Benchmarking large municipal WWTPs using official questionnaires: The case study of Italy

1. Benchmarking large municipal WWTPs using
official questionnaires: The case study of Italy
Sabino De Gisi, Luigi Petta, Roberto Farina
2ND IWA SPECIALIZED CONFERENCE "ECOTECHNOLOGIES FOR SEWAGE TREATMENT PLANTS”
Technical, Environmental & Economic Challenges
23-25 June 2014, Verona, ITALY

2. Framework
• Introduction
• Benchmarking water sector
• The link between plant’s quality and investments
• The aim of the study
• Materials and methods
• Framework of the proposed methodology
• Results and discussions
• Assessment of the municipal WWTPs quality for each Italian
District
• Identification of critical WWTPs and their processes
• Simulation of WWTPs improvements quantifying the results
of the proposed upgrade
• Conclusions
• References

3. Introduction
Benchmarking water sector
• In the past 20 years, several benchmarking projects have been
undertaken within water industry all over the world.
• In many occasions the drive to benchmark was initiated outside
the utility as in the cases of public debate about
liberalisation/privatisation of public services or else
requirements for large investments to improve the
service in terms of coverage and quality (Cabrera et al.,
2011).
• Regards this last aspect, a recent study conducted in Italy on a
sample of 112 water utility companies, highlights that the
total required investment in the Integrated Water Service
(IWS) amounts to almost 29 billion euro corresponding
to 715 euro per inhabitant (Co.N.Vi.R.I., 2011).

4. Introduction
The need for investment in the water sector…
• The evaluation of the IWS investment requirement is an
issue of great importance worldwide which makes a
benchmarking method an essential tool to be
implemented.
… overcoming the fragmentation of existing data
• With reference to a large spatial area such as a country, the
evaluation of plants quality level is generally hampered
by (i) the large number of plants to be compared, (ii) the
incompleteness of the available data and (iii) the different
sources to be considered (De Gisi et al., 2013).
• In order to achieve a good compromise, the use of official
questionnaires such as those provided by the Italian
National Institute of Statistics (ISTAT) can be considered
a suitable solution.

5. Introduction
The link between plant’s quality and investments
• Firstly, evaluating investments concerns the assessment
of the quality state of IWS components which includes
aqueducts, sewers, drinking water supply facilities and
municipal wastewater treatment plant.
• Subsequently, all those elements characterized by
critical issues ( e.g g. a p process in a )
WWTP) are
identified.
• The definition of a Sectorial Action Plan for the
improvement of the facility performance and the
subsequent planning of their interventions over time
are the other two phase.
Quality Assessment
of the Integrated
Water Service (IWS)
infrastructures
Investments
Estimation
in the field of IWS
Planning and
Interventions
Implementation
Fallout on the socio-economic-environmental
context and land use
management

6. The aim of the study
• The aim of the work is to develop and apply a planning
support tool working in the field of municipal
wastewater treatment plants (WWTPs). Based on the
philosophy of continuous improvement (Plan-Do-Check-Act
cycle, PDCA), the tool allows to:
• Assess the overall efficiency of WWTPs as well as identify
plants with environmental and technological critical issues
through the use of specific performance indicators as described below;
• Propose appropriate technical solutions through the definition of
Action Plans aimed at improving WWTPs efficiency;
• Simulate WWTPs improvements quantifying the results of the
proposed upgrade (the post-operam assessment of the Action Plans
previously defined) and, finally,
• Extend the results of the evaluation of WWTPs efficiency on a
regional scale comparing the performance of each single
District (corresponding to a “Region” in Italy) in terms of specific
indices (technological equipment, legal requirement compliance,
treatment capacity).

7. Materials and methods
Framework of the proposed methodology
• The first phase (PLAN) aims to evaluate the quality of WWTPs according to the
10 steps shown below;
• The second step (DO) is aimed at defining the improvement actions that will be
implemented in order to have a more efficient system;
• The third phase (CHECK) is aimed at measuring the WWTPs performance after
the implementation of the improvement actions;
• The fourth phase (ACT) is aimed at defining any new measures to be taken in
order to further improve the system.

8. Materials and methods
The first phase (PLAN): framework

9. Materials and methods
Proposed methodology: data input
Outlet WW
Flow-rate, BOD5, COD, Ntot, TSS, Ptot
WWTP Performance
Influent WW Flow-rate, BOD5, COD, Ntot, TSS, Ptot
WWTP Flow-chart water line
1 2
3 4
6
7 8
9 10 11
Bar Screens
Grit Chamber
Primary Settling Tank
Denitrification
Oxidation / Nitrification Tank
Secondary Settling Tank
Biofiltration (BFs)
Return Activated Sludge
5
Primary Sludge
Secondary Sludge
Disinfection
ISTAT survey (2008)
ƒ Large WWTPs (PE > 50,000)
ƒ Values for each month of sampling, on
annual basis

10. Materials and methods
Proposed methodology: data validation
Data acquired
(concentrations, flow-rate,
Population equivalent,
Industrial percentage…) with
the ISTAT questionnaire are
true?
The WWTP’s flow-chart
is in line with that
present in the system?
Open questions ….

