Bulking sludge causes major problems in waste water treatment plants that deal with biological nutrient removal in activated sludge processes. Bulking sludge is caused by filamentous bacteria, which have a negative impact on the sludge settling properties.Himmerfjärden wastewater treatment plant suffers from this type of problem with bulking sludge which creates a stable layer at the surface that does not settle in the clarifier.In order to solve this problem, on site generated ozone was used to decrease the amount of filamentous bacteria in the return activated sludge flow. Ozone is a strong oxidant is suitable for non-specific bulking control. It stresses the filamentous bacteria causing inactivation through cell wall disintegration.The ozone treatment resulted in decreased abundance of filamentous bacteria. Ozone treatment of the recycled activated sludge improves the settling properties of bulking sludge, without interfering with other important microbiological processes e.g. nitrification.
Contents
1 INTRODUCTION
2 OZONE
2.1 Physical chemistry
2.2 Ozone generation
3 METHODS
3.1 WWTP description
3.2 Description and operation of experimental plant and reactors
3.4 Microscopic analysi
3.5 Analysed parameters
4 RESULTS
4.1 Enhancement of sludge quality
4.2 Microscopic studies of filamentous microorganisms
4.3 Influence on the return activated sludge
4.4 Treatment results and effects on RAS
4.5 The nitrifying community
5 DISCUSSION
5.1 Effects of ozone treatment
5.2 Practical consideration for ozone generation
6 REFERENCES
Author: Wijnbladh, Erik
Source: Uppsala University Library
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