs ◽  
Size And Structure

scholarly journals Isolation, Separation and Identification of the Extracellular Polymeric Substance (EPS) Protein Fraction from the Activated Sludge Floc

2021 ◽  
Author(s):  
Elena Brei
Keyword(s):  
Mass Spectrum ◽  
Activated Sludge ◽  
Extracellular Polymeric Substances ◽  
Current Knowledge ◽  
Noncovalent Interactions ◽  
Detection Methods ◽  
Structure Stability ◽  
Major Protein ◽  
Substantial Portion ◽  
Microbial Flocs

The purpose of this study was to expand the current knowledge of the composition of extracellular polymeric substances (EPS), principally EPS proteins, and their influence on structure, stability and surface chemistry of microbial flocs in activated sludge. It was proposed that a substantial portion of EPS proteins contains glycoproteins or proteins that are strongly bound noncovalently to carbohydrates. Various buffer additives, purification and precipitation methods were employed for protein purification and several glycoprotein detection methods were utilized for glycoprotein detection in the EPS. The proteins were separated with success, with a substantial portion suggesting either a possible glycosylation or strong noncovalent interactions with carbohydrate moiety. An enzyme, oligoendopeptidase F from M3B family was tentatively identified as a major protein present. These results suggest that proteins in the activated sludge EPS may exist in a very intricate arrangement. Furthermore, the EPS peptides may get degraded by naturally present enzymes in the EPS after the protein is digested prior to mass spectrum (MS), making the identification challenging.

Characteristics of different fractions of microbial flocs and their role in membrane fouling

2011 ◽  
Vol 63 (2) ◽  
pp. 262-269 ◽  
Author(s):  
H. J. Lin ◽  
W. J. Gao ◽  
K. T. Leung ◽  
B. Q. Liao
Keyword(s):  
Microbial Community ◽  
Membrane Fouling ◽  
Extracellular Polymeric Substances ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Sludge Flocs ◽  
Microbial Flocs ◽  
Thermomechanical Pulping ◽  
Gradient Gel Electrophoresis ◽  
Sludge Cake ◽  
The Difference

Characteristics of different fractions (small flocs vs. large flocs) of sludge flocs from a submerged anaerobic membrane bioreactor treating thermomechanical pulping (TMP) whitewater were determined using various analytic techniques, including extraction and chemical analysis of extracellular polymeric substances (EPS), particle size analyzer, and polymer chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). The results showed that the fraction of smaller flocs contained a higher level of bound EPS and had a higher fractal dimension as compared to the fraction of larger flocs. PCR-DGGE analysis indicated that there were significant differences in microbial community between the fraction of smaller flocs and large flocs. The microbial community of the smaller flocs was similar to that of the sludge cake layers, indicating the pioneering role of the microbial community in smaller flocs in membrane fouling. These findings provide a new insight in the difference of membrane fouling potential between smaller flocs and larger flocs fraction.

scholarly journals Characterization of microbial aggregates in relation to membrane biofouling in submerged membrane bioreactors

2021 ◽  
Author(s):  
Heather Elizabeth Kraemer
Keyword(s):  
Laser Scanning ◽  
Extracellular Polymeric Substances ◽  
Municipal Wastewater ◽  
Pilot Scale ◽  
Membrane Bioreactors ◽  
Laser Scanning Microscopy ◽  
The Other ◽  
Major Constituent ◽  
Confocal Laser ◽  
Microbial Flocs

