LCA and LCC of the ozonation system in Neugut

Consortium Meeting on June 17 2015, Dübendorf

This project has received funding from the European Union’s Seventh Programme for Research, Technological Development and Demonstration under Grant Agreement no. 308339.

WA5 Anna Kounina, PhD.

Quantis Kristina Wencki,

IWW 17-06-2015

Introduction and key figures • The waste water treatment plant (WWTP) Neugut was built in 1964 as one of the first municipal

WWTPs in Switzerland • Since 2014, it is the first full scale ozonation in a Swiss WWTP to eliminate organic micropollutants

2

Neugut case study presentation

Parameter Unit Value Waste water capacity p.e. 150’000 Current operational p.e. 105’000

Daily waste water treatment m3/day 20’000 to 50’000

Hydraulic capacity (dry weather peak flow) m3/day 30’000 Hydraulic capacity (wet weather peak flow) m3/day 57’000 Annual volume treated m3/year 8’600’000 Biological efficiency % 96 to 99 Nitrogen removal % 73 Phosphorus removal % 95 Ozonation system hydraulic max capacity for dry weather m3/day 30’000 Ozonation system hydraulic max capacity for wet weather m3/day 57’000

Ozonation – studied system

Ozonation system • Ozone is generated by electrolysis from oxygen stored in liquid oxygen tanks at the waste

water treatment plant • The effluent of the secondary clarifier of the WWTP is mixed with the ozone gas in the

ozone reactor by ceramic diffusors to dissolve it into the water • Micropollutants react with the dissolved ozone, reducing or eliminating their adverse effects

on the environment and humans by degrading large organic micropollutants into smaller non-toxic molecules

• The sand filter removes the remaining by-products by biodegradation and filtration

Method

LCA characteristics

• LCA considers both direct (e.g., emissions from wastewater treatment plant) and indirect impacts (e.g., infrastructure of the wastewater treatment plant, electricity production)

• The model used to evaluate (eco)toxic impacts USEtox is generic: it considers potential impacts in a generic water body, not monitored impacts in the Glatt river

LCC characteristics

• Within LCC the initial investment costs of the wastewater treatment plant and the operational expenditure (e.g. personnal, electricity, maintenance) are considered over the whole life cycle of the system (excl. removal phase)

• Assumed lifetime of the system: 30 years

• Discounting rate: 3%

What are the environmental benefit and impact of the ozonation system in Neugut in terms of ecotoxicity?

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Freshwater ecotoxicity indicator

Freshwater ecotoxic impact of the wastewater treatment plant emissions when considering only 11 monitored organic micropollutants (no heavy metals)

How do the monitored micropollutants score in terms of ecotoxicity?

• Among the monitored substances, diclofenac contributes most to ecotoxicity, followed by sulfamethoxazole and benzotriazole

• Over the ozonation stage, micropollutants are removed from 43 to >99% (EAWAG data)

How do the monitored micropollutants score compared to other existing substances?

• Monitored substances cover a wide range of toxicity • The most toxic substance (per kg emitted) on aquatic ecotoxicity is sulfamethoxazole

5th centile: 7.1 CTUe

95th centile: 6.2E+5 CTU

Freshwater ecotoxicity indicator

High toxicity CF 95th centile: 6.2E+5 CTUe/kgemitted

Average toxicity CF median: 1.36E+3 CTUe/kgemitted

Extrapolation to the entire load of micropollutants... Low toxicity

CF 5th centile: 7.1 CTUe/kgemitted

• Substance removal: We assume 87% of substances are removed over the ozonation stage (average over 10 monitored substances in Neugut)

• Total micropollutant load: We estimated total micropollutant load as an average of the load reported in Schwentner (2011), Margot et al. (2013) and Goetz et al. (2010): 96.5 μg/L

• When extrapolating the toxic impact to the entire micropollutant load, the micropollutant emissions represent a significant contribution to freshwater ecotoxicity impact in case the toxicity of the micropollutant load is average to high

What are the environmental benefit and impact of the ozonation system in Neugut in terms of climate change?

10

Climate change

Climate change results: • The liquid oxygen and electricity production add 6% more impact on climate change

compared to the Neugut main wastewater treatment plant

N2O emissions

What is the life cycle cost of the ozonation system?

12

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OPEX and CAPEX

Investment • Initial investment costs for the Neugut

wastewater treatment plant are lowered by the fact that sandfilters were already in place and no pumping is required.

• The ozonation stage causes 2,4 % additional investment costs.

Operational Costs • Operational costs of the Neugut

plant are dominated by personnal, electricity and capital interest.

• Operating the ozonation stage increases operational costs up to 7,3 %.