11. Example of use of aerial photos to validate the WWTP’s flow-chart
Secondary sedimentation processes
Primary treatment
Secondary treatment for the removal
of organic matter
Disinfection
Pre-treatment
Effluent
Inlet WW

12. Materials and methods
Proposed methodology: performance indicators
N. Criteria N. Parameter Description and attribution of value to the parameter/sub-parameter
C1 Technological
equipment
C11 Primary and
secondary
treatment
With reference to the current technological equipment installed in the WWTP, are there primary and secondary treatments units (for
the removal of the organic substance)? Three classes were considered with correspondent qualitative and quantitative judgments: Class
1: Yes, with primary and secondary treatment (0.666); Class 2: Yes, with only primary treatment (0.500); Class 3: No, there is neither
a primary nor a secondary treatment (0.166). TO MAXIMIZE
C12 Treatments for
Nutrients removal
(Nitrogen and
Phosphorus)
With reference to the current technological equipment installed in the WWTP, are there treatments units for nutrients removal
(nitrogen and phosphorous)? Four classes were considered: Class 1: Yes, with nitrogen and phosphorus removal (0.875); Class 2: Yes,
only with nitrogen removal (0.625); Class 3: Yes, only with phosphorus removal (0.375); Class 4: No treatment unit is installed
(0.125).
TO MAXIMIZE
C13 Tertiary With reference to the current technological equipment installed in the WWTP, are there tertiary treatment units? Four classes were
treatments considered with correspondent qualitative and quantitative judgments: Class 1: Yes, with sand filtration and microfiltration (0.875);
Class 2: Yes, with only microfiltration (0.625); Class 3: Yes, with only sand filtration (0.375); Class 4: No treatment unit is installed
(0.125). TO MAXIMIZE
C14 Disinfection With reference to the current technological equipment installed in the WWTP, are there disinfection treatment units? Four classes were
considered: Class 1: Yes, with the use of technologies (UV, filter membranes, per acetic acid) more suitable with reference to the
minimization of the formation of DBPs (0.875); Class 2: Yes, with the use of ozone (0.625); Class 3: Yes, with the use of chlorine
compounds (chlorine gas, sodium hypochlorite) (0.375); Class 4: No treatment unit is installed (0.125). TO MAXIMIZE
C2 Environmenta
l performance
of the plant
C211 BOD5 With reference to the nitrogen concentration values in the effluent, according to the Italian and European legislation, how many cases
of non-compliant samples of BOD5 have been observed for each month of sampling, on annual basis? Four classes were considered
with correspondent qualitative and quantitative judgments: Class 1: number of non-compliant samples between 0-25% (inclusive),
(0.875); Class 2: number of non-compliant samples between 25-50% (inclusive), (0.625); Class 3: number of non-compliant samples
between 50-75% (inclusive), (0.375); Class 4: Number of non-compliant samples between 75-100% (inclusive), (0.125). TO
MAXIMIZE
C212 COD As for parameter C211, how many cases of non-compliant samples with respect to COD have been observed? TO MAXIMIZE
C213 TSS As for parameter C211, how many cases of non-compliant samples with respect to TSS have been observed? TO MAXIMIZE
C214 Total Nitrogen As for parameter C211, how many cases of non-compliant samples with respect to Total Nitrogen have been observed? TO MAXIMIZE
C215 Total Phosphorus As for parameter C211, how many cases of non-compliant samples with respect to Total Phosphorous have been observed? TO
MAXIMIZE
Part 1

