Ash 2013 conferenceApril 17th, 2013, Stockholm
B.Siret, D.Mole
Waste to Energy Plants
Ash cleaningwith TIL process
4 years of operation
Context
• Wet scrubbing systems produce:– Fly ash– Cake from the waste water treatment unit
• TIL is a ash treatment process– TIL process has been originally developed to make
the fly ash from WtE plant compliant with requirements, for « class II » landfill
Original installation in Fribourg (CH) in 1999
Context
• Operators expect a unique disposal for the fly ash and WWT cake in « class II » landfill
• LAB upgraded the TIL process to allow a safe and economical discharge of the blend+ Fly ash + Waste water cake
Installation in Sundsvall (SW) in 2008
TIL process
• TIL stands for Traitement Intégré LAB• TIL is a family of washing processes
– Different countries, different requirements, different TIL
• Fully integrated in wet systems– Well suited for hazardous and Waste to Energy gas
cleaning units
• Requires the wet scrubbers– Cannot be stand-alone
• Commercial, patented, and in-use process
TIL process
• Fly ash is collected, usually by an ESP– Economizer ashes may be also collected
• Water is added to make a slurry– To the collected ashes
– To the sludge from the waste water treatment
• Other additives may be used• Mixing is performed is a well stirred tank• Some acidic water is added
– Drains from the acidic scrubber
TIL Principle4 stages of treatment
Water effluent with low heavy metals content
Disposal of the safe cake. Heavy metals are contained under stabilised form.
TIL: Principles 4 stages of treatment
• First stage: is the mixing of the boiler and fly ashes with the waste water treatment sludge in the ash preparation tank.– Forced leaching ; toxicity reduction
• Second stage is the final stabilization / rinse on the band filter where the cake is being dried out.– Liquids are recycled to the acidic scrubber (G1 in Lab Wet system).
• Third is the separation of the heavy metals in the The heavy metals are precipitated.– Waste water cleanup– Sludge that contains the precipitate sent to stage 1.
• Fourth stage is the scrubber. The acidic waters needed for the TIL are created, when the flue gas cleaning process takes place.– Flue gas cleaning
TIL process schematics
1. ESP 2 Scrubbers5. Waste water treatment6. Filter 4 dewatering7. Ash slurry tankH Additives R stabilized
end product
TIL Equipments
TIL Equipments
TIL Equipments
End product
End product
Ecotox tests
European council defined 14 properties that would be used to decide whether a solid would be hazardous or not
•It involves tests – both on leachates and on the solids– There are acute and chronic toxicity tests
•For example– Aqueous leachate introduced to less than 1% in water
would inhibit more than 20% of ceriodaphnia reproduction– Less than 10% of the solid in a substrate would inhibit the
spouting or the growth of lettuce by more than 50%
Ecotox Protocols
• Leaching tests– EN 12457-2
• Percolation tests– EN 14405
• Ecotox tests (H14)– Toxicity tests based on the solids (ashes)
• ISO 11269-2 lettuce growth• ISO 11266-1 Eisenia Fetida worms
– Toxicity based on leachates• EN ISO 6341 Daphnia Magna• ISO 11348-3 Vibrio Fischeri MICROTOX• ISO 8692 Algae growth• NF T90-376 Ceriodaphnia
heavy metals leachate (S)
metal (see key)
mg/
kg (
dry)
polluant201-Mo 02-As 03-Se 04-Pb 05-Cd 06-Cr 07-Sb 08-Cu 09-Ni 10-Hg 11-Zn limit
0 2 4 6 8 10 120.001
0.01
0.1
1
10
100
Ecotox Results : leaching
All figures well below the limits
Heavy metals percolation (S)
metal (see key)
c0
mg/
l
polluant201-Mo 02-As 03-Se 04-Pb 05-Cd 06-Cr 07-Sb 08-Cu 09-Ni 10-Hg 11-Zn limit
0 2 4 6 8 10 120.001
0.01
0.1
1
10
100
Ecotox Results: Percolation
All figures are well within limits
Ecotox results
Ecotox Results
Raw ash Toxicit
y Treated mix Toxicity
MEDD 2000
Without TIL With TIL limit
Daphnia CE 50-24h 32.4 OK [ 28 – 68 ] OK
CE 50-48h 21.8 OK [20.6 – 29.7 ] OK 10
MICROTOX CE-50-35' >100 OK Non toxic @80% OK 10
Ceriodaphnia CE20-7d 0.19 TOXIC [2.2 – 4.5] OK 1
Algae CE20-72h 3.7 OK [ 7.4 -19.9] OK 1
Lettuce CE 50-7d 0.93 OK [15.9 - 100] OK
CE 50-14d 0.95 TOXIC [15.4 -100] OK 10
Worms CE50-14d 5.5 TOXIC [32.7 - 41.9] OK
Ecotox: results
TIL end Product is deemed
« not harmfull to the environment »
– No long term toxicity– No acute toxicity
In summary
TIL wet process is a well integrated process that offers– Stabilization of the mix of fly ash/waste water treatment
sludge
• Metals
• Soluble fraction reduction
– Reduction of the toxicity to the environment
• Allows discharge in much more economical conditions
It is readily available and proven to be industrialy successful
Thank you !
Contact:
Dominique [email protected]+33 (0)4 94 18 56 38+33 (0)6 89 95 77 71
Christophe [email protected]+33 (0)4 94 18 56 16+33 (0)6 82 14 60 00
