Impact of activated sludge ozonation on filamentous bacteria viability and possible added benefits

• Ozone was applied to return activated sludge in full-scale to study how ozone impacts filamentous bacteria viability (Live/Dead®). Additionally, the ozonated sludges were subjected to anaerobic digestion trials and analysis of micropollutants. Ozone treatment (3-4.8 g O3/kg TSS) improved the settling properties of the sludge by lowering the diluted sludge volume with 7-35%. Ozone inactivated filamentous bacteria outside the floc structures and the fraction of inactivated filaments increased with an increasing ozone dose. It was observed that ozone treatment may act selectively towards different types of filaments. With respect to the two dominating morphotypes present, Type 0041 filamentous bacteria were found to be more resistant to ozone attack than Microthrix parvicella. Thus, higher ozone doses may be required to mitigate sludge bulking caused by Type 0041 filaments. No effects could be discerned by ozone addition on neither the methane production of the sludge nor on the concentrations of micropollutants analysed for this study. The lack of effect on both methane production and micropollutant removal was deemed to be caused by insufficient ozone doses.

• Ozone was applied to return activated sludge in full-scale to study how ozone impacts filamentous bacteria viability (Live/Dead®). Additionally, the ozonated sludges were subjected to anaerobic digestion trials and analysis of micropollutants. Ozone treatment (3-4.8 g O3/kg TSS) improved the settling properties of the sludge by lowering the diluted sludge volume with 7-35%. Ozone inactivated filamentous bacteria outside the floc structures and the fraction of inactivated filaments increased with an increasing ozone dose. It was observed that ozone treatment may act selectively towards different types of filaments. With respect to the two dominating morphotypes present, Type 0041 filamentous bacteria were found to be more resistant to ozone attack than Mictrothrix parvicella. Thus, higher ozone doses may be required to mitigate sludge bulking caused by Type 0041 filaments. No effects could be discerned by ozone addition on neither the methane production of the sludge nor on the concentrations of micropollutants analysed for this study. The lack of effect on both methane production and micropollutant removal was deemed to be caused by insufficient ozone doses.

Subject headings

NATURVETENSKAP  -- Kemi -- Annan kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Other Chemistry Topics (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Miljöbioteknik -- Vattenbehandling (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Environmental Biotechnology -- Water Treatment (hsv//eng)

Publication and Content Type

art (subject category)

ref (subject category)