Sludge handling in Bottrop

Sludge handling in Bottrop
Dr.-Ing. K.-Georg Schmelz
Emschergenossenschaft / Lippeverband
Essen, Germany

Sludge handling in Bottrop
Structure
1 Introduction
2 Sludge network system
3 Production of fuels on a sewage sludge basis
- coal-polymer conditioning
- trials using different high calorific fractions
- shredder fluffing agglomerate-polymer conditioning
4 Sludge incineration in fluidised bed furnances
5 Summary and conclusions

Where we are working

Where to find our wastewater treatment plants

EMSCHERGENOSSENSCHAFT and LIPPEVERBAND
two water associations with wide experience
• The EMSCHER Association founded in 1899
• The LIPPE Association founded in 1926
• EG and LV are two of the largest water associations
in Germany
Total area:
Wastewater:
4 248 square kilometres
approx. 6 million PE

Sludge pressure pipelines
8 km
20 km
Folie 6

2 Sludge network system
• Three WWTPs are connected:
- Alte Emscher Duisburg: 500,000 PE
- Emscher Mouth TP: 2,400,000 PE
- Bottrop WWTP: 1,340,000 PE
• The sludge of the three WWTPs is treated at the
Central Sludge Treatment Plant in Bottrop
• 60,000 tons dry matter per year
• Conditioning, dewatering, incineration

Digestion
Incineration
Waste Water
Treatment
River Emscher
Conditioning 1
adding coal
Conditioning 2
adding polymers
+ Dewatering

3 Production of fuels on a sewage sludge basis
• The production of fuels from sewage sludge is caused
by history
• The wastewater in the Emscher area was characterised
by coal loadings from the mining companies
• So the sewage sludge had a high fine coal portion
(up to 30 % of the dry matter)
• The dewaterability on filter presses was very good
(up to 50 % dry solids in the filter cake)
• The dewatered sludge could be used as a fuel in
a power station in the neighborhood

3 Production of fuels on a sewage sludge basis
• Since the late seventies of the last century the coal
mining in the Emscher area decreased rapidly
• The content of fine coal in the wastewater also
decreased
• In the early eighties coal admixture facility
• Continue producing a fuel from sewage sludge
• Incineration in 2 new fluised bed furnances

3 Production of fuels on a sewage sludge basis
- previous system (coal-polymer conditioning)
• For an autonomous incineration in the fluised
bed incinerators the dewatered sludge must have:
- calorific value: 4,400 kJ/kg (wet material)
- water content: 55 – 60 % by weight
- Ashes content: 45 % by weight
• So it was necessary to add 20 – 25 % fine coal
• mixture of hard coal and lignite
• Particle size: 0 – 2 mm

3 Production of fuels on a sewage sludge basis
- previous system (coal-polymer conditioning)
Conditioning 1 Conditioning 2
DS = 20 %

3 Production of fuels on a sewage sludge basis
- trials with various high calorific value fractions
• Aim: replace the primary energy carrier coal
• trials using other high calorific value materials
- recycling materials (e. g. plastics)
- renewable raw material (e. g. sawmill waste)
• a lot of materials were suitable for conditioning
and dewatering
• best results we got with shredder fluffing
agglomerate (made from old cars)
see the next slides

Recycling of old cars: the situation today
Liquids out/
Demontage
Shredder
Waste
• Let out all liquids
• Take away battery, tyres
• Take out spare parts
• Pressing the body
Spare parts
Recycling
Scrap steel
• main grinding
• iron separation
• non-iron separation
Iron scrap
Non iron metals
SHF
(Shredderheavy
fraktion)
50% 50%
50% 50%
SLF
(Shredderlight
fraktion)
About 20% of
the weight of the car
are going to landfill
From 2015 in the EU only 5% are allowed to be discharged

The Volkswagen-SiCon-Process for Shredderfluffing
Treatment
Shredder-Material
Shredder-Material
Main process of treatment
Fe NE Raw granular Raw fluffing Raw sand
Special treatment for different costumers
granular fluffing sand rest
disposal
Recycling (e.g. PVC)
NE-metal production, ...
Sewage sludge dewatering, ...
Blast furnance, ...

3 Production of fuels on a sewage sludge basis
We have the following requirements to the material:
• a good dewatering result (>40 % DS)
• a calorific value of more than 4,400 kJ/kg wet sludge
• no additional load in the filtrate water
• no additional emissions from the incineration
• no worsening of the ashes
• as possible no changes of the existing system
• low costs
• availability over a long period in future
• the existing disposal ways must be possible

Delivery and mixing of the conditioning products
Mixing basin situated in by-pass
Mixing basin
at time
in future

3 Production of fuels on a sewage sludge basis
- new system (SA-polymer conditioning)
Shredder
agglomerate
X

Filter cake with Shredder Fibres

3 Production of fuels on a sewage sludge basis
- new system: results from the large scale trial
• Dewatering result could be improved
(+2 to +5 %-points!)
• The fluffing material can be mixed into the sludge
nearly as easy as the coal (dust)
• The stripping behaviour of the filter cake from
the filter presses was very good
• combustion performance: no changes, normal
• filtrate water: no higher concentrations
• flue gas: no increased emissions

4 Sludge incineration
fluidized-bed furnance
steamer
400°C, 40 bar
2 x 7.0 t/h
waste gas washing
chimney
sludge
2 incinerators
each 7.0 t/h
turbine
2.7 MW
filter for
ashes
washing-zone for
heavy metals

Schlammanfall

4 Sludge incineration and disposal of ashes
• in the past: ashes are used to produce mining mortar
for filling underground hollow spaces from mining
• today: building material for road construction
• in future: store the phospherous-rich ashes in monodump-sites
to recover the phospherous later (when
the recycling methods are further developed and
economic)

5 Summary and conclusions
• Emschergenossenschaft and Lippeverband are
two of the largest water associations in Germany
• the production of fuels from sewage sludge is
caused by history (coal mining)
• the content of fine coal in the wastewater (and the
sludge) makes it possible to produce a fuel for
power stations
• coal mining decreased rapidly since the seventies
• from the eighties fine coal must be added to the
sludge to go on in fuel production from sludge
• the aim today is to replace the coal through
recycling or renewable raw materials

5 Summary and conclusions
• the use of shredder fluffing agglomerate for
conditioning seems to make it possible to replace
the coal by a recycling product
• Advantages for both sides:
- the car-industry
- Emschergenossenschaft

Thank you for your attention!