Life Cycle Assessment of Small and Decentralized ...

Life Cycle Assessment of Small and Decentralized Wastewater

Treatment PlantsMaria P. Papadopoulou

Assοciate Professor, School of Rural and Surveying Engineering, National Technical University of Athens

C.S.LaspidouAssοciate Professor, Department of Civil Engineer, University of Thessaly

A.LekaPh.D Survey Engineer, Teaching Staff, National Technical University of Athens

13th IWA Specialized Conference on Small Water and Wastewater Systems

Athens, 14th-17th September 2016

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Motivation

• The absence in the current Greek legislation of an

appropriate method for the estimation, assessment and

evaluation of environmental impacts of

an infrastructure plan and/or an activity

Aim

• The use of LCA is a reliable approach to evaluate and assess the environmental impacts assessment of WWTPs.

• The incorporation of LCA in the environmental permitting process.

NTUA, IWA 16th of September, Athens 2

Map 1: WWTPs Location (google earth)


WWTP PopulationFlow Rate

(m3/day)Treatment Technology

Koilada 800 160System of sub-surface, vertical and

horizontal flow constructed wetlands Rachoula 600 132 Biological Textile Filters

Mandra 1070 214 Rotating Biological Contactor (RBC)

Table1: Basic Characteristics of the WWTPs

NTUA, IWA 16th of September, Athens

• System of sub-surface, vertical and horizontal flow constructed wetlands (simple

and effective solution for the secondary treatment of waste, low maintenance systems,

little operation power)

• Biological Textile Filters (use synthetic textile filters with higher surface area than

conventional sand, naturally aerated, little power for aeration when compared to other

processes, production of little to no sludge)

• Rotating Biological Contactor (RBC) (combines advantages of traditional systems of

activated sludge -small area requirement- and biofilters -operational simplicity, low

operating costs)

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Population Equivalent = 600

Flowrate (m3/d) = 132

BOD5 (mg/lt) = 300

SS (mg/lt) = 350

TN (mg/lt) = 45.5

TP (mg/lt) = 13.6

WWTP in Rachoula WWTP in Mandras



BOD5 (mg/lt) = 330

SS (mg/lt) = 385

TN (mg/lt) = 50

TP (mg/lt) = 15

WWTP in Koilada



BOD5 (mg/lt) = 330

SS (mg/lt) = 385

TN (mg/lt) = 50

TP (mg/lt) = 15

WWTP’s Technical Characteristics

NTUA, IWA 16th of September, Athens5

Application of LCA methodology

Software SIMA PRO

Impact Assessment

Methodology

IMPACT 2002+

ReCiPe


International Organization for Standardization : ISO 14040:2006 & ISO 14044:2006.

LCA Stages


Sima Pro Software

Goal and Scope DefinitionInventory Analysis

(Processes)

Impact Assessment

(Characterization, Weighting, Normalization, Single Score)

Interpretation


Fig1: IMPACT 2002+ General Concept: Overall scheme of the IMPACT 2002+ vQ2.2 framework, linking LCI results via the midpoint categories to damage categories, based on Jolliet et al. (2003a).

IMPACT 2002+ Assessment Method


Figure 2: Representation of the relations between the inventory and the midpoint categories (environmental mechanisms) and the endpoint categories, including the single score (damage model).

ReCiPe Assessment Method


LCA Stage I: Goal and scope definition

Figure 3: System Boundaries,source: M.Papadopoulou et al, Thessaloniki 2015


Assumptions

• The life cycle of the plants was presumed to be equal to 40 years.

• LCA considers environmental impacts only during the operation phase for each WWTP under study.

• Qualitative features of influent and effluent flows in WWTPs have been obtained from the National Database of the Special Secretariat for Water and Wastewater Treatment normalized for our cases

• The LCA did not include the stages of grouping and weighting

• The quantities of brown coal and natural gas consumed for the production of the necessary energy were estimated based on their Energy mix 2016 Net Calorific Value (NCV).


LCA Stage II: Life cycle inventory analysisFlow diagram of the system


Figure 4: Flow Diagram of the systemsource: M.Papadopoulou et al, Thessaloniki 2015

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Methodological approach

Calculation of annual electrical power

consumption in the WWTPs Based on equipment designer specifications

Calculation of the quantities of the pollutants

emitted by the combustion of brown coal and

natural gas (CO2, NOx, SO2, PM)

Mixture of country’s fuel for the year 2016

Calculation of the CH4 emissions caused by

wastewater treatment

Calculation of the N2O emissions in the air

that originate from the discharge of processed

waste water in the aquatic recipient

Calculation of the N2O emissions in the air

that are caused by wastewater treatment

Qualitative features of influent and effluent

flows in WWTPs

National Database of the Special Secretariat for

Water and Wastewater Treatment Plants


LCA Stage III: Life cycle impact assessment: Characterization: Percentage contribution of characterized results of WWTPs system processes per category of environmental impact for 1m3 of incoming wastewater (ReCiPe)


WWTP Koilada-Artificial Wetland WWTP Rachoula-Biological Textile Filters

WWTP Mandra-RBC

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Percentage contribution of characterized results of WWTP Rachoula per category of environmental impact for 1m3 of incoming wastewater


IMPACT

2002+

Re

Ci

Pe

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Comparison among the normalized results of the three WWTPs per category of environmental impact for 1m3 of incoming wastewater (ReCiPe)

WWTP Coal Energy Gas Energy Waste Water Treatment Total (mPt)

Koilada - - 36.5 36.5

Rachoula 0.894 0.424 10.3 11.6

Mandra 24.1 0.827 2.27 27.2


WWTP Treatment Technology

KoiladaSystem of sub-surface, vertical and horizontal flow

constructed wetlands

Rachoula Biological Textile Filters

Mandra Rotating Biological Contactor (RBC)

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All modern techniques used at the WWTPs reduce the environmental impacts

caused by greenhouse gases (CH4, Ν2Ο, CO2) in wastewater treatment plants.

Land occupation should not be ignored or underestimated during the design of

a WWTP especially in the case of artificial wetlands

The main factors that causes great environmental impacts are the use of fossil

fuels for the energy consumptions of the systems

The energy mix should contain more percentage of renewable sources. There is

a significant change concerning the coal brown energy (2013-48%, 2016-28%)

that reduced the environmental impacts from all the WWTPs function

LCA Stage IV: Interpretation


The basic prerequisite for the incorporation of LCA in the environmental permitting process are the following: The creation of an assessment method relevant to quality, validity and completeness of the

inventory data. The formation of a group of experts. The National database to be completed with all the data needed for the LCA procedure The development of an open-source LCA software. The normalization stage should be included as obligatory stage Organization of educational seminars in all levels (inhabitants, scientific community, authorities) Energy resources as clean as possible

For future research it would be interesting to apply the LCA method to different scale WWTPs (e.g.centralized) in order to provide a complete picture of its use.

ConclusionsThe application of LCA highlights the actions that should be implemented toimprove WWTP design focusing on the minimization of pollutant emission and theoptimization resources management . Technology improvements have significantlyoptimized WWTP operations.


Thank you for your attention!

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