23.06.2015 14

Total life cycle costs

Life Cycle Costs (30a, 3% discount, no inflation)

Business as usual: Ø 5.12 Mio. €/a

w/ozonation: Ø 5.29 Mio. €/a

Key learnings

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Key learnings

Ecotoxicity results

• When considering only 10 monitored micropollutants, the environmental benefit of ozonation is hardly visible for the aquatic ecotoxicity

• Among monitored micropollutants, the main contributors are diclofenac, followed by benzotriazole,and sulfamethoxazole emissions

• These monitored micropollutants cover a wide range of toxicity

• When extrapolating the toxic impact to the entire micropollutant load, the micropollutant emissions represent a significant contribution to freshwater ecotoxicity impact in case the toxicity of the micropollutant load is average to high, i.e. between the median and the 95th centile of organic substances CFs in USEtox

Climate change

• The liquid oxygen and electricity production add 6% more impact on climate change compared to the Neugut main wastewater treatment plant

Life cycle cost

• Adding an ozonation stage causes additional 2,4 % of the plant‘s initial investment costs

• Operational costs of the ozonation stage are dominated by costs of electricity and oxygen, increasing the initial operational costs by about 0.01 €/m³treated

Thank you for you attention!

Annex

Introduction

Introduction and key figures • The waste water treatment plant (WWTP) Neugut was built in 1964 as one of the first municipal

WWTPs in Switzerland • Since 2014, it is the first full scale ozonation in a Swiss WWTP to eliminate organic micropollutants

21

Neugut case study presentation

Parameter Unit Value Waste water capacity p.e. 150’000 Current operational p.e. 105’000

Daily waste water treatment m3/day 20’000 to 50’000

Hydraulic capacity (dry weather peak flow) m3/day 30’000 Hydraulic capacity (wet weather peak flow) m3/day 57’000 Annual volume treated m3/year 8’600’000 Biological efficiency % 96 to 99 Nitrogen removal % 73 Phosphorus removal % 95 Ozonation system hydraulic max capacity for dry weather m3/day 30’000 Ozonation system hydraulic max capacity for wet weather m3/day 57’000

Ozonation – studied system

Ozonation system • Ozone is generated by electrolysis from oxygen stored in liquid oxygen tanks at the waste

water treatment plant • The effluent of the secondary clarifier of the WWTP is mixed with the ozone gas in the

ozone reactor by ceramic diffusors to dissolve it into the water • Micropollutants react with the dissolved ozone, reducing or eliminating their adverse effects

on the environment and humans by degrading large organic micropollutants into smaller non-toxic molecules

• The sand filter removes the remaining by-products by biodegradation and filtration

LCA study

Objective and main concepts • This Life Cycle Assessment (LCA) study quantifies potential environmental impacts and

benefits of the Neugut wastewater treatment plant • Environmental impact indicators show:

• Environmental impacts generated for example by infrastructure, operation, emissions into air and water

• Environmental benefits through energy recovery Scenarios • The baseline scenario relies on the wastewater treatment plant without ozonation • The ozonation scenario considers ozonation system infrastructure as well as operation

(the production of liquid oxygen, electricity and removal of micropollutants)

Functional unit • The functional unit is: 1 m³ of municipal wastewater released (including wet and dry

weather conditions) Impact indicators • Selected indicators are based on the ILCD recommendations and cover the following

impact categories: climate change, human toxicity cancer effect, human toxicity non-cancer effect, freshwater ecotoxicity, particulate matter, terrestrial acidification, freshwater eutrophication, marine eutrophication

LCA study

Assumptions Plant operation • Main plant infrastructure: modelled with the ecoinvent process Wastewater treatment plant,

class 2/CH/I U brought to 1 m3

• Annual volume treated is 14'400'000 m3/year • Estimated lifetime: 30 years

• 100% of the sludge is dried and burned in a cement plant, as a substitute for coal • 0.11 kg dry weight / m3 treated • LHV for sludge with 50% water is assumed 4 MJ / kg

(http://www.waterleau.com/files/Integrated_sludge_treatment.pdf) • From July 2015, the sludge will be dried in another wastewater treatment plant and incinerated (scenario not

included in this study) • Sludge incineration inventory is modelled with the tool for waste disposal in Municipal Solid Waste Incinerators

