KLAGSHAMN
WASTEWATER
TREATMENT PLANT
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Welcome to
Klagshamn Wastewater Treatment Plant
A large treatment plant
Why treat wastewater?
Klagshamn Wastewater Treatment Plant is situated on the
Spit of Klagshamn south of Malmö, and receives 230 litres of
wastewater per second, which is equivalent to 73 bathtubs
per minute. The water is received from the southern parts* of
Malmö and from the entire municipality of Vellinge. Approximately 70,000 residents are connected to the wastewater
treatment plant, which came into service in 1974.
The average Swede uses approximately 190 litres, or about
one bathtub full, of water every day. Water that is flushed
from toilets and washed down the drain is directed to our
treatment plants, where it is treated and then discharged
back into the natural water courses.
REDUCING SOCIETY’S ENVIRONMENTAL IMPACT
The goal of the Klagshamn plant is to ensure safe wastewater
treatment for residents in the neighbourhood, and for the
community in general. The best possible methods combined
with specialist competence ensure a sustainable treatment
process that is well adjusted to the ecological cycle, having a
minimum environmental impact.
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REMOVING NITROGEN AND PHOSPHORUS
The purpose of wastewater treatment is to protect the environment, animals and people from the harmful substances in
wastewater. For example, nitrogen and phosphorus can result
in eutrophication (enrichment of an ecosystem with nutrients,
typically compounds contain nitrogen and/or phosphorus)
in our waterways, causing algal blooms and other problems.
High amounts of organic substances in water result in the
depletion of oxygen, as oxygen is consumed when these
substances are degraded, and this can have serious effects
on many aquatic organisms.
Limhamn
The sewerage system
The Klagshamn Plant receives and treats wastewater
from the south-western part of the city of Malmö:
Limhamn and Klagshamn, and from the entire municipality of Vellinge, including the cities Vellinge, Höllviken
and Skanör/Falsterbo.
The sewerage system in Limhamn is combined, which
means that stormwater and sewage are transported in
the same system, while the municipalities of Klagshamn
and Vellinge have a duplicate system with separate
sewers for sewage and stormwater.
Wastewater treatment plant
Main pumping stations
Strandhem
Klagshamn
KLAGSHAMN
Gessie
Vellinge
Skanör/
Falsterbo
VELLINGE
Höllviksnäs
Main sewers
How is the treatment process
controlled?
The main task of the Klagshamn Plant is to handle and treat
wastewater in compliance with wastewater treatment regulations. A computerized control system is used to continuously monitor and regulate the treatment process, to ensure
that these requirements are met.
MALMÖ
Hammars Park
Trelleborg
Future challenges
Malmö and the region surrounding it are expanding. The number of residents is increasing, which means that new homes
are being built, placing increasing demands on wastewater
treatment plants. More stringent restrictions can also be
expected, as greater emphasis is being placed on protecting
the environment in our communities.
COMPUTERIZED MONITORING
Various meters are used to continuously measure the phosphorus concentration, the water flow and other parameters.
Wastewater samples from the different stages of the process are also analysed in the plant’s laboratory. The advantage of continuous monitoring is that it is possible to detect
changes in the treatment process as soon as they occur, and
to adjust the process accordingly. Laboratory analyses take
longer, but they are often more accurate than the meters.
CONTINUOUS IMPROVEMENTS
At our wastewater treatment plants we follow the general
trend in society of endeavouring to make use of the available
resources in the best possible way. Some of the environmentally friendly measures we have taken include advanced
control to reduce the electricity demand, optimal utilization
of the produced biogas, minimizing the amount of chemicals
used in the treatment process, and the recycling of nutrients.
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The treatment process
The Klagshamn Plant is divided into two parallel lines, which makes it less susceptible to disturbances. If there is
disruption in one line, the other will still be functioning. Another advantage of having two lines is that various trials
can be performed in one line while using the other as a reference to establish whether the trial has had a positive or
negative effect on the treatment process.
1. PUMPING STATIONS IN THE SEWERAGE NETWORK
Wastewater has to be pumped to the Klagshamn Plant. There
are 10 pumping stations along the main sewers from Malmö
and Vellinge. It is important that the wastewater flow is not
interrupted, and a team is therefore responsible for keeping
the pumping stations in good working order.
6. GRIT TREATMENT
The removed grit is pumped into a basin for dewatering, and
then transported by truck to landfill sites or other facilities.
7. PRE-PRECIPITATION
The trunk sewers from Hammars Park and Gessie pumping
stations to the Klagshamn Plant are used for equalization of
the wastewater flow into the plant. The wastewater level in
the sewers is used to control the inlet pumps at the plant and
at Strandhem Pumping Station.
