sustainable management of fly ashes from waste …...sustainable management of fly ashes from waste...

Sustainable Management of Fly Ashes from Waste Incineration

Florian HuberResearch Center of Waste and Resource ManagementCD Laboratory for Anthropogenic Resources

Symposium: Science to support Circular Economy19.09.2018, Vienna

Sustainable Management of Fly Ashes from Waste Incineration 2

Introduction

Status quo

• About 3% of the waste input in waste incineration plants arise as flyash, which constitutes a hazardous waste

• Mass of fly ash generated in Europe: 900,000 t/a

• Fly ash mass from grate furnaces in Vienna: 18,000 t/a

→Exceeds limits for Hg total content, Pb and TDS leachate content

Morf, L.S., Brunner, P.H., Spaun, S., 2000. Effect of operating conditions and input variations on the partitioning of metals in a municipal solid waste incinerator. Waste Management and Research 18, 4–15.


Introduction

• Stabilisation with cement• Underground deposits• Extraction procedures• Thermal treatment• Neutralisation with waste acid• Utilisation in cement production

Assess the performance of management options with regard to thegoals of waste management

MSWI fly ash management options

Aim of the study


Environmental assessment



Scenarios

• Establishment of different MSWI fly ash management scenariosScenario 1 Underground depositScenario 2a Stabilisation with 1 Mg cement/Mg fly ashScenario 2b Stabilisation with 0.3 Mg cement/Mg fly ashScenario 3a Metal recoveryScenario 3b Metal and salt recoveryScenario 4a Thermal treatment in coal-fired furnaceScenario 4b Thermal treatment in natural gas-fired furnaceScenario 5a Thermal co-treatment with combustible waste in a rotary kiln incineratorScenario 5b Thermal co-treatment with combustible waste in a grate furnace incineratorScenario 6a Utilisation of fly ash in cement productionScenario 6b Utilisation of fly ash in cement production with salt recovery



Methodology

• Life Cycle Assessment to estimate environmental impact• Functional unit: treatment and disposal of 1 t of MSWI fly ash• Material flow analysis conducted to determine input and output flows• Average transfer coefficients for heavy metals from fly ash to

products and residues calculated from experimental and literature data

• Life cycle inventory data from the ecoinvent database for all processes

• Life cycle impact assessment according to ReCiPe method• System expansion to account for co-products



Uncertainty analysis

• Determination of the uncertainty of every parameter (literature data, experiments, expert judgement)

• Propagation of uncertainty by Monte Carlo simulation (100.000 runs)



Consideration of long-term emissions

• Heavy metals can leave above ground landfills via the leachate• Assumptions:

Year 0 – 100: leachate collection and treatment Year >100: no leachate collection



Results

-0,001

0

0,001

0,002

0,003

0,004

1 2a 2b 3a 3b 4a 4b 5a 5b 6a 6bHum

an h

ealth

[DAL

Y]

-0,000005

0

0,000005

0,00001

0,000015

1 2a 2b 3a 3b 4a 4b 5a 5b 6a 6b

Ecos

yste

m q

ualit

y [s

peci

es y

ears

]

0

20

40

60

80

100

1 2a 2b 3a 3b 4a 4b 5a 5b 6a 6b

Reso

urce

s [U

SD]

-50

0

50

100

150

1 2a 2b 3a 3b 4a 4b 5a 5b 6a 6b

Tota

l sco

re [-

]• Metal recovery has the lowest environmental impact in all endpoint

categories• Utilisation of fly ash in cement production has low impact in same

impact categories but high impact in others• Salt recovery increases environmental impact


Economic assessment


Economic assessment

Scenarios

• Same scenarios and system boundaries like environmental assessment

Scenario 1 Underground depositScenario 2a Stabilisation with 1 Mg cement/Mg fly ashScenario 2b Stabilisation with 0.3 Mg cement/Mg fly ashScenario 3a Metal recoveryScenario 3b Metal and salt recoveryScenario 4a Thermal treatment in coal-fired furnaceScenario 4b Thermal treatment in natural gas-fired furnaceScenario 5a Thermal co-treatment with combustible waste in a rotary kiln incineratorScenario 5b Thermal co-treatment with combustible waste in a grate furnace incineratorScenario 6a Utilisation of fly ash in cement productionScenario 6b Utilisation of fly ash in cement production with salt recovery


Economic assessment

Methodology

• Functional unit and uncertainty analysis identical to environmental assessment

• Discounted cash flow analysis

c0 investment cost [EUR]c1-cT discounted cash flow for year 1 to T [EUR]T time [a]r discount rate [-]


Economic assessment

Results

0

200

400

600

800

1000

1200

1400

1 2a 2b 3a 3b 4a 4b 5a 5b 6a 6b

Cost

for t

reat

men

t and

dis

posa

l [EU

R]


Conclusions


Conclusions

• In-depth environmental and economic assessment of 13 different MSWI fly ash management scenarios conducted

• Recovery of metals, minerals for cement production and soluble chloride salts from MSWI fly ash possible

• Very low environmental impact of metal recovery, but impact of utilisation in cement production higher compared to disposal scenarios

• Economic costs for metals and minerals recovery higher compared to disposal scenarios

• Recovery of soluble chloride salts increases environmental impact and economic costs


Conclusions

• Results of environmental and economic assessment not necessarily in line with waste hierarchy

• Trade-offs required to solve conflict of objectives

• Hazardous substances require final sinks

• No utilisation at any cost

• Decisions about utilisation or disposal should be made on a case by case basis after well-founded analysis


ContactFlorian Huber Project Assistent

Phone: +43 1 58801 [email protected]

Questions and Discussion

sustainable management of fly ashes from waste …...sustainable management of fly ashes from waste...

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