1. Prevention of filaments with aluminium or ozone at Klagshamn WWTP? Marika Wennberg*, Ulf Nyberg* and Karin Jönsson** * VA SYD **Lund University

2. Problem Filamentous microorganisms Solution Aluminium or ozone? Control of sludge age?

3. AluminiumOzone

4. Dimensioned p.e. 90 000 Actual p.e. 70 000 Actual flow 800 m 3 /h Discharge limits BOD 7 10 mg/l * Tot-P0.3 mg/l * Tot-N12 mg/l ** * monthly average ** annual average

5. Klagshamn WWTP

6. Effects of filaments

7. Aluminium treatment  Chemical: PAX-15 (polyaluminium chloride)  Dose: 1.2 g Al/m 3  Simple technical equipment  Treatment performed 2006-2009  1-3 months  Focus on DSVI (ml/g)

8. Four periods of Al-treatment – four different outcomes

9. Ozone treatment  Full-scale test, performed in one of the two lines  2.5-months treatment  Dose: 550 g O 3 /h 0.006 g O 3 /g MLSS Process parameters  MLSS-concentration: 3 g/L  Sludge age: 20 days at start-up  Water temperature: 14°C at start-up

10. Process layout

11. Ozone makes a difference

12. No ozone Ozone

14. Improved settling properties

15. Effects on nitrification  Lower nitrification rate (mg NH 4 -N/gVSS,d) in experimental line during lab tests  Higher concentrations of NH 4 -N in secondary effluent in experimental line

16. Control of sludge age

17. Estimated costs Operating cost Investment cost Total cost Ozone48 000250 000298 000 Aluminium32 0005 00037 000 Removal of floating sludge 300 000 (SEK/year)

18.  Dosing of Aluminium was and was not…  Ozonation was…  Controlling aerobic sludge age was not… …an option to prevent filamentous growth at Klagshamn WWTP. What did we learn?

19. Acknowledgements Kemira Air Liquide Operational and laboratory staff at Klagshamn WWTP