Ferric chloride is added at the inlet to the grit removal basins
to increase the separation of phosphorus and organic material from the wastewater. The iron reacts with the phosphorus
and forms particles (sludge). The ferric chloride is stored as
a solution in special tanks. Two meters, one before and one
after the grit removal basin, measure the phosphorus concentration in the wastewater and the values obtained are used to
control the administration of ferric chloride.
3. INLET PUMPS
8. PRIMARY CLARIFICATION
2. FLOW EQUALIZATION
Wastewater is pumped into the plant by three screw pumps.
At normal water flows only one of the pumps is in operation,
but during high water flows it may be necessary to use all
three pumps.
Limhamn
Hammars Park
Strandhem
KLAGSHAMN
Klagshamn
Gessie
MALMÖ
In the primary clarifiers, particles with a density greater than
water sink to the bottom and form primary sludge.
9. DIVERSION OF PRE-PRECIPITATED SEWAGE
Under conditions of high water flow, such as heavy rain, the
influent flow to the plant is sometimes higher than the capacity of the biological treatment in the activated sludge basins.
Pre-precipitated wastewater from the grit removal stage can
then be diverted past the activated sludge basins in order to
reduce the hydraulic load in the treatment process, and prevent the vital microorganisms from being washed away.
10. ACTIVATED SLUDGE PROCESS
The first biological treatment stage is an activated sludge
process. Sludge with a high concentration of microorganisms
decomposes the organic material in the wastewater in an
Vellinge
aerobic (oxygen-rich) environment. The air is provided by air
blowers, and is regulated so that only the amount of air required for the process is added. Some of the basins are not
4. SEPARATION OF SCREENINGS
aerated in order to create a so-called anoxic environment,
The wastewater is passed through screensVELLINGE
where particles
Skannör/
where oxygen-intolerant microorganisms convert nitrate into
larger than 3 mm, called screenings, are removed. The volFalsterbo
nitrogen gas using the easily accessible carbon source in the
ume of screenings varies depending
on
the
weather
and
the
Höllviksnäs
wastewater. Oxygen content meters in the basins are used to
flow rate. Under dry weather conditions and low flow rates,
Trelleborg
regulate the air flow. Other instruments are used to measure
the screenings accumulate in the sewers. When it starts
to
the ammonia and sludge content in the basins.
rain, the rate of flow increases, and the screenings follow the
wastewater into the wastewater treatment plant. This places
a considerable hydraulic load on the plant for a short period.
11. SECONDARY CLARIFICATION
The screenings are washed and then transported to an incinIn the secondary clarifiers, the activated sludge is removed
eration facility.
from the wastewater. Most of the sludge is transferred back
to the activated sludge basins and is called return sludge. The
purpose of this is to maintain an adequate sludge content in
5. GRIT REMOVAL
the aeration basins. The remaining sludge, called waste actiSand and gravel are removed in aerated basins. Particles
vated sludge, is pumped to the sludge treatment.
lighter than water follow the wastewater further downstream, while heavier particles, such as sand, sink to the bottom. In order to remove particles of the desired size it is im12. OZONE REACTOR
portant to use the appropriate water velocity. Aeration helps
The conditions and design of the Klagshamn Plant favour the
in obtaining the correct velocity.
growth of a group of bacteria called filamentous bacteria in
the activated sludge system. These can impair the clarifica5
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4
FeCl3
5
8
3
1
2
6
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tion process, and the sludge is thus periodically treated in a
reactor where ozone and return sludge are mixed. Treatment
with ozone destroys the bacteria that are detrimental to the
clarification process.
13. PUMP HOPPER BEFORE POST-DENITRIFICATION AND
FILTRATION
Biologically treated wastewater and wastewater diverted
from the primary clarifiers is mixed in a pump hopper in such
a way that treatment of the diverted, and more contaminated, wastewater is prioritized. The wastewater is then pumped
to the denitrification and filtration stage. The capacity of the
pumps is limited, and when maximum capacity is exceeded,
the excess water spills directly into the outlet.
14. POST-DENITIRIFICATION
The wastewater is denitrified in order to remove nitrogen before it is discharged into the sea. Denitrification is a process
in which bacteria convert the nitrate formed in the activated
sludge basins into nitrogen gas, which is discharged to the atmosphere. A carbon source for the denitrification process is
added at the inlet of the basin. (The carbon source is stored in
large built-in tanks.) The process takes place in basins filled
with plastic that acts as carriers for the biofilm containing
the bacteria, a so called moving bed biofilm reactor (MBBR).
The carriers are kept in motion by slowly rotating mechanical
mixers. Screens are placed at the outlet of the basins to keep
the carriers in the basin.