MSWI for ecoinvent v2.1 (2008) • Flocculant by-products are not considered in water emissions • Electricity and heat recovery from biogas burning are used internally at the wastewater

treatment plant Emissions into air • N2O emissions: 0.5% of denitrified N (expert judgement from Christian: 70% of total N is

present as NH4) is transformed into N2O (expert estimation from Neugut plant operators) • NH3 emissions: 0.6 % of influent NH4 (expert judgement from Christian: 70% of total N is

present as NH4) is transformed into gaseous NH3 (adopted from Bardtke et al., 1994). Emissions into water • Ozonation by-products: We assume that micropollutants are degraded with ozonation and

that there are no toxic by-products in the wastewater treatment plant effluent

Wastewater treatment performance

Wastewater treatment performance • The Neugut wastewater treatment main plant aims at reducing the total eutrophying load • The results show that the wastewater treatment reduces the wastwater impact on freshwater and

marine eutrophication (P emissions reduced by 95% and N emissions reduced by 73%, information from Neugut operators)

Global results

Global results

CC Climate Change, HTCE Human Toxicity Cancer Effect, HTNCE Human Toxicity non-Cancer Effect, PM Particulate matter, TA Terrestrial Acidification, FE Freshwater eutrophication, ME Marine eutrophication, FE Freshwater ecotoxicity, B Baseline, O Baseline with Ozonation, O in DE Sensitivity analysis with German grid mix

Global results, comparison between baseline scenario and ozonation: • The main plant infrastructure contributes to a significant part of the impact for all impact

categories (5 to 64%), followed by electricity consumption for the main plant operation (2 to 24%) • There are benefits from sludge burning • The impact of the ozonation (mainly liquid oxygen and electricity production) adds from 0 to 7% of

the impact among all categories compared to the baseline scenario

Global results sensitivity analysis

CC Climate Change, HTCE Human Toxicity Cancer Effect, HTNCE Human Toxicity non-Cancer Effect, PM Particulate matter, TA Terrestrial Acidification, FE Freshwater eutrophication, ME Marine eutrophication, FE Freshwater ecotoxicity, B Baseline, O Baseline with Ozonation, O in DE Sensitivity analysis with German grid mix

Global results sensitivity analysis: • We modelled the ozonation scenario in Germany (with German electricity grid mix) to test the

influence of the electricity grid mix on the results • The impact of the Neugut plant with the ozonation system with the German grid mix provides

results from 5% to 80% larger than with the Swiss grid mix

Climate change results

Climate change

Climate change results: • The liquid oxygen and electricity production add 6% more impact on climate change compared

to the baseline scenario • The electricity production in Switerland have a low impact on climate change given that

Switzerland has less than 10% of its energy based on fossil fuels or coal

N2O emissions

Climate change sensitivity analysis

Climate change results, sensitivity analysis: • We modelled the ozonation scenario in Germany (with German electricity grid mix) to test the

influence of the grid mix on the results • The impact of the Neugut plant with the ozonation system with the German grid mix provides

results 80% larger than with the Swiss grid mix

Wastewater treatment plant contribution

Contribution analysis of the wastewater treatment plant process to climate change: • We explore the origin of the contribution of the wastewater plant infractructure impact on

climate change • Concrete and reinforcing steel contribute to 72% of the impact for the ecoinvent process for

wastewater treatment infrastructure

(Eco)toxicity results

(Eco)toxicity

Human toxicity and freshwater ecotoxicity, sensitivity analysis • The ozonation system reduces

9% of the impact on the human toxicity non-cancer effect category

• Next slides show the extrapolation of the (eco)toxicity score to a wider set of substances than the 10 reference substances

(Eco)toxicity

Next slide shows the zoom on the yellow part

Contribution analysis

Contribution analysis: • Human toxicity, cancer effect is

dominated by primidone emissions

• Human toxicity, non-cancer effect is dominated by diclofenac emissions

• Freshwater ecotoxicity is dominated by diclofenac, followed by benzotriazole,and sulfamethoxazole emissions

Substance toxicity analysis

Toxicity analysis: • We analyse the toxicity of the

substances monitored at the Neugut wastewater treatment plant (per kg substance emitted) compared with organic substances covered in the USEtox database

• Monitored substances cover a wide range of toxicity

• The most toxic substace on human health, non cancer effect is diclofenac

• The most toxic substance on aquatic ecotoxicity is sulfamethoxazole

(Eco)toxicity extrapolation

Extrapolation • Given that the previous results are representative of only 10 monitored substances, we

extrapolated the (eco)toxicity score to the entire micropollutant load present in municipal wastewater

• Micropollutant load: We estimated total micropollutant load as an average of the load reported in Schwentner (2011), Margot et al. (2013) and Goetz et al. (2010)

• Toxicity uncertainty: Given the lack of knowledge on the average toxicity of the entire micropollutant load, we generated a toxicity characterization factor for 3 scenarios: 5th percentile, median and 95th percentile of the toxicity of the 3074 organic substances covered in USEtox

• Substance removal: We assume 87% of substances are removed over the ozonation stage (average over 10 monitored substances in Neugut) Description Value Unit Source