The purpose of this study was to characterize microbial aggregates and extracellular polymeric substances (EPS) that contribute to biofouling of submerged polymeric microfiltration membranes. Two issues were addressed in this study, (1) the influence operational and recovery cleanings of membranes have on biofouling amelioration and (2) the influence physicochemical properties of microbial flocs have on biofouling. The experiments in this study employed two pilot scale Zee Weed™ membrane bioreactors (MBRs). In one MBR, a ZW-I0 module was installed to treat secondary municipal wastewater at a sludge retention time (SRT) of30 days and operated under permeate/relaxation conditions. In the other MBR, two ZW -10 modules were installed to treat secondary municipal wastewater at an SRT of 12 days. One module operated under permeate/relaxation conditions, while the other operated under permeate/backwash conditions. Sludge samples from the MBRs were characterized by measuring the surface charge, hydrophobicity, and EPS composition of the microbial flocs. Membrane fibre samples were collected from each ZW -10 module during permeation and after recovery cleanings. The biofoulant on the membrane was analyzed using confocal laser scanning microscopy (CLSM) after simultaneous staining with the lectins concanavalin A (ConA), wheat germ agglutinin (WGA), and soybean agglutinin (SBA). The CLSM analysis of the membrane fibres sampled showed that the biofoulant on the membrane was composed of a heterogeneous colonization of microbes and EPS known to contain glucose, mannose, N -acetylglucosamine, and galactose. The dominant carbohydrate in the biofoulant was shown to be N -acetylglucosamine, which is part of both the cell wall of bacteria and the extracellular matrix. The reversible biofoulant was composed of individual cells, aggregates of cells, and EPS. The major constituent of the irreversible biofoulant was inferred to be EPS, which was observed as a fibrous network of material that remained adhered to the membrane after recovery cleaning the modules with a 2000 ppm hypochlorite solution. By using a permeate backwash rather than relaxation as an operational cleaning method, the rate of biofouling may be reduced. The rate of biofoulant accumulation on hydrophilic membranes may be reduced at higher SR Ts because the biomass at higher SR Ts has a higher hydrophobicity when compared to the biomass at lower SRTs.

scholarly journals Incorporation of hydrophobized mineral particles in activated sludge flocs: a way to assess ballasting efficiency

2005 ◽  
Vol 52 (10-11) ◽  
pp. 177-184 ◽  
Author(s):  
G. Defontaine ◽  
J. Thormann ◽  
B.S. Lartiges ◽  
A.G. El Samrani ◽  
O. Barrès
Keyword(s):  
Activated Sludge ◽  
Optical Microscopy ◽  
Sodium Oleate ◽  
Surface Hydrophobicity ◽  
Mineral Surface ◽  
Coated Particles ◽  
Sludge Flocs ◽  
Mineral Particles ◽  
Microbial Flocs

The role of mineral surface hydrophobicity in attachment to activated sludge flocs was investigated. Fluorite and quartz particles of similar granulometry were hydrophobized by adsorbing sodium oleate and dodecylamine chloride, respectively. Mineral hydrophobicity was assessed by flotation expriments. The attachment of particles to microbial flocs was determined by optical microscopy. The results indicate that hydrophobized particles are always better incorporated within activated sludge flocs than non-coated particles. A comparison with Aquatal particles used as sludge ballast reveals that hydrophobized minerals are associated with microbial flocs to the same extent.

Microbial floc stabilization and preparation for structural analysis by correlative microscopy

1996 ◽  
Vol 34 (5-6) ◽  
pp. 155-162 ◽  
Author(s):  
Ian G. Droppo ◽  
Derrick T. Flannigan ◽  
Gary G. Leppard ◽  
Steven N. Liss
Keyword(s):  
Three Dimensional ◽  
Microscopic Analysis ◽  
Confocal Laser ◽  
Natural State ◽  
Correlative Microscopy ◽  
Floc Size ◽  
Microbial Flocs ◽  
Multiple Sampling ◽  
Transmission Electron ◽  
The Matrix

In the analysis of microbial flocs from activated sludge it is important to stabilize these structures and their components for structural studies sufficiently to assess, minimize and conceptually balance artifacts, particularly during manipulation. By employing multi-technique stabilization and immediate preservation it is possible to analyze a single sample by correlative microscopy (conventional optical microscopy (COM), scanning confocal laser microscopy (SCLM), and transmission electron microscopy (TEM)). This approach minimizes variability associated with multiple sampling. Floc samples were collected using plankton chambers consisting of reservoirs with a removable circular microscope slide. Flocs which come to rest on the slide are stabilized within low melting point agarose. The solidified gel is a clear, highly porous and resilient medium amenable to further staining, washing, sub-sampling or direct microscopic analysis. Stabilization in agarose was found not to significantly influence floc size distribution. The use of agarose was found to be compatible with SCLM and TEM techniques and minimized perturbations. Agar-embedded samples were easily infused with Nanoplast, a hydrophilic melamine resin, which stabilizes material in its natural state. This facilitates the ultrastructural analysis of the three-dimensional fibrillar architecture of the floc matrix. The matrix is found to consist of complex pores bounded by fibrils of 4-6 nm diameter.

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