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 Moledmole@lab.fr+33 (0)4 94 18 56 38+33 (0)6 89 95 77 71

Christophe Pauletcpaulet@lab.fr+33 (0)4 94 18 56 16+33 (0)6 82 14 60 00