Image size: 7,94 cm x 25,4 cm Use of Fly ash from KKAB, Sweden Sealing a landfill with only fly ash 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. The fly ash is a non hazardous product includes metals -SiO 2 -CaO -Al 2 O 3 -K 2 O Similar substances as in cement. The bottom ash contains heavy metals 4
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 % TS % TS % TS % TS % TS % TS % TS % TS % TS % TS % TS 5
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 SO 4 1500 1000 62 55 F 2,5 10 1,7 28 6 DOC 160 500 7,8 38
Geotechnical and chemical tests of the fly ash There were no good results at the laboratories. The hardening ash is non-plastic. 7
skjuvhållfasthet kpa Fly ash from KKAB - compressive strength after 6 hours - from a pre study 500 450 400 350 300 250 200 150 100 50 w=29%, 1,06t/m³ w=47%, 1,48t/m³ 0 0 1 2 3 4 5 6 7 8 deformation % 8
The ash mine of Rome. 3000 2000 years ago they began to use Pozzolana ash. 9
Puzzolana ash has been used for more than 2000 years Pantheon temple in Rome 10
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 Macadam (gravel) as top drainage Broken glass a gas drainage 12
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
Lysimeters filled with macadam (gravel) and sand in the middle of the ash layer 15
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Precipitation in the form of snow can be moved away 17
The last layer Top soil. We pressed the system, by not take notice of 18
november december januari februari mars april maj juni juli augusti september oktober november december januari februari mars april Rainfall nov 2009 to april 2011 120 100 High lysimeters at - 0,5 m level 80 60 40 Nederbörd (mm) 20 0 Low lysimeters 2009 at - 1,0 m level 2010 2011 19
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 m 2 The permeability is approx. 1,2 l/m 2 a year During the last test, water was only collected by one of the lysimeters. 20
Results during 1,5 year Dates for sampling of water from the lysimeters Total volume (l) from 12 lysimeters Equivalent to liter/m 2 a year (The first test) 2010-04-21 2010-10-25 2011-05-09 2011-09-15 3,75 0,3 0,05 0,15 6,25 0,50 0,09 0,25 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 21
Testing the function of the lysimeters Was it too good to be true?? Peristaltic pump We pumped water into the dry lysimeters, to be sure that nothing was broken. We pumped water with a dye tracer backwards into the system 22
Amount of water in the lysimeters after 2 years A leak has occurred in the gas drainage layer 6 5 4 3 2 1 0 Lysimeters in the middle of the ash layer Only ash around Lysimeter 1 Lysimeter 4 Lysimeter 5 Lysimeter 7 Lysimeter 10 Lysimeter 11 6 5 4 3 2 1 0 Lysimeters in the bottom layer Crushed glass Lysimeter 2 Lysimeter 3 Lysimeter 6 Lysimeter 8 Lysimeter 9 Lysimeter 12 23
Halter i lysimetervatten Levels of metals and salts in the lysimeter water. Some thing changes 5000 70000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 Zn K Al Kond Na Cr 60000 50000 40000 30000 20000 10000 0 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) 24
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. THANKS 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.