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Improving post-sedimentation at Henriksdal municipal wastewater treatment plant.
KTH, School of Biotechnology (BIO).
2013 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Förbättring av eftersedimenteringen vid Henriksdagls kommunala avlooppsreningsverk (Swedish)
Abstract [en]

Dosgin of two different chemical amendments was evaluated to counter problems with poorly settling activated sludge in separate treatment trains at Henriksdal wastewater treatmen plant, Stockholm. Flocculating cationic polyacrylamide (CPAM) was added to the secondary clarifiers to evoke an immediate improvment of sludge settling. Fine chalk (Otical 20) was added to the aeration baisins t improve the activated sludge floc structure and enable more efficient nitrogen removal due to the alkalinity increasing property of the substance.

Reductions of SVI and turbidity were confirmed in lab scale with dose concetnrations of 1-2 mg/l of CPAM. Dose concentrations of 1-3 mg/l in the treatment plant showed no improvement of the quality of the effluent, while ability to control the height of the sludge blankets was proven towards the end of the study at extremely high SVI (>250 ml/g) and high amount of filaments in the activated sludge.

Dosing of Optical 20 was inconclusive regarding improvement of floc structure and settling properties of the activated sludge, likely die to an insufficient average dose concentration. A slight increase of the alkalinity in the biological treatment stage was possibly shown towards the end of the dosing period.

Revised dosing strategies for full scale applications and a rough financial evaluation of the two methods conclude the report.

Place, publisher, year, edition, pages
Keyword [en]
post-sedimentation, wastewater treatment, flocculation, sedimentation, filamentus bacteria, nitrification, polymer adition, Optical20
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-149936OAI: diva2:744706
Available from: 2015-04-17 Created: 2014-08-28 Last updated: 2015-09-23Bibliographically approved

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