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Use of Fly ash from KKAB, Sweden Sealing a landfill with only fly ash
Alternative title slide
M.Sc.Civ.Eng Kristina Hargelius, Environmental consultant in Ramböll Sweden AB
Recycled paper – gives us perfect fly ash
2
Production of fly ash – 20 000 ton a year
3
Fly ash and bottom ash.
4
The fly ash is a non hazardous product – includes metals -SiO2 -CaO -Al2O3 -K2O Similar substances as in cement.
The bottom ash contains heavy metals
Chemical contents of the KKAB fly ash is similar to puzzolana cement
SiO2
Al2O3
CaO
Fe2O3
K2O
MgO
MnO
Na2O
P2O5
TiO2
Sum
22
11
56
2
0,8
1,6
0,095
0,4
0,3
0,3
95
5
% TS
% TS
% TS
% TS
% TS
% TS
% TS
% TS
% TS
% TS
% TS
Limit for inert material Average for KKABs Fly ash
L/S 0,1 L/S 10 L/S 0,1 L/S 10
mg/l mg/kg TS mg/l mg/kg TS
As 0,06 0,5 0,001 0,01
Ba 4 20 1,0 61,5
Cd 0,02 0,04 0,000 0,001
Cr 0,1 0,5 0,072 0,138
Cu 0,6 2 0,005 0,043
Hg 0,002 0,01 0,000 0,000
Mo 0,2 0,5 0,278 0,155
Ni 0,12 0,4 0,000 0,005
Pb 0,15 0,5 0,015 0,644
Sb 0,1 0,06 0,000 0,003
Se 0,04 0,1 0,001 0,002
Zn 1,2 4 0,016 0,438
Cl 460 800 32 321
SO4 1500 1000 62 55
F 2,5 10 1,7 28
DOC 160 500 7,8 38
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Geotechnical and chemical tests of the fly ash
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There were no good results at the laboratories. The hardening ash is non-plastic.
Fly ash from KKAB - compressive strength after 6 hours - from a pre study
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0
50
100
150
200
250
300
350
400
450
500
0 1 2 3 4 5 6 7 8
skju
vhål
lfas
the
t kP
a
deformation %
w=29%, 1,06t/m³ w=47%, 1,48t/m³
The ash mine of Rome. 3000 – 2000 years ago they began to use Pozzolana ash.
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Puzzolana ash has been used for more than 2000 years – Pantheon temple in Rome
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Drilling in ash layers from nearly ten years of ash deposing to find the groundwater table
• No water found
• The ash was powder dry
down to a depth of 10 m
below surface
• Some fly ash was left
behind in an airtight
sampling bag
• 5 days later the ash was
hard as concrete
11
Pilot surfaces – 2 different construction methods Every surface is 40*40 m2 All together 320 m2
12
Broken glass a gas drainage
Macadam (gravel) as top drainage
Lysimeters – to collect leachate. We had 12 lysimeters in 2 levels
13
A pilot surface was established as a terracing
surface with crushed glass as gas drainage
Content slide
Lysimeters filled with macadam (gravel) and sand in the middle of the ash layer
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Precipitation in the form of snow can be moved away
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The last layer Top soil. We pressed the system, by not take notice of
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0
20
40
60
80
100
120
novem
ber
decem
ber
januari
febru
ari
mars
april
maj
juni
juli
augusti
septe
mber
okto
ber
novem
ber
decem
ber
januari
febru
ari
mars
april
2009 2010 2011
Rainfall nov 2009 to april 2011
Nederbörd (mm)
High lysimeters at - 0,5 m level
Low lysimeters at - 1,0 m level
Pumping water from the lysimeters
• During 1,5 years the 12
lysimeters has collected 4,2
litres all together
• Every lysimeters surface is 0,2
m2
• The permeability is approx. 1,2
l/m2 a year
• During the last test, water was
only collected by one of the
lysimeters.
20
Results during 1,5 year
• The guidelines concerning sealing is following
• A landfill for non hazardous waste - max permeability 50 l/m2 a year
• A landfill for hazardous waste - max permeability 5 l/m2 a year
Dates for sampling of
water from the
lysimeters
(The first test)
2010-04-21 2010-10-25 2011-05-09 2011-09-15
Total volume (l) from 12
lysimeters 3,75 0,3 0,05 0,15
Equivalent to liter/m2 a
year 6,25 0,50 0,09 0,25
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Testing the function of the lysimeters – Was it too good to be true??
22
We pumped water with a dye tracer backwards into the system
Peristaltic pump
We pumped water into the dry lysimeters, to be sure that nothing was broken.
Amount of water in the lysimeters after 2 years A leak has occurred in the gas drainage layer
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0
1
2
3
4
5
6
Lysimeter 1
Lysimeter 4
Lysimeter 5
Lysimeter 7
Lysimeter 10
Lysimeter 11
Lysimeters in the middle of the ash layer Only ash around
0
1
2
3
4
5
6
Lysimeter 2
Lysimeter 3
Lysimeter 6
Lysimeter 8
Lysimeter 9
Lysimeter 12
Lysimeters in the bottom layer Crushed glass
Levels of metals and salts in the lysimeter water. Some thing changes
24
0
10000
20000
30000
40000
50000
60000
70000
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Halt
er i
lysim
ete
rvatt
en
Ca (mg/l)
Fe (mg/l)
K (mg/l)
Mg (mg/l)
Na (mg/l)
As (μg/l)
Ba (μg/l)
Cd (μg/l)
Co (μg/l)
Cr (μg/l)
Cu (μg/l)
Hg (μg/l)
Mn (μg/l)
Ni (μg/l)
Pb (μg/l)
Zn (μg/l)
Sulfat
Klorid
Konduktivitet
Alkalinitet
Al (μg/l)
K Al
Kond
Zn Na
Cr
What is the next step? Reclassification
• The whole landfill will be sealed
with the fly ash.
• The waste classification is now
“Non-hazardous” and we are
applying for a reclassification to
“Inert waste”.
• The case is in the process
• On Monday we will go up to
Mariestad and dig up part of the
surface for to locate the cause of
the leak
• To be continued…….
Content slide, two columns with image
THANKS