waste water treatment in sweden

8/8/2019 Waste Water Treatment in Sweden

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Waste Water Treatment in

Sweden

Kerstin Mundt 2006


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History of waste water treatment

1920: all towns had waste water piping but only one had

treatment

1950s biological treatment (to reduce bad smell)

1955: law to treat waste water

1960s: problem with over fertilization in lakes caused by

phosphorus. Treatment started

1970s finacal aid to build phosphorus treatment

Around 1985: problem with nitrogen, treatment started


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History of waste water treatment


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Improvement of treatment


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Sweden today

2000 public waste water treatment plantswith 7.7 milj. people connected

1.3 milj. people have private treatment

Pollution of water courses fromwastewater on the same level as 100years ago

Problem 1: Treatment in small plants and privatetreatment (phosphorus)

Problem 2: Sludge treatment


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Level of treatment today


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Average degree of purification

Nitrogen BOD

54%

Phosphorus

95% 96%


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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


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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)


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Treatment of BOD

Biological aerobic treatment

Problem in north part where it is coldNot needed because of much water and few people.

EU-regulation says all water below 1500 mmust be treated.


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Treatment of phosphorus

Problem in fresh water where it isregulating growth.

Chemical treatment with metal salt(Biological treatment possible, but hard to conrol)

H

ard regulation compared to EULimits in Sweden: 0.3-0.5 mg/l (average outlet 0.3 mg/l)

EU-regulation: 1-2 mg/l


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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


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Phosphorus vs Nitrogen

Discussion about Baltic Sea: Improvement

of nitrogen treatment unnecessary?

-Fresh water: senstive for phosphorus not nitrogen

-Studies show improvements caused by nitrogentreatment but critics has other explainations

-Waiting for conclusion


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Himmerfjrden waste water

treatment plant


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Location


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Facts

Run by company, SYVAB, owned by six

municipalties

Started 1974. Today top modern treatment

250 000 persons connected + 35 000 pe fromindustry

Average flow 110 000 m3 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)


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment

Deposit


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Treatment


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Treatment


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Treatment


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Treatment


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Treatment


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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


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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 forenergy forest and real forest, burning

Long lasting solution and regulations is needed


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Conclusions

Good public waste water treatment

Small treatment plants and private

treatment a problem Rules for how sludge should be treated is

needed

waste water treatment in sweden

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