Activated sludge foaming: what causes hydrophobicity and can it be manipulated to control foaming?

1998 ◽  
Vol 37 (4-5) ◽  
pp. 503-509 ◽  
Author(s):  
Helen Stratton ◽  
Bob Seviour ◽  
Peter Brooks
Keyword(s):  
Activated Sludge ◽  
Control Strategies ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Mycolic Acid ◽  
Current Control ◽  
Operating Costs ◽  
Foam Formation ◽  
Rhodococcus Rhodochrous ◽  
Stable Foam

Activated sludge aeration tanks frequently suffer from the formation of a stable foam on their surfaces, a problem which results in increased operating costs and reduces performance. Current control strategies are often unsuccessful, mainly because of a lack of understanding of the microbes involved, and often employ expensive and environmentally undesirable procedures, such as the addition of chemicals. Here we have attempted to better understand the mechanism(s) involved in foam formation. We have investigated the possible relationship between the mycolic acid content in a Rhodococcus rhodochrous strain isolated from foam, its cell surface hydrophobicity (CSH) and ability to form stable foam. Results show that mycolic acid composition is not the only contributor to CSH, nor is the CSH the only factor responsible for foam formation and stabilisation. Other possible explanations for mechanisms of foaming and ways to control it are addressed.

In situ detection of cell surface hydrophobicity of probe-defined bacteria in activated sludge

2001 ◽  
Vol 43 (6) ◽  
pp. 97-103 ◽  
Author(s):  
J. L. Nielsen ◽  
L. H. Mikkelsen ◽  
P. H. Nielsen
Keyword(s):  
Activated Sludge ◽  
Surface Properties ◽  
Treatment Plant ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Substrate Uptake ◽  
Filamentous Bacteria ◽  
In Situ Conditions ◽  
Bacterial Surfaces

The surface hydrophobicity of different types of bacteria in activated sludge were investigated under in situ conditions by following the adhesion of fluorescent microspheres with defined surface properties to bacterial surfaces (the MAC-method). This technique was combined with identification of the bacteria with fluorescence in situ hybridization with rRNA-targeted oligonucleotides (FISH) and could thus be used for characterization of surface properties of probe-defined bacteria directly in a complex system without prior enrichment or isolation. This MAC-FISH technique could be used for single bacteria as well as filamentous bacteria. In the investigated activated sludge from an industrial wastewater treatment plant, two types of filamentous bacteria dominated. One morphotype consistently attracted only very few hydrophobic microspheres, indicating that the thin sheath of exopolymers around the cells had a hydrophilic surface. Use of a hierarchical set of gene probes revealed that these filaments were sulphide oxidising Thiothrix spp. The other predominating filamentous morphotype had a thick, very hydrophobic exopolymeric sheath. This filamentous bacterium was found to belong to the alpha-Proteobacteria. The relevance of the significant differences in surface hydrophobicity for the two morphotypes in respect to substrate uptake and floc formation is discussed.

Cell-surface hydrophobicity and scum formation of Rhodococcus rhodochrous strains with different colonial morphologies

1997 ◽  
Vol 82 (2) ◽  
pp. 204-210 ◽  
Author(s):  
M. Sunairi ◽  
N. Iwabuchi ◽  
Y. Yoshizawa ◽  
H. Murooka ◽  
H. Morisaki ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Rhodococcus Rhodochrous

An examination of the mechanisms for stable foam formation in activated sludge systems

2011 ◽  
Vol 45 (5) ◽  
pp. 2146-2154 ◽  
Author(s):  
Steve Petrovski ◽  
Zoe A. Dyson ◽  
Eben S. Quill ◽  
Simon J. McIlroy ◽  
Daniel Tillett ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Foam Formation ◽  
Stable Foam ◽  
Activated Sludge Systems

Physicochemical Aspects of Activated Sludge in Relation to Stable Foam Formation

1992 ◽  
Vol 6 (3) ◽  
pp. 342-350 ◽  
Author(s):  
E. KOCIANOVA ◽  
R. J. FOOT ◽  
C. F. FORSTER
Keyword(s):  
Activated Sludge ◽  
Foam Formation ◽  
Stable Foam

scholarly journals Causes and remedies for filamentous foaming in activated sludge treatment plant

2014 ◽  
Vol 16 (4) ◽  
pp. 762-772 ◽  
Keyword(s):  
Activated Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Mycolic Acid ◽  
Foam Formation ◽  
Activated Sludge Process ◽  
Polymer Addition ◽  
Physical Chemical ◽  
Biological Methods

