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&degrada-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

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Sheet ‘WWTP input’

Sheet ‘USES-LCA input’

WW LCI in Excel

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Sheet ‘LCI output’

WW LCI in Excel

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Sheet ‘Ready to CSV output’

Excel

CSVmaker

WW LCI: import to SimaPro

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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!