ash 2013 conference april 17th, 2013, stockholm b.siret, d.mole waste to energy plants ash cleaning...
TRANSCRIPT
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
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
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