Effect of EDTA on activated sludge properties

Bacterial extracellular polymers have been found to be important in bioflocculation of activated sludge. In this study ethylene diamine tetra acetic acid (EDTA) method of extracting bacterial extracellular polymers is examined. Following extractions, it is observed that EDTA extracted significant amounts of biopolymers. However, the chemical treatment causes serious changes in sludge properties. Sludge particle size is reduced from 21 mum to 14.6 mum, filtration properties of sludge deteriorates, indicated by an increase of capillary suction time (CST) from 48.1 sec to 232 sec and the viscosity of sludge increases from 5.5 cP to 7.1 cP. The effects are so dramatic, that it is concluded that beyond extracting biopolymers, this technique damages the microbial cell walls and solubilizes some cells.


Effect of carbon to nitrogen ratio on the physical and chemical properties of activated sludge
Durmaz, B; Sanin, Faika Dilek (2003-11-01)
The effect of carbon to nitrogen ratio (C/N) of the feed on the physical and surface chemical properties of activated sludge is investigated. Semi-continuous reactors with 2 liters volume were operated at a mean cell residence time of 8 days. These mixed culture reactors were operated at 3 different carbon to nitrogen ratio. The operation of conventional activated sludge plants treating municipal wastewater is represented with reactors having a C/N ratio of 21 (in terms of the ratio of COD to TKN). Carbon a...
Sanin, Faika Dilek (1994-01-01)
Activated sludge is a flocculated suspension of living and dead microorganisms enmeshed together in a polymer matrix along with some organic and inorganic materials. Extracellular polymers, main components of which are the polysaccharides, proteins, and nucleic acids, act as a protective barrier to the living microbial community, and give the flee its integrity and rigidity. These polymers have been found to affect the dewatering and settling characteristics of activated sludge. Even though they were studie...
Effect of carbon to nitrogen ratio on the composition of microbial extracellular polymers in activated sludge
Durmaz, B; Sanin, Faika Dilek (2001-01-01)
Effect of carbon to nitrogen ratio (C/N) on the sludge extracellular polymer composition is studied in synthetically fed semi-continuous reactors with 8 days of sludge age. Results show that C/N ratio influences the relative distribution of polymer carbohydrate and protein. At low C/N ratio of 5, polymer extracts have high protein and low carbohydrate content. As the C/N ratio is increased to 17.5 and then to 40, carbohydrate concentration increases sharply and protein concentration decreases.
Effect of extracellular polymer composition of activated sludge on the removal of heavy metals by biosorption
Yüncü, Bilgen; Yetiş, Ülkü; Sanin, F. Dilek; Department of Environmental Engineering (2003)
Activated sludge microorganisms can remove many hazardous substances from wastewater by adsorbing and concentrating them on their surfaces. Biosorption of these substances onto activated sludge surfaces are influenced by the chemical properties of the substance in question as well as the surface properties of the microorganisms. The purpose of this study is to identify the biosorption mechanisms of heavy metals and the effect of extracellular polymer (ECP) composition of activated sludge on the biosorption ...
Effect of suppressive DNA on CpG-induced immune activation.
Yamada, H; Gursel, I; Takeshita, F; Conover, J; Ishii, KJ; Gürsel, Mayda; Takeshita, S; Klinman, DM (The American Association of Immunologists, 2002-11-15)
Bacterial DNA and synthetic oligodeoxynucleotides (ODN) containing unmethylated CpG motifs stimulate a strong innate immune response. This stimulation can be abrogated by either removing the CpG DNA or adding inhibitory/suppressive motifs. Suppression is dominant over stimulation and is specific for CpG-induced immune responses (having no effect on LPS- or Con A-induced activation). Individual cells noncompetitively internalize both stimulatory and suppressive ODN. Studies using ODN composed of both stimula...
Citation Formats
F. D. Sanin, “Effect of EDTA on activated sludge properties,” FRESENIUS ENVIRONMENTAL BULLETIN, pp. 165–169, 2001, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/52678.