Sum micropollutants detected in WWTP influent to micropollutant removal stage at Sindelfingen 1.16E-04 kg.m−3 Schwentner (2011)

Sum micropollutants detected in WWTP influent to micropollutant removal stage by Margot et al. 8.18E-05 kg.m−3 Margot et al. (2013)

Sum micropollutants detected in WWTP influent to micropollutant removal stage by Goetz et al. 9.05E-05 kg.m−3 Goetz et al. (2010)

Average sum of micropollutants detected in WWTP effluent 9.62E-05 kg.m−3

Human health, cancer effect extrapolation

CF 5th centile: 2.3E-8 CTUh/kgemitted

CF 95th centile: 1.3E-3 CTUh/kgemitted

Human health, cancer effect extrapolation: • The micropollutant emissions represent a significant

contribution to the impact on human health, cancer effect in case the toxicity of the micropollutant load is high, i.e. towards to 95th centile of organic substances in USEtox

• For the CF at the 95th centile of organic substances in USEtox, the ozonation reduces the micropollutant emissions contribution from 69% to 22% of the total impact for the scenario

CF median: 3.0E-6 CTUh/kgemitted

CF 5th centile: 1.6E-8 CTUh/kgemitted

CF 95th centile: 1.2E-3 CTUh/kgemitted

Human health, non-cancer effect extrapolation

CF median: 4.3E-6 CTUh/kgemitted

Human health, non-cancer effect extrapolation: • The micropollutant emissions represent a significant

contribution to the impact on human health, non-cancer effect from an average to high toxicity, i.e. from the median to 95th centile of organic substances in USEtox

• Based on our initial assumption, the ozonation reduces the impact of micropollutants 87%.

Freshwater ecotoxicity extrapolation

CF 5th centile: 7.1 CTUe/kgemitted

CF 95th centile: 6.2E+5 CTUe/kgemitted

Freshwater ecotoxicity extrapolation • The results trend is the same as for the human

health, non-cancer impact

CF median: 1.36E+3 CTUe/kgemitted

Conclusion

Conclusion

Global results

• The main plant infrastructure contributes to a significant part of the impact for all impact categories (5 to 64%), followed by electricity consumption for the main plant operation (2 to 24%)

• There are benefits from sludge burning

• The electricity requirements have a low impact on energy related impact categories such as climate change and freshwater eutrophication (compared for example to Germany) given that Switzerland has less than 10% of its energy based on fossil fuels or coal

• The impact of the ozonation (mainly liquid oxygen and electricity production) adds from 0 to 7% of the impact among all categories compared to the baseline scenario

Conclusion

(Eco)toxicity results

• When considering only 10 monitored substances, the environmental benefit of ozonation is mainly visible for the human toxicity non-cancer effect (reduces 9% of the impact)

• The main contributors are primidone emissions for human toxicity, cancer effect, diclofenac emissions for human toxicity, non-cancer effect and diclofenac, followed by benzotriazole,and sulfamethoxazole emissions for freshwater ecotoxicity

• These monitored substances cover a wide range of toxicity

• When extrapolating the toxic impact to the entire micropollutant load, the micropollutant emissions represent a significant contribution to the human health and freshwater ecotoxicity impact in case the toxicity of the micropollutant load is average to high, i.e. between the median and the 95th centile of organic substances CFs in USEtox

Conclusion

Key limitation

• Human toxicity and ecotoxicity impact results correspond to potential impacts are not site-specific, given that the USEtox model is generic (does not consider local hydrology and species sensitivity)

• Ozonation by-products are not considered in this model

Conclusion

Updates from Nathalie Hubaux

• Gas and electricity used only internally

• Electricity used internally has been deduced from total electricity to be representative only of electricitiy from grid

• Additional flocculant input added: flonex CP_DW318, 42'000 kg /y (modeled as chemical organic)

• Correction of amount of emissions of nutrients (BOD, COD, P and N)

• 0.5% (instead of 0.6%) of denitrified N (expert judgement from Christian: 70% of total N is present as NH4) is transformed into N2O (expert estimation from Neugut plant operators)

• Udpates on sludge inventory with the tool for waste disposal in Municipal Solid Waste Incinerators MSWI for ecoinvent v2.1 (2008)

Thank you

Freshwater eutrophication

Freshwater eutrophication results: • The impact of the Neugut plant with the ozonation system with the German grid mix

provides overall results 87% larger than with the Swiss grid mix • The freshwater eutrophication impact comes from lignite mining disposal in landfill for

electricity production from coal

P emissions

Particulate matter

NH3

Terrestrial acidification

NH3

Marine eutrophication

N emissions