Bacterial composition of activated sludge - importance for floc and sludge properties

2004 ◽  
Vol 49 (10) ◽  
pp. 51-58 ◽  
Author(s):  
P.H. Nielsen ◽  
T.R. Thomsen ◽  
J.L. Nielsen
Keyword(s):  
Activated Sludge ◽  
Sludge Flocs ◽  
Floc Structure ◽  
Culture Independent ◽  
In Situ Methods ◽  
Sludge Properties ◽  
And Function ◽  
Biological Methods ◽  
Dominant Bacteria

Activated sludge flocs consist of numerous constituents which, together with other factors, are responsible for floc structure and floc properties. These properties largely determine the sludge properties such as flocculation, settling and dewaterability. In this paper we briefly review the present knowledge about the role of bacteria in relation to floc and sludge properties, and we present a new approach to investigate the identity and function of the bacteria in the activated sludge flocs. The approach includes identification of the important bacteria and a characterization of their physiological and functional properties. It is carried out by use of culture-independent molecular biological methods linked with other methods to study the physiology and function, maintaining a single cell resolution. Using this approach it was found that floc-forming properties differed among the various bacterial groups, e.g. that different microcolony-forming bacteria had very different sensitivities to shear and that some of them deflocculated under anaerobic conditions. In our opinion, the approach to combine identity with functional analysis of the dominant bacteria in activated sludge by in situ methods is a very promising way to investigate correlations between presence of specific bacteria, and floc and sludge properties that are of interest.

Effects of potassium ion on sludge settling, dewatering and effluent properties

1998 ◽  
Vol 37 (4-5) ◽  
pp. 317-324 ◽  
Author(s):  
Sudhir N. Murthy ◽  
John T. Novak
Keyword(s):  
Activated Sludge ◽  
Field Studies ◽  
Potassium Ion ◽  
Potassium Ions ◽  
Nutrient Requirements ◽  
Sludge Dewatering ◽  
Capillary Suction ◽  
Sludge Flocs ◽  
Sludge Properties ◽  
Sludge Settling

Potassium ions appear to play an important role in determining the nature of activated sludge flocs. Relative to sodium, the concentration of potassium ions in most industrial activated sludge is typically low. Laboratory and field studies were conducted to examine the influence of potassium on activated sludge properties. The concentration of potassium affected the concentration of readily extractable (slime) proteins in the floc and the proteins in the surrounding solution. In laboratory tests, an increase in this cation's concentration beyond nutrient requirements impeded sludge dewatering properties as measured by capillary suction time (CST) and specific resistance to filtration (SRF) and associated with an increase in soluble protein. An increase in effluent total organic carbon and effluent turbidity was observed at higher concentrations of this ion. Conversely, an increase in concentration of potassium ion improved the settling properties of sludge with low equivalent monovalent to divalent cation ratio.

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.

Microscopic and enzymatic investigations on biofilms of wastewater treatment systems

1997 ◽  
Vol 36 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Tanja Gschlößl ◽  
Ingrid Michel ◽  
Marion Heiter ◽  
Christian Nerger ◽  
Verena Rehbein
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Biological Properties ◽  
Organic Substances ◽  
Operational Conditions ◽  
Sludge Flocs ◽  
And Performance ◽  
The Stability

In biological wastewater treatment inorganic and organic substances are fixed and metabolized by mixed populations of microorganisms forming either activated sludge flocs or biofilms. Not only the type of wastewater but also the operational conditions promote the development of an adapted biocenosis of microorganisms with specialized enzymatic functions. Understanding the biological properties of the microorganisms, it is possible to assess the prevailing conditions in their natural environment. Regular microscopic and enzymatic investigations of activated sludge and biofilms thus improve the assessment of the stability of the processes and support troubleshooting in wastewater treatment plants. While the role of bacteria is often discussed, the importance of ciliated protozoes and metazoes for the maintenance of the stability of biofilm systems is rarely mentioned. In this paper we intend to show some new results of direct microscopic observations in different sorts of biofilm systems focussing upon ciliated protozoes and metazoes. Practical results will demonstrate the relation between enzymatic analysis, microscopic investigations and performance of biofilm systems.