15. FILTRATION
The final stage is filtration in five large sand filters. The water passes downwards through the filters, which consist of
sand and anthracite (dual media filters). This process is called
fine polishing, where particles in the water become trapped
in the pores between the grains of sand. If the separation of
phosphorus was not sufficiently effective in the grit removal
process (pre-precipitation), that is, if the phosphorus content
in the outlet water is too high, ferric chloride must be added
to the wastewater entering the filters. This process is called
post-precipitation.
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16. BACKWASH WATER RESERVOIR
The filtered wastewater is collected in a backwash water
reservoir and then transported to the outlet pipe. There is
always sufficient water in the backwash water reservoir to
wash the sand filters, if necessary.
17. BACKWASHING OF FILTERS
The sand filters gradually become clogged as particulate material accumulates. They must therefore be cleaned regularly
by washing and aerating them from below. The backwash water used for this is collected in an equalization basin, and then
returned to the inlet of the plant.
19. SLUDGE THICKENING
Raw sludge is the term used to describe the primary sludge
from the primary clarifiers and the excess sludge from the
secondary clarifiers. Raw sludge contains large amounts
of water. The water content is reduced in a gravity thickener where solid particles sink to the bottom to form sludge.
The sludge is pumped to the digesters and the liquid phase
is returned to the inlet of the plant. It is possible to separate
primary sludge and excess sludge. In this case, the sludge is
pumped through a raw sludge well and then through the thickener.
20. ANAEROBIC DIGESTION
18. OUTLET PIPE
Treated wastewater from the Klagshamn Plant is discharged
into Öresund, the Sound between Sweden and Denmark,
through a concrete pipe. The outlet point is 3.5 km from the
coast at a depth of about 10 meters. The water is discharged
through 10 spray nozzles.
The thickened sludge is led to the digesters, where part of the
organic material is degraded under anaerobic conditions, as
degradation is carried out by oxygen-intolerant bacteria. Digestion takes place in two stages at a temperature of 37 °C.
The sludge is heated in heat exchangers.
Po
EtOH
olymer
FeCl3
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21. BIOGAS HOLDER
During the digestion process biogas is formed, which consists
mainly of methane and carbon dioxide. The biogas is collected
and stored in a biogas holder to even out variations in the rate
of biogas production.
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24. DIGESTED SLUDGE THICKENING
The digested sludge is stored in a sludge thickener before dewatering. If required, the liquid phase from the thickener can
be returned to the plant inlet.
24. SLUDGE DEWATERING
22. MICROTURBINE FOR ENERGY PRODUCTION
The energy-rich biogas is burnt in a microturbine. The extracted electricity and heat are used at the wastewater treatment
plant, for example, for heating the sludge before anaerobic
digestion.
23. COMBINED BIOGAS BOILER
The microturbine has a limited capacity, and the biogas
is therefore also burnt in a combined biogas boiler. When
there is a shortage of biogas, this is compensated for by
natural gas. There are two boilers to ensure reliable energy
production.
The digested sludge is dewatered in centrifuges. A polymer
is added to the sludge before entering the centrifuges for
better separation between water and sludge, to achieve a
higher dry solids content in the sludge. The water obtained is
called reject water, and is returned to the inlet of the plant.
The sludge is stored temporarily in a tank, then removed from
the tank by screw conveyers to trucks and transported to the
sludge storage facility.
25. SLUDGE UTILIZATION
The dewatered sludge can be used in a soil product for parks
and urban environments, or as an organic fertilizer on agricultural land.
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Everyone plays an important role
Everyone can contribute to improving the environment by reducing the
demand/hydraulic load on wastewater
treatment plants. You can do this by
not wasting water, and by not disposing
of harmful substances down the drain.
If we all increase our “water awareness” the environment will benefit,
and we can preserve both the flora and
fauna in nature.
RETURN OLD MEDICINES
TO THE PHARMACY
It is very difficult, and sometimes
impossible, to decompose pharmaceuticals in a wastewater treatment
plant. Most pharmaceuticals simply
pass through the treatment plant and
end up in our water courses, where they
can have a highly detrimental effect
on aquatic organisms. Always return
expired and surplus medicines to a
pharmacy.
HAZARDOUS WASTE BELONGS
IN A RECYCLING CENTRE
Hazardous waste, such as paint, glue
and other chemicals (such as solvents),
should be taken to a recycling centre.
Never pour these down the drain or
throw them away in the refuse bin. You
can read more about recycling centres
and hazardous waste on SYSAVs website: www.sysav.se .
GREASE CLOGS THE PIPES
Grease clogs pipes and promotes the
growth of microorganisms that interfere with the wastewater treatment
process. A good tip is to wipe your frying pan with kitchen paper and throw it
in the bin before washing the pan.
KEEP A WASTE BIN IN YOUR BATHROOM
We frequently have problems at
treatment plants caused by “foreign
objects” such as tampons, sanitary
towels, condoms, cigarette ends, snuff,
hair, cotton swabs and cat litter. These
should be thrown in a bin instead. If you
don’t already have one, place a
small pedal bin in your bathroom.
