WWTP MANAGEMENT AND TREATMENT in Sweden.ppt

WASTEWATER TREATMENT TECHNOLOGY AND APPLICATION

1. Waste Water Treatment in
Sweden
Kerstin Mundt 2006

2. History of waste water treatment
•1920: all towns had waste water piping but only one had
treatment
•1950’s biological treatment (to reduce bad smell)
•1955: law to treat waste water
•1960’s: problem with over fertilization in lakes caused by
phosphorus. Treatment started
•1970’s finacal aid to build phosphorus treatment
•Around 1985: problem with nitrogen, treatment started

3. History of waste water treatment

4. Improvement of treatment

5. Sweden today
•2000 public waste water treatment plants
with 7.7 milj. people connected
•1.3 milj. people have private treatment
•Pollution of water courses from
wastewater on the same level as 100
years ago
•Problem 1: Treatment in small plants and private
treatment (phosphorus)
•Problem 2: Sludge treatment

6. Level of treatment today

7. Average degree of purification
Nitrogen BOD
54%
Phosphorus
95%
96%

8. Laws
The Environmental Code
-Ecological harmful activity
-General consideration rules (knowledge, technology,
location, raw materials and energy)
”VA-lagen” (water and sewage law)
-All municipals have to take care of water supply and waste
water in urban areas
EU-directives
-At least secondary, i.e. biological treatment

9. Permission for Plants over 2000 pe
–How much water that can be let out
–Level of phosphorus, nitrogen and BOD in
outgoing, cleaned water
Permissions are set individual depending on
recipient. Mean values in Sweden :
Phosphorus 0.5 mg/L
BOD 15 mg/L
Nitrogen 10-15 mg/L (depending on size and location)

10. Treatment of BOD
•Biological aerobic treatment
•Problem in north part where it is cold
Not needed because of much water and few people.
•EU-regulation says all water below 1500 m
must be treated.

11. Treatment of phosphorus
•Problem in fresh water where it is
regulating growth.
•Chemical treatment with metal salt
(Biological treatment possible, but hard to conrol)
•Hard regulation compared to EU
Limits in Sweden: 0.3-0.5 mg/l (average outlet 0.3 mg/l)
EU-regulation: 1-2 mg/l

12. Treatment of nitrogen
•Nitrogen is a problem mainly in salt water
•Biological treatment. Nitrification aerobic,
denitrification anaerobic
•Problem with EU-regulation
-Definition of sensitive water and where treatment is
needed

13. Phosphorus vs Nitrogen
Discussion about Baltic Sea: Improvement
of nitrogen treatment unnecessary?
-Fresh water: senstive for phosphorus not nitrogen
-Studies show improvements caused by nitrogen
treatment but critics has other explainations
-Waiting for conclusion…

14. Himmerfjärden waste water
treatment plant

15. Location

16. Area of uptake

17. Facts
•Run by company, SYVAB, owned by six
municipalties
•Started 1974. Today top modern treatment
•250 000 persons connected + 35 000 pe from
industry
•Average flow 110 000 m
3
per day
•Purification levels (2003):
–90% of nitrogen (4.1 mg/l)
–95% of phosphorus (0.31 mg/l)
–97 % of BOD (6.7 mg/l)

18. Treatment

19. Treatment

20. Treatment

21. Treatment

22. Treatment

23. Treatment

24. Treatment

25. Treatment

26. Treatment

27. Treatment

28. Treatment

29. Treatment

30. Treatment
Deposit

31. Treatment

32. Treatment

33. Treatment

34. Treatment

35. Treatment

36. Treatment

37. Use of sludge
•26 000 ton/year (2003)
6100 ton dry substance
–80% cover landareas (deposits, parks etc.)
–20% deposit (forbidden since 2005)
–1.5 % fertilizing of forest (test)
–0.5 % burned (test)
•Need to find long lasting solution

38. Sludge problem in Sweden
•1 000 000 ton sludge produced every year
–2.8 % phosphorus, 3.8 % nitrogen  good fertilizer
•Fertilizer on fields best use from ecological and
recycling point of wiew
–Problems: chemicals, heavy metalls
–Limits set by Swedish environmental protection agency
–How do we know what is harmful? (flame retardants etc)
•Examples of alternatives: Biosoil, fertilizer for
energy forest and real forest, burning
•Long lasting solution and regulations is needed

39. Conclusions
•Good public waste water treatment
•Small treatment plants and private
treatment a problem
•Rules for how sludge should be treated is
needed