scholarly journals Application of Universal Stress Proteins in Probing the Dynamics of Potent Degraders in Complex Terephthalate Metagenome

2013 ◽  
Vol 2013 ◽  
pp. 1-21
Author(s):  
Andreas N. Mbah ◽  
Raphael D. Isokpehi
Keyword(s):  
Activated Sludge ◽  
Stress Proteins ◽  
Microbial Population ◽  
Bacillus Halodurans ◽  
Environmental Genomics ◽  
Culture Independent ◽  
Methanothermus Fervidus ◽  
Alicyclobacillus Acidocaldarius ◽  
And Function ◽  
The Impact

The culture-independent strategies to study microbial diversity and function have led to a revolution in environmental genomics, enabling fundamental questions about the distribution of microbes and their influence on bioremediation to be addressed. In this research we used the expression of universal stress proteins as a probe to determine the changes in degrading microbial population from a highly toxic terephthalate wastewater to a less toxic activated sludge bioreactor. The impact of relative toxicities was significantly elaborated at the levels of genus and species. The results indicated that 23 similar prokaryotic phyla were represented in both metagenomes irrespective of their relative abundance. Furthermore, the following bacteria taxa Micromonosporaceae,Streptomyces, Cyanothecesp. PCC 7822,Alicyclobacillus acidocaldarius, Bacillus halodurans, Leuconostoc mesenteroides, Lactococcus garvieae, Brucellaceae,Ralstonia solanacearum, Verminephrobacter eiseniae,Azoarcus,Acidithiobacillus ferrooxidans, Francisella tularensis, Methanothermus fervidus,andMethanocorpusculum labreanumwere represented only in the activated sludge bioreactor. These highly dynamic microbes could serve as taxonomic biomarkers for toxic thresholds related to terephthalate and its derivatives. This paper, highlights the application of universal stress proteins in metagenomics analysis. Dynamics of microbial consortium of this nature can have future in biotechnological applications in bioremediation of toxic chemicals and radionuclides.

scholarly journals Unity, Continuity, Structure, and Function. The Ongoing Search for a Deeper Understanding of the Many Roles Attributed to Fascia in the Living Human Body - An Osteopathic Perspective

2020 ◽  
Vol 06 (03) ◽  
pp. 1-1
Author(s):  
Colin Armstrong ◽  
Keyword(s):  
Human Body ◽  
The Body ◽  
Human Form ◽  
In Situ Methods ◽  
Living Organisms ◽  
The Many ◽  
And Function ◽  
Dynamic Interplay

Progress in technologies, notably in vivo and in situ methods, has equipped scientists with the necessary skills to explore the living human body in increasingly minute detail. This has led to a better understanding of the dynamic interplay between the various elements that make up the living human body. To further understand the interplay, this research focuses on the insights and observations of the founders of osteopathy, who placed great importance on the role of fascia in the body. Modern anatomical investigation still relies heavily on dissection to describe the structural organization of living organisms. Therefore, at present, a major challenge faced by modern anatomists is to move towards a more holistic and integrative understanding of the unity, continuity, and dynamic interplay between the various elements that come together to create the living human form.

scholarly journals The Impact of Aluminium Salt Dosing for Chemical Phosphorus Removal on the Settleability of Activated Sludge

Environments ◽  
2018 ◽  
Vol 5 (8) ◽  
pp. 88 ◽  
Author(s):  
Peter Ojo ◽  
Augustine Ifelebuegu
Keyword(s):  
Activated Sludge ◽  
Settling Velocity ◽  
Treated Wastewater ◽  
Volume Index ◽  
Sem Images ◽  
Sludge Flocs ◽  
Floc Structure ◽  
Aluminium Salt ◽  
Dose Concentration ◽  
The Impact

