a model and tool to calculate life cycle inventories of chemicals discharged down … · 2018. 6....
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A model and tool to calculate life cycle inventories of chemicals
discharged down the drain
Ivan Muñoz, 2.-0 LCA consultants
Komalshree Muthukrishnan & Nikolaj Otte, Henkel AG & Co
Gert Van Hoof, Procter & Gamble
Giles Rigarlsford, Unilever
SETAC Europe 26th Annual Meeting, Nantes, 23 May 2016
Background and aim
§ The fate of household chemicals following use is generally to municipal wastewater treatment plants (WWTP) although in some countries this may be limited
§ Current WWTP models in LCA, e.g. Ecoinvent (Doka 2007): § Reflect average conditions in WWTPs, rather than the specific
fate of particular chemicals (e.g. Degradability)
§ Omit the impact of direct discharges
§ Our goal was to develop a model that calculates chemical-specific LCIs of chemicals discharged down the drain or to the environment
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Doka, G. (2007) Life Cycle Inventories of Waste Treatment Services. Final report ecoinvent 2000 No. 13, EMPA St. Gallen, Swiss Centre for Life Cycle Inventories, Duebendorf, Switzerland.
Concept, scope and data
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Chemical) Phys.&Chem.&proper-es&
Environmental&fate&model&(USES:LCA)&
WWTP&fate&factors&
WWTP&+&sludge&disposal&LCI&
model&&
&Model&for&environmental°rada-on&
LCI)of)chemical)down)the)drain)includes:)! Sewer&infrastr.&! WWTP&infrastr.&! Energy&input/
output&! Chemicals&! Emissions&! Sludge&transport&! Sludge&disposal&
WWTP effluent
WWTP process, sludge disposal, etc.
Direct discharge
Connection to WWTP
WW LCI
• Organic/inorganic • Composition (C, H, O, N, S, P, Cl) • Molecular weight • Vapour pressure • Solubility • Kow • Half-lives in the environment
(soil, water, air)
• Fraction degraded • Fraction volatilized • Fraction to sludge • Anaerobic degradability
• % population connected to WWTPs • WWTP includes N and P removal • Country • Sludge disposal scenario
§ Mass and energy balances
§ Functional unit is 1 kg of chemical
§ Multifunctionality solved by substitution (credits)
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Concept, scope and data
WWTP
Degradation in environment
Landfill
Incineration Volatilization Effluent
Sludge
Landfarming
Application to soil
Chemical
Own model
Models by Gabor Doka. Ecoinvent v2 report nº 13
Substituted:
- Electricity
- Fuels
- Fertilizer
Own model
Muñoz, I. et al. (2013) Accounting for greenhouse gas emissions from the degradation of chemicals in the environment . IJLCA, 18:252–262.
Inputs from technosphere WWTP operations
Chemical
Feffluent
Fair
Fdeg
Fsludge
Emissions to air
Biological treatment
Anaerobic digestion
- Electricity
- Heat - Sewer infra
- WWTP infra
Sludge to disposal
- Methanol (N removal)
- Iron chloride (P removal)
Co-generation
Emissions to water Fraction not removed
Fraction volatilized
Fraction to biodegradation
Fraction to sludge
Activated sludge
Biogas
WWTP model
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Anaerobic digestion:
Fsludge + C5H7ON2 + H2O → CH4 + CO2 + N2 +H2S + digested sludge
P removal:
FeCl3 + PO4 + OH - → FePO4 + Fe(OH)3 + Cl -
Aerobic degradation of carbonaceous organic matter:
CaHbOcNd + O2 → C5H7ON2 + CO2 + H2O + NH3
N removal: Nitrification
NH4+ + O2 + HCO3
- → C5H7ON2 + NO3- + H2O + H2CO3
Denitrification
NO3- + CH3OH + H+ → C5H7ON2 + N2 + CO2 + H2O
WW LCI: key features
§ All calculations in a single Excel file: WW LCI.xlsx
§ 30 chemicals can be assessed at a time, separately or as a mixture
§ Entirely parameterized, all values can be changed by the user
§ Resulting LCIs use ecoinvent 3 nomenclature
§ WW LCI does not include impact assessment calculations
§ LCIs can be exported as CSV files to LCA software: SimaPro
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WW LCI in Excel
7
Sheet ‘WWTP input’
Sheet ‘USES-LCA input’
WW LCI in Excel
8
Sheet ‘LCI output’
WW LCI in Excel
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Sheet ‘Ready to CSV output’
Excel
CSVmaker
WW LCI: import to SimaPro
10
Data sets in SimaPro
WW LCI: import to SimaPro
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Data set in SimaPro
WW LCI compared to Ecoinvent model
§ Same connection level to WWTP: 100%
§ Same sludge disposal: 58% incineration, 42% agriculture (DE)
§ Same sewer-WWTP size: 4.7E10 L/year
§ Same functional unit: 1 kg chemical in wastewater influent
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Name CAS number
Key features
Tetraacetylethylenediamine (TAED)
10543-57-4 Organic, degradable, contains N and fossil C
