Pacification of Fly Ash by the Geochemical Active Clay Sediments - - PowerPoint PPT Presentation

Pacification of Fly Ash by the Geochemical Active Clay Sediments Process

Design of Environmental Plants Lab, School of Environmental Engineering, Technical University of Crete, Greece Zeologic S.A., Greece

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Petros Gikas1 & Socrates Argyropoulos2

Topics

School of Environmental Engineering Technical University of Crete

• Fly Ash sources
• Fly Ash characteristics
• Utilization/treatment practices
• Geopolymers
• The Geochamical Active Clay Sediments (GACS) process
• Experimental findings

Fly Ash source

School of Environmental Engineering Technical University of Crete

Fly Ash: Size and composition

School of Environmental Engineering Technical University of Crete

CaO Fe2O3 Al2O3 SiO2 Cu Zn Mo Cd Cr Ni Pb As Ba Sb Se

0.5-100μm

MgO K2O

Source: Current Sc. (2011), Vol.100

Fly Ash facts

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Source: http://www.tifac.org.in

Fly Ash: Uses

School of Environmental Engineering Technical University of Crete

Road construction Soil amelioration

Directive: 2003/33/EC

Cement Geopolymers Ceramics Metal recovery

Directive 2003/33/EC

School of Environmental Engineering Technical University of Crete

Enforces strict limits for leaching/percolation tests Especially cares for the stabilization of heavy metals

Geopolymers

School of Environmental Engineering Technical University of Crete

A relatively complex reaction (polycondensation) between aluminosilicate- containing powders (e.g. fly ashes and/or reactive clays) with alkali metal silicates or hydroxides

Geopolymers (active clay sediments):

Three-dimensionally cross-linking alumininosilicates amorphous inorganic materials Consist of various inorganic repeating units, such as: silico-oxide (-Si-O-Si-O-) silico-aluminate (-Si-O-Al-O-) ferro-silico-aluminate (-Fe-O-Si-O-Al-O-) alumino-phosphate (-Al-O-P-O-)

Geopolymerisation:

Portland cement Geopolymer

School of Environmental Engineering Technical University of Crete

• Irreversible adsorption of a large spectra of wastes (organic, inorganic,

heavy metals)

• Can be structured so to be adsorption-selective (eg: for heavy metals,
• rganic wastes, radioactive wastes, etc)

Use of geopolymers for wastewater, sludge and ash treatment:

• Binding materials
• Ceramics
• Arts and decoration
• Restoration of archeological findings
• Fire resistance materials
• Adsorption/encapsulation of wastes

Uses of geopolymers

Uses of geopolymers:

Geopolymer

School of Environmental Engineering Technical University of Crete

Fly Ash treatment by the GACS process

School of Environmental Engineering Technical University of Crete

• Introduction of Fly Ash
• Adjustment of moisture
• pH adjustment
• Chemical oxidation (if required)
• Adsorption on geopolymers (georeaction-1st phase)
• Aggregation by nanopolymers
• Georeaction-2nd phase
• Drying

Stabilized fly ash Reactor Reactor Reactor Geopolymer type II Reactor H2O Geopolymer type I Acid agent Oxidation agent Nano- polymer Hot air Reactor Reactor Fly ash

Raw and treated Fly Ash composition

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Before treatment After treatment

Visual observation of raw and treated Fly Ash

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Before treatment After treatment

Leaching tests according to 2003/33/EC, at L/S=2L/kg

School of Environmental Engineering Technical University of Crete

Compound L/S = 2 L/kg Limit (mg/kg) Measured (mg/kg)

Al

• 0.64

As 0.10 0.06 Ba 7.00 0.00 Cd 0.03 0.00 Cr (total) 0.20 0.11 Cu 0.90 0.10 Fe

• 0.46

Hg 0.003 0.00 Mo 0.30 0.08 Ni 0.20 0.19 Pb 0.20 0.00 Sb 0.02 0.00 Se 0.06 0.00 Zn 2.00 < 0.02 Cl- 550 0.00 F 4.00 0.36 Phenol Index 0.50 0.00 TDS 2.500 1.900 SO4

2-

560 480 DOC 240 0.00

Leaching tests according to 2003/33/EC, at L/S=10L/kg

School of Environmental Engineering Technical University of Crete

Compound L/S = 10 L/kg Limit (mg/kg) Measured (mg/kg)

Al

• 0.80

As 0.50 0.16 Ba 20.00 0.00 Cd 0.04 0.00 Cr (total) 0.50 0.27 Cu 2.00 0.10 Fe

• 0.37

Hg 0.01 0.00 Mo 0.50 0.09 Ni 0.40 0.33 Pb 0.50 0.00 Sb 0.06 0.00 Se 0.10 0.00 Zn 4.00 < 0.02 Cl- 800 0.00 F 10.00 0.14 Phenol Index 1.00 0.00 TDS 4.000 3.400 SO4

2-

1.000 980 DOC 500 0.00

Percolation tests according to 2003/33/EC

School of Environmental Engineering Technical University of Crete

Compound C0 (percolation test) Limit (mg/L) Measured (mg/L)

Al

• 0.74

As 0.06 0.032 Ba 4.00 0.00 Cd 0.02 0.00 Cr (total) 0.10 0.093 Cu 0.60 0.11 Fe

• 0.19

Hg 0.002 0.00 Mo 0.20 0.16 Ni 0.12 0.075 Pb 0.15 0.00 Sb 0.10 0.00 Se 0.04 0.00 Zn 1.20 < 0.02 Cl- 460 0.00 F 2.50 0.42 Phenol Index 0.30 0.00 TDS

• 2.800

SO4

2-

1.500 1.105 DOC 160 0.00

General view of wastewater treatment plant utilizing the GACS process

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School of Environmental Engineering Technical University of Crete

Geopolymer addition tank

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School of Environmental Engineering Technical University of Crete

Geopolymer inside the feeding silo

School of Environmental Engineering Technical University of Crete

School of Environmental Engineering Technical University of Crete

Filter press and sedimentation tank

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Conclusions

• The use of the Geochemical Active Clay

Sediments (GACS) process can pacify the Fly Ash

• Leaching and percolation tests indicated that

the treated sludge complies with all the requirements of the Directive 2003/33/EC

• The

process is ready to be applied in industrial scale

School of Environmental Engineering Technical University of Crete

Thank you for your attention

Correspondence: petros.gikas@enveng.tuc.gr