The use of metal salts like aluminium in the precipitation of phosphorus in activated sludge plants has increased considerably in recent years due to the need to achieve tighter discharge consents for phosphorus in treated wastewater effluent. The impact of aluminium salt (Al3+) dosing on the settleability of activated sludge as a function of zone settling velocity (ZSV) and stirred specific volume index (SSVI) were investigated in batch settleability tests over a three-year period. The results showed that ZSV increased with increasing dose of aluminium salt as SSVI decreased. This trend was observed for dosing concentrations of less than 100 mg/L. At a dose concentration >100 mg/L, the trend was reversed as ZSV decreased and SSVI increased. At dose concentrations of <100 mg/L, Al3+ helped in the bioaggregation of dispersed activated sludge flocs, thereby improving settleability. The surface morphology from the scanning electron microscope (SEM) images indicated that the initial potential of interfloc bridging, open floc formation, and spindly bulking noticed in the undosed activated sludge flocs were remarkably reduced as the flocs became more compacted after Al3+ treatment. At >100 mg/L of Al3+, the sludge settleability started to disintegrate due mainly to surface charge reversal linked to the formation of aluminium hydroxides and the resultant disintegration of the activated sludge floc structure.

scholarly journals mTORC2 affects the maintenance of the muscle stem cell pool

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Nathalie Rion ◽  
Perrine Castets ◽  
Shuo Lin ◽  
Leonie Enderle ◽  
Judith R. Reinhard ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Mammalian Target Of Rapamycin ◽  
Adult Skeletal Muscle ◽  
Muscle Stem Cells ◽  
And Function ◽  
Muscle Homeostasis ◽  
Biological Methods

Abstract Background The mammalian target of rapamycin complex 2 (mTORC2), containing the essential protein rictor, regulates cellular metabolism and cytoskeletal organization by phosphorylating protein kinases, such as PKB/Akt, PKC, and SGK. Inactivation of mTORC2 signaling in adult skeletal muscle affects its metabolism, but not muscle morphology and function. However, the role of mTORC2 in adult muscle stem cells (MuSCs) has not been investigated. Method Using histological, biochemical, and molecular biological methods, we characterized the muscle phenotype of mice depleted for rictor in the Myf5-lineage (RImyfKO) and of mice depleted for rictor in skeletal muscle fibers (RImKO). The proliferative and myogenic potential of MuSCs was analyzed upon cardiotoxin-induced injury in vivo and in isolated myofibers in vitro. Results Skeletal muscle of young and 14-month-old RImyfKO mice appeared normal in composition and function. MuSCs from young RImyfKO mice exhibited a similar capacity to proliferate, differentiate, and fuse as controls. In contrast, the number of MuSCs was lower in young RImyfKO mice than in controls after two consecutive rounds of cardiotoxin-induced muscle regeneration. Similarly, the number of MuSCs in RImyfKO mice decreased with age, which correlated with a decline in the regenerative capacity of mutant muscle. Interestingly, reduction in the number of MuSCs was also observed in 14-month-old RImKO muscle. Conclusions Our study shows that mTORC2 signaling is dispensable for myofiber formation, but contributes to the homeostasis of MuSCs. Loss of mTORC2 does not affect their myogenic function, but impairs the replenishment of MuSCs after repeated injuries and their maintenance during aging. These results point to an important role of mTORC2 signaling in MuSC for muscle homeostasis.

Bioflocculation in Activated Sludge, an Analytic Approach

1992 ◽  
Vol 25 (4-5) ◽  
pp. 441-443 ◽  
Author(s):  
V. Urbain ◽  
J. C. Block ◽  
J. Manem
Keyword(s):  
Activated Sludge ◽  
Hydrophobic Interactions ◽  
Surface Characteristics ◽  
Positive Role ◽  
Sludge Flocs ◽  
Physico Chemical ◽  
Micro Organisms ◽  
Different Origins ◽  
Sludge Settleability

