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Enhanced Biological Phosphorus Removal - Carbon Sources, Nitrate as Electron Acceptor, and Characterisation of the Sludge Community

Christensson, Magnus LU (1997)
Abstract
Enhanced biological phosphorus removal (EBPR) was studied in laboratory scale experiments as well as in a full scale EBPR process. The studies were focused on carbon source transformations, the use of nitrate as an electron acceptor and characterisation of the microflora. A continuous anaerobic/aerobic laboratory system was operated on synthetic wastewater with acetate as sole carbon source. An efficient EBPR was obtained and mass balances over the anaerobic reactor showed a production of 1.45 g poly-b-hydroxyalcanoic acids (PHA), measured as chemical oxygen demand (COD), per g of acetic acid (as COD) taken up. Furthermore, phosphate was released in the anaerobic reactor in a ratio of 0.33 g phosphorus (P) per g PHA (COD) formed and 0.64 g... (More)
Enhanced biological phosphorus removal (EBPR) was studied in laboratory scale experiments as well as in a full scale EBPR process. The studies were focused on carbon source transformations, the use of nitrate as an electron acceptor and characterisation of the microflora. A continuous anaerobic/aerobic laboratory system was operated on synthetic wastewater with acetate as sole carbon source. An efficient EBPR was obtained and mass balances over the anaerobic reactor showed a production of 1.45 g poly-b-hydroxyalcanoic acids (PHA), measured as chemical oxygen demand (COD), per g of acetic acid (as COD) taken up. Furthermore, phosphate was released in the anaerobic reactor in a ratio of 0.33 g phosphorus (P) per g PHA (COD) formed and 0.64 g of glycogen (COD) was consumed per g of acetic acid (COD) taken up. Microscopic investigations revealed a high amount of polyphosphate accumulating organisms (PAO) in the sludge. Isolation and characterisation of bacteria indicated Acinetobacter spp. to be abundant in the sludge, while sequencing of clones obtained in a 16S rDNA clone library showed a large part of the bacteria to be related to the high mole % G+C Gram-positive bacteria and only a minor fraction to be related to the gamma-subclass of proteobacteria to which Acinetobacter belongs. Operation of a similar anaerobic/aerobic laboratory system with ethanol as sole carbon source showed that a high EBPR can be achieved with this compound as carbon source. However, a prolonged detention time in the anaerobic reactor was required. PHA were produced in the anaerobic reactor in an amount of 1.24 g COD per g of soluble COD taken up, phosphate was released in an amount of 0.4-0.6 g P per g PHA (COD) produced and 0.46 g glycogen (COD) was consumed per g of soluble COD taken up.



Studies of the EBPR in the UCT process at the sewage treatment plant in Helsingborg, Sweden, showed the amount of volatile fatty acids (VFA) available to the PAO in the anaerobic stage to be limiting phosphorous removal. Operating the primary clarifier to obtain an enhanced hydrolysis and fermentation of primary sludge was shown to generate extra VFA and improve EBPR. VFA were shown to be transformed to PHA in the anaerobic stage of the plant, giving a PHA production of 1.5 g COD per g VFA (COD). Phosphate-P was released in an amount of 0.31 g per g PHA (COD) produced. Nitrate was used as an electron acceptor for oxidation of stored PHA in the anoxic stage of the plant during simultaneous P-uptake. Approximately 30% of the P-uptake could be accounted for by this reaction. (Less)
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author
opponent
  • Dr la Cour Jansen, Jes, Denmark
organization
publishing date
type
Thesis
publication status
published
subject
keywords
activated sludge, nitrate, carbon source, PAO, polyphosphate accumulating organisms, enhanced biological phosphorus removal, EBPR, characterisation, Biotechnology, Bioteknik
pages
146 pages
publisher
Department of Biotechnology, Lund University
defense location
Lecture hall C, Center for Chemistry and Chemical Engineering
defense date
1997-11-14 13:15
external identifiers
  • other:ISRN: LUTKDH/TKBT--97/1034--SE
language
English
LU publication?
yes
id
235084ea-a81a-4ced-8533-a8444663eb6c (old id 29653)
date added to LUP
2007-06-14 08:38:19
date last changed
2016-09-19 08:45:08
@phdthesis{235084ea-a81a-4ced-8533-a8444663eb6c,
  abstract     = {Enhanced biological phosphorus removal (EBPR) was studied in laboratory scale experiments as well as in a full scale EBPR process. The studies were focused on carbon source transformations, the use of nitrate as an electron acceptor and characterisation of the microflora. A continuous anaerobic/aerobic laboratory system was operated on synthetic wastewater with acetate as sole carbon source. An efficient EBPR was obtained and mass balances over the anaerobic reactor showed a production of 1.45 g poly-b-hydroxyalcanoic acids (PHA), measured as chemical oxygen demand (COD), per g of acetic acid (as COD) taken up. Furthermore, phosphate was released in the anaerobic reactor in a ratio of 0.33 g phosphorus (P) per g PHA (COD) formed and 0.64 g of glycogen (COD) was consumed per g of acetic acid (COD) taken up. Microscopic investigations revealed a high amount of polyphosphate accumulating organisms (PAO) in the sludge. Isolation and characterisation of bacteria indicated Acinetobacter spp. to be abundant in the sludge, while sequencing of clones obtained in a 16S rDNA clone library showed a large part of the bacteria to be related to the high mole % G+C Gram-positive bacteria and only a minor fraction to be related to the gamma-subclass of proteobacteria to which Acinetobacter belongs. Operation of a similar anaerobic/aerobic laboratory system with ethanol as sole carbon source showed that a high EBPR can be achieved with this compound as carbon source. However, a prolonged detention time in the anaerobic reactor was required. PHA were produced in the anaerobic reactor in an amount of 1.24 g COD per g of soluble COD taken up, phosphate was released in an amount of 0.4-0.6 g P per g PHA (COD) produced and 0.46 g glycogen (COD) was consumed per g of soluble COD taken up.<br/><br>
<br/><br>
Studies of the EBPR in the UCT process at the sewage treatment plant in Helsingborg, Sweden, showed the amount of volatile fatty acids (VFA) available to the PAO in the anaerobic stage to be limiting phosphorous removal. Operating the primary clarifier to obtain an enhanced hydrolysis and fermentation of primary sludge was shown to generate extra VFA and improve EBPR. VFA were shown to be transformed to PHA in the anaerobic stage of the plant, giving a PHA production of 1.5 g COD per g VFA (COD). Phosphate-P was released in an amount of 0.31 g per g PHA (COD) produced. Nitrate was used as an electron acceptor for oxidation of stored PHA in the anoxic stage of the plant during simultaneous P-uptake. Approximately 30% of the P-uptake could be accounted for by this reaction.},
  author       = {Christensson, Magnus},
  keyword      = {activated sludge,nitrate,carbon source,PAO,polyphosphate accumulating organisms,enhanced biological phosphorus removal,EBPR,characterisation,Biotechnology,Bioteknik},
  language     = {eng},
  pages        = {146},
  publisher    = {Department of Biotechnology, Lund University},
  school       = {Lund University},
  title        = {Enhanced Biological Phosphorus Removal - Carbon Sources, Nitrate as Electron Acceptor, and Characterisation of the Sludge Community},
  year         = {1997},
}