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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

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Production of fly ash – 20 000 ton a year

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Fly ash and bottom ash.

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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

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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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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

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Pilot surfaces – 2 different construction methods Every surface is 40*40 m2 All together 320 m2

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Broken glass a gas drainage

Macadam (gravel) as top drainage

Lysimeters – to collect leachate. We had 12 lysimeters in 2 levels

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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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novem

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septe

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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.

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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??

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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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Lysimeter 1

Lysimeter 4

Lysimeter 5

Lysimeter 7

Lysimeter 10

Lysimeter 11

Lysimeters in the middle of the ash layer Only ash around

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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

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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