A study on the physico-chemical structure of activated sludge flocs was carried out to get a better insight in its relation with sludge settleability. For this purpose, sixteen sludges from different origins were analysed in order to provide information with regard to their settleability, biomass and exocellular composition, surface characteristics and internal hydrophobicity. The presence of filamentous micro-organisms was observed in all samples but was not always associated with poor settleability, supporting to some extent the idea of their role as a backbone in the flocs. The relations between variables were studied through their linear correlations. Exocellular polymers (ECP) were associated with poor settling conditions. The chemical composition of the ECP (the DNA fraction and the C/N ratio) had an influence on the surface characteristics of the flocs. Finally, sludge settleability was described with a mathematical model, opposing the ECP and the internal hydrophobicity of the flocs. The positive role of hydrophobic interactions, in term of settleability, should provide a new approach in the understanding of flocculation mechanisms in activated sludge.

Study on Activated Sludge Properties of A/A/O Combined Membrane Bioreactor during Startup Period

2011 ◽  
Vol 374-377 ◽  
pp. 836-839
Author(s):  
Shuo Liu ◽  
Bao Zhen Wang ◽  
Xu Yang
Keyword(s):  
Activated Sludge ◽  
Membrane Fouling ◽  
Operation Time ◽  
Biological Properties ◽  
Sludge Flocs ◽  
Fouling Control ◽  
Conventional Activated Sludge ◽  
Sludge Properties ◽  
Startup Period ◽  
Sludge Activity

To improve treatment performance and alleviate membrane fouling, the physical and biological properties of sludge in combined MBR which divided into anoxic, anaerobic and aerobic zone were studied. During initial startup period, the sludge in A/A/O combined MBR was suspended growth, after textile carrier package, the sludge was suspended and fixed growth. The biomass analysis showed that with the increase of operation time, MLVSS/MLSS decreased from 0.93 to 0.72 which certified that high MLSS concentration caused biomass growth slow gradually, while packing textile carrier could supply attached biomass which maximum value was 0.18g/cm(3777.8mg/L). Meanwhile, high MLSS concentration also resluted in high sludge viscosity which could reach to 35.42mPa•s and decreased sludge activity. Particle size anaylisis showed that shear stress of aeration made the sludge flocs smaller than conventional activated sludge process. All the sludge properties which had been analysis in this study showed A/A/O combined MBR had great difference from conventional MBR process, and some parameters could be used for membrane fouling control in A/A/O combined MBR for wastewater treatment project.

Chemical description of extracellular polymers: implication on activated sludge floc structure

1998 ◽  
Vol 38 (8-9) ◽  
pp. 45-53 ◽  
Author(s):  
M.-F. Dignac ◽  
V. Urbain ◽  
D. Rybacki ◽  
A. Bruchet ◽  
D. Snidaro ◽  
...  
Keyword(s):  
Amino Acids ◽  
Activated Sludge ◽  
Cation Exchange Resin ◽  
Monosaccharide Composition ◽  
Major Constituent ◽  
Extracellular Polysaccharides ◽  
Extracellular Polymers ◽  
Floc Structure ◽  
Different Origins

Activated sludge extracellular polymers (ECP) were extracted either by sonication or a combination of sonication and cation exchange resin treatment (CER). The chemical composition of the aqueous extract was investigated by chromatographic analysis of amino acids and sugars after hydrolysis. Up to 70 to 80% of the total organic carbon (TOC) of ECP was characterized. Proteins were found to be the major constituent of ECP, which was confirmed by pyrolysis/GC/MS analysis. Sugar and protein analysis led to complementary information both on the origin of extracellular material and on sludge floc structure. The monosaccharide composition in ECP and sludge allowed the proposal of different origins for extracellular polysaccharides. The predominance of proteins in ECP underlined their key role in the floc structure, and led to hypotheses on their origin. Proteins were better extracted than sugars when the CER extraction was combined with sonication. This supposed that proteins are more involved than sugars in electrostatic bonds with multivalent cations. Electrostatic bonds were found to be uniformly distributed in the floc and closely combined with hydrophobic bonds. About 25% of ECP amino acids were negatively charged and 24% exhibited hydrophobic properties, highlighting the specific role of proteins in the floc structure.

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