<p>This paper reviews the problem of foaming associated with the activated sludge process and its control using various physical, chemical and biological methods. Activated sludge process is widely used for treatment of every type of wastewater like industrial, domestic and municipal wastewater. This process is driven by a complex microbial population, among which some mycolic acid containing bacteria leads to the stable foam formation which ultimately results in poor efficiency of the plants and leading to major environmental, operational, and health problems. A number of researches provide the evidences of foaming in wastewater treatment plants and its control using physical, chemical and biological methods. Current approaches for controlling foam includes operational adjustments, additional structures, controlling dissolved oxygen levels, water sprays, steam application, polymer addition, chlorination and a novel and ecofriendly approach that is treatment of filamentous bacteria with the specific phages. A detailed study of all methods is presented and collectively described in this review paper for a better understanding of the foam controlling strategies.&nbsp;</p>

Cell surface and exopolymer characterization of laboratory stabilized activated sludge from a beverage bottling plant

2001 ◽  
Vol 43 (6) ◽  
pp. 175-184 ◽  
Author(s):  
S. M. Boyette ◽  
J. M. Lovett ◽  
W. G. Gaboda ◽  
J. A. Soares
Keyword(s):  
Cell Surface ◽  
Activated Sludge ◽  
Surface Charge ◽  
Electrophoretic Mobility ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Food Sources ◽  
Colloid Titration ◽  
High Concentrations

Fermentor-stabilized activated sludge from an industrial beverage bottling plant was grown on three different food sources: normal plant wastewater, plant wastewater containing high sucrose concentrations, and a synthetic glucose-based feed stock. Surface charge, hydrophobicity, and exopolysaccharide composition were measured on the stabilized bacterial flocs. Cell surface charge was measured by electrophoretic mobility, dye exchange titration, and a standard colloid titration, while cell hydrophobicity was determined using the bacterial adhesion to hydrocarbons (BATH) test. Exopolysaccharide profiles were determined by measuring concentrations of glucose, galactose, mannose, glucuronic, and galacturonic acids in digested exopolymer extractions using HPLC. Changes in the physical surface properties of the bacteria and the chemical composition of the extracted exopolymers were correlated with differences in the three food sources. Cell surface hydrophobicity was similar for cultures grown on different plant wastewaters, while the culture grown on synthetic food produced less floc hydrophobicity. Electrophoretic mobility measurements, charge titrations, and dye exchange titrations showed different total surface charge as well as varying charge availability. Additionally, total surface charge and total exopolysaccharide concentrations appeared less dependent on food source than the food-to-mass ratio. High concentrations of biodegradable food produced dispersed growth and high concentrations of exopolysaccharides that contributed to poor settling.

scholarly journals Quantitative Use of Fluorescent In Situ Hybridization To Examine Relationships between Mycolic Acid-Containing Actinomycetes and Foaming in Activated Sludge Plants

2000 ◽  
Vol 66 (3) ◽  
pp. 1158-1166 ◽  
Author(s):  
Russell J. Davenport ◽  
Thomas P. Curtis ◽  
Michael Goodfellow ◽  
Fiona M. Stainsby ◽  
Marc Bingley
Keyword(s):  
In Situ Hybridization ◽  
Activated Sludge ◽  
Fluorescent In Situ Hybridization ◽  
Threshold Value ◽  
Mycolic Acid ◽  
Foam Formation ◽  
Quantification Method ◽  
Nested Analysis ◽  
The Relationship

ABSTRACT The formation of viscous foams on aeration basins and secondary clarifiers of activated sludge plants is a common and widespread problem. Foam formation is often attributed to the presence of mycolic acid-containing actinomycetes (mycolata). In order to examine the relationship between the number of mycolata and foam, we developed a group-specific probe targeting the 16S rRNA of the mycolata, a protocol to permeabilize mycolata, and a statistically robust quantification method. Statistical analyses showed that a lipase-based permeabilization method was quantitatively superior to previously described methods (P << 0.05). When mixed liquor and foam samples were examined, most of the mycolata present were rods or cocci, although filamentous mycolata were also observed. A nested analysis of variance showed that virtually all of the measured variance occurred between fields of view and not between samples. On this basis we determined that as few as five fields of view could be used to give a statistically meaningful sample. Quantitative fluorescent in situ hybridization (FISH) was used to examine the relationship between foaming and the concentration of mycolata in a 20-m3completely mixed activated sludge plant. Foaming occurred when the number of mycolata exceeded a certain threshold value. Baffling of the plant affected foaming without affecting the number of mycolata. We tentatively estimated that the threshold foaming concentration of mycolata was about 2 × 106 cells ml−1 or 4 × 1012 cells m−2. We concluded that quantitative use of FISH is feasible and that quantification is a prerequisite for rational investigation of foaming in activated sludge.

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