WHAT YOU DO MATTERS
Wastewater treatment, more
than most other environmental
areas, is directly influenced by
what we do as individuals. We
can all help to save our natural
resources through a few simple
measures.
t the toilet is
Remember tha
posal unit.
not a waste dis
you should
The only things
toilet are poo,
flush down the
aper.
wee and toilet p
Glossary
ACTIVATED SLUDGE PROCESS:
A biological treatment stage in which
microorganisms decompose organic
material and convert ammonia into
nitrate and nitrogen gas
AEROBIC: Containing oxygen
ANAEROBIC: Being completely devoid
of oxygen
ANAEROBIC DIGESTION: Anaerobic
biological decomposition of organic
material resulting in the production
of biogas (mainly methane)
ANOXIC: Containing oxygen only in the
form of compounds such as nitrite,
nitrate and/or sulphate
BOD: Biochemical Oxygen Demand or
Biological Oxygen Demand, a meas-
10
ure of the content of biodegradable
substances in the wastewater
CLARIFICATION: Settling of heavy
particles in the water by gravity
DENSITY: Mass per unit volume,
g/cm or kg/m
3
3
EUTROPHICATION: A process in which
excessive amounts of nutrients, for
example, phosphorus and nitrogen,
are deposited in soil or water
OVERFLOW: During periods of high
water flow, the flow of wastewater
sometimes exceeds the capacity of
the plant, and incoming water has to
be diverted past some stages of the
treatment process
POST-PRECIPITATION: Chemical
precipitation of residual phosphorus
after the biological treatment
PRE-PRECIPITATION: Chemical precipi-
tation of phosphorous in the primary
treatment
SEWAGE: Wastewater from households and industrial processes
SLUDGE: The material produced dur-
ing wastewater treatment, consisting
of decaying products in the wastewater
STORMWATER: Rainwater and snow
melt run-off
FOTO: LINDA BERGLUND
Technical data
Plant data
THE SEWERAGE SYSTEM
Malmö uptake area 12 km
Total length of sewers 180 km
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Pumping stations for wastewater 12
Pumping stations for stormwater 3
Number of stormwater storage tanks 6
Percentage of combined sewerage system 32%
Percentage of duplicate sewerage system 65%
Percentage of active duplicate sewerage system 3%
Sewerage system overflows 7
DESIGN DATA
Population equivalents 90,000
Qmax 3,000 m3/h
Qmax to biological treatment 1,800 m3/h
Qmax to post-treatment 1,800 m3/h
INCOMING AND OUTGOING
QUANTITIES DURING 2015
BOD7
Incoming (kg/d)
Outgoing (kg/d)
3,600 93
97 4
790 240
Total phosphorus
Total nitrogen
Flow 21,055 m3/d
EFFLUENT REQUIREMENTS
BOD7 Total phosphorus Total nitrogen 10 mg/l
(monthly average)
0.3 mg/l
(monthly average)
12 mg/l
(annual average)
PRIMARY TREATMENT
POST-TREATMENT
Screens
2 with 3 mm mesh
2 with 2 mm mesh
MBBR reactor
Number 4
Volume 4 x 275 m3
Filling degree 36%
Screenings washing
Lines 2
Grit removal basins
Number 2
Volume 2 x 200 m3
Primary clarifiers
Number 4
Area 4 x 250 m2
Volume 4 x 550 m3
Tanks for chemical
precipitation
Number 2
Volume 2 x 28 m3
Dual media filters
Number 5
Area 5 x 44 m2
Tanks for chemical
precipitation
Number 1
Volume 23 m3
Tanks for carbon source
Number 3
Volume 3 x 23 m3
BIOLOGICAL TREATMENT
SLUDGE TREATMENT
Aeration basins
Thickeners
Number Volume Number Area
Volume 2
2 x 2,200 m3
Secondary clarifiers
Number 8
Area 8 x 170 m2
Volume 8 x 612 m3
Digesters
Number
Volume Centrifuges
Number
Capacity 2
2 x 493 m2
2 x 133 m3
2
2 x 1,750 m3
2
2 x 20 m3/h
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KLAGSHAMN WASTEWATER TREATMENT PLANT • Issue 01 2016.09 • Photo framsida: Linda Berglund • llustration: Millimeter
VA SYD supplies fresh drinking water, treats wastewater and
is responsible for waste management for over half a million
people. We encourage you to drink tap water, sort your household waste, and be careful about what you dispose of down
3041 0140
TRYCKSAK
Customer Service tel. 040-635 10 00
the drain. Together we can actively contribute to sustainable
[email protected]
urban development. For the environment, near you.
www.vasyd.se