Ethanol 64-17-5 Organic, degradable, contains biogenic C
Diethylenetriamine penta(methylene phosphonic acid) (DTPMP)
15827-60-8
Organic, poorly degradable, contains N and P, contains fossil C
Sodium carbonate 497-19-8 Inorganic, soluble Zeolite A 1344-00-9 Inorganic, insoluble Sodium tripolyphosphate (STPP) 7758-29-4 Inorganic, soluble, contains P
WW LCI compared to Ecoinvent model GHG emissions, in kg CO2-eq/kg chemical (IPCC 2013)
(biogenic CO2 considered neutral)
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!1#
0#
1#
2#
3#
4#
5#
6#
Ecoinvent# WW#LCI#
DTPMP# !0.2%
!0.1%
0%
0.1%
0.2%
0.3%
0.4%
0.5%
0.6%
0.7%
Ecoinvent% WW%LCI%
Ethanol%
0"
0.01"
0.02"
0.03"
0.04"
0.05"
0.06"
0.07"
0.08"
Ecoinvent" WW"LCI"
Zeolite"A"
!1#
0#
1#
2#
3#
4#
5#
6#
7#
Ecoinvent#
Model#
WW#LCI#
Ecoinvent#
DTPMP#Che
mic
al#
Ethanol#Che
mic
al#
Sodium#
carbon
ate#
Che
mic
al#
STPP#Che
mic
al#
TAED#Che
mic
al#
Zeolite#
A#
Other#acGviGes#
P#ferGlizer#
N#ferGlizer#
Natural#gas#
Electricity#
WWTP+sewer#infra#
Methanol#
Iron#sulphate#
Aluminium#sulphate#
Iron#chloride#
Chemical#degradaGon#
0.0E+00%
5.0E'05%
1.0E'04%
1.5E'04%
2.0E'04%
2.5E'04%
Ecoinvent% WW%LCI%
Sodium%carbonate%
Note different Y axis scale
WW LCI compared to Ecoinvent model Freshwater ecotoxicity, in CTU-eq/kg chemical (USEtox)
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!1#
0#
1#
2#
3#
4#
5#
6#
7#
Ecoinvent#
Model#
WW#LCI#
Ecoinvent#
DTPMP#Che
mic
al#
Ethanol#Che
mic
al#
Sodium#
carbon
ate#
Che
mic
al#
STPP#Che
mic
al#
TAED#Che
mic
al#
Zeolite#
A#
Other#acGviGes#
P#ferGlizer#
N#ferGlizer#
Natural#gas#
Electricity#
WWTP+sewer#infra#
Methanol#
Iron#sulphate#
Aluminium#sulphate#
Iron#chloride#
Chemical#ecotoxicity#
!20$!10$0$
10$20$30$40$50$60$70$80$
Ecoinvent$ WW$LCI$
DTPMP$
!100$0$
100$200$300$400$500$600$700$800$900$
Ecoinvent$ WW$LCI$
Sodium$carbonate$!20$
0$
20$
40$
60$
80$
100$
120$
140$
Ecoinvent$ WW$LCI$
Zeolite$A$
!4#
!2#
0#
2#
4#
6#
8#
10#
Ecoinvent# WW#LCI#
Ethanol#Note different Y axis scale
Is it sensible for inorganics to have such high USEtox characterization factors?
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WW LCI: assessing direct discharges
0"
1"
2"
3"
4"
DTPMP" Ethanol" Sodium"carbonate"
STPP" TAED" Zeolite"A"
kg"CO2Aeq
/kg"chem
ical"
WW"LCI" Direct"discharge"
Population connected to WWTP: 100% vs. 0%
0.00#0.01#0.02#0.03#0.04#0.05#0.06#0.07#0.08#0.09#0.10#
DTPMP# Ethanol# Sodium#carbonate#
STPP# TAED# Zeolite#A#
kg#NFeq/kg#che
mical#
WW#LCI# Direct#discharge#
0.00#
0.05#
0.10#
0.15#
0.20#
0.25#
0.30#
DTPMP# Ethanol# Sodium#carbonate#
STPP# TAED# Zeolite#A#
kg#P@eq/kg#che
mical#
WW#LCI#@#100%#connecHon# Direct#discharge#
0"100"200"300"400"500"600"700"800"900"
DTPMP" Ethanol" Sodium"carbonate"
TAED" Zeolite"A"
CTUDeq/kg"che
mical"
WW"LCI"D"100%"connecMon" Direct"discharge"
GHG emissions Freshwater ecotoxicity
Marine eutrophication Freshwater eutrophication
0.00#0.05#0.10#0.15#0.20#0.25#0.30#
DTPMP# Ethanol# Sodium#carbonate#
STPP# TAED# Zeolite#A#
kg#P@eq/kg#che
mical#
WW#LCI#@#100%#connecHon# WW#LCI#@#Direct#discharge#(0%#connecHon)#
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§ WW LCI can handle a complete substance flow analysis for chemicals in wastewater
§ WW LCI addresses specific degradability, sorption to sludge, etc. This has substantial influence in the calculation of energy use, sludge production, N and P removal…
§ WW LCI accounts for direct discharges, relevant for developing countries
§ WW LCI closes the carbon balance when sludge is applied in agriculture
§ WW LCI accounts for displaced energy and fertilizers
§ WW LCI can represent scenarios other than Switzerland
Compared to Ecoinvent model…
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Conclusions & Outlook § Improvement in modelling the end of life for chemical substances
§ Still some limitations: § Data-demanding
§ Complete flow analysis only for C, N, P, S and Cl
§ Metals not yet supported
§ Import of data sets only available for SimaPro so far
§ Work in progress with Technical University of Denmark (DTU) on integration of WW LCI with Sewage LCI: § Adding treatment by septic tanks
§ Adding WWTPs with primary treatment only
§ Adding WWTPs with tertiary treatment (sand filter)
§ Sludge composting
§ Built-in country scenarios (% connection, sludge disposal)
More info: http://lca-net.com/projects/show/wastewater-lci-initiative/
Reference:
Muñoz I, Otte N, Van Hoof G, Rigarlsford G. A model and tool to calculate life cycle inventories of chemicals discharged down the drain. Submitted to the International Journal of Life Cycle Assessment.
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Thank you!