13. Materials and methods
Proposed methodology: performance indicators
N. Criteria N. Parameter Description and attribution of value to the parameter/sub-parameter
C221 Percentage removal
of total nitrogen (%N)
With reference to the percentage removal of Total Nitrogen (% NTOT), according to the Italian and European legislation, how many
cases of non-compliant samples have been observed for each month of sampling on annual basis? Four classes were considered with
correspondent qualitative and quantitative judgments: Class 1: number of non-compliant samples between 0-25% (inclusive),
(0.875); Class 2: number of non-compliant samples between 25-50% (included), (0.625); Class 3: number of non-compliant samples
between 50-75% (inclusive), (0.375); Class 4: Number of non-compliant samples between 75-100% (inclusive), (0.125).
TO MAXIMIZE (a)
C222 Percentage removal
of total phosphorus
(%P)
As in the criteria C221, how many cases of non-compliant samples have been observed with reference to the percentage removal of
Total Phosphorous (% PTOT)? TO MAXIMIZE (a)
C223 Percentage removal As in the criteria C221, how many cases of non-compliant samples have been observed with reference to the percentage removal of
of BOD5 (%BOD5) BOD5 (% BOD5)? TO MAXIMIZE (b)
C224 Percentage removal
of COD (%COD)
As in the criteria C221, how many cases of non-compliant samples have been observed with reference to the percentage removal of
the COD (% COD)? TO MAXIMIZE (b)
C225 Percentage removal
of TSS (%TSS)
As in the criteria C221, how many cases of non-compliant samples have been observed with reference to the percentage removal of
TSS (% TSS)? TO MAXIMIZE (b)
C3 Treatment
capacity
C31 Domestic wastewater With reference to the rate of domestic influent wastewater, the treatment capacity of the plant is defined as the ratio of the Total
Effective Domestic Population Equivalent (PEtot, eff) and Total Design Domestic Population Equivalent (PEtot, design). The lower is the
value the greater is the residual capacity of treatment of the plant. In this way the costs for possible future interventions relating to
structural adjustment are reduced.
TO MINIMIZE
C32 Industrial wastewater As in the case of C31 criteria, but considering the rate of industrial influent wastewater.
TO MINIMIZE
C33 Treatment of tanker
wastewater
Treatment of tanker wastewater means the treatment of septic tanks or industrial plants, generally transported by tankers and then
processed in the system (i.e. via a special section) before being mixed into the influent wastewater or sludge line. The purpose of
such pre-treatment is to avoid overloads and alterations of plant operation. With reference to the current technological equipment,
the plant is able to treat the tanker wastewater?
YES = 0.75; NO = 0.25.
TO MAXIMIZE
Part 2

14. Materials and methods
Proposed methodology:
elaboration of the alternative matrix
Class 1: 0.666 (the best quality class for C11)
Class 2: 0.500 (the intermediate quality class for C11)
Class 3: 0.166 (the bed quality class for C11)
Presence of critical process for BOD5 removal
Need for upgrading actions

15. C11
WWTP Alternative i
m = number of sub-criteria/indicators
xij = performance of alternative i towards criteria j
IAi = improvement action
Step 1: performance indicators assessment and identification of critical processes for each single WWTP
C12 C13 C14
xi1 xi2 xi3
C211 C212
xi4 xi5 xi6
C213 C214
xi7 xi8
C215
xi9
C221 C222 C223
xi10
xi11 xi12
C224 C225
xi13 xi14
C31 C32 C33
xi15 xi16 xi17
IA1 IA2 IA3 IA4 IA1 IA1 IA1-3 IA2 IA2 IA2 IA2 IA1 IA1 IA1-3 IA5 IA5 IA6
Technological Equipment Index
(ITE)i
Environmental Performance Index
(IEP)i
Treatment Capacity Index
(ITC)i
Step 2: indices evaluation in order to reduce the amount of information for each single WWTP
More data aggregation
Lesser amount of information
Level 1 (Wastewater treatment plant scale)
S1
Sf
NSk
NS1
Sensitive WWTP (f = number of plants)
Non-Sensitive WWTP (k = number of plants)
S1
Sf
NSk
NS1
District
= +
IPDISTRICT, S
Level 2 (District scale)
WWTP Preference Index
(IP)i
ITEDISTRICT, S IEPDISTRICT, S ITCDISTRICT, S ITEDISTRICT, NS IEPDISTRICT, NS ITCDISTRICT, NS
IPDISTRICT, NS
Proposed methodology: WWTPs performance indices

16. Results and discussion
Simulation of the
WWTPs
improvements
quantifying the
results of the
proposed upgrade
3 GOAL
Assessment of the
municipal WWTPs
quality for each
wastewater
treatment plant
Assessment of
the municipal
WWTPs quality
for each District
1
GOAL 2
GOAL

17. Results and discussion
Technological Equipment Index
PLAN phase results
ITES
Technological
Equipment Index
Absence of data/WWTPs
Class 1
Class 2
Class 3
Class 4
Class 5 S-WWTPs
ITENS
Technological
Equipment Index
Absence of data/WWTPs
Class 1
Class 2
Class 3
Class 4
Class 5 NS-WWTPs
• Greater gap between North and South Districts above
all considering sensitive WWTPs.
• With reference to the South and Islands districts, we
have a good technological equipment for Apulia while
a bed value for the Campania district.

18. Results and discussion
Environmental Performance Index
S-WWTPs
Absence of data/WWTPs
Class 1
Class 2
Class 3
Class 4
Class 5 IEP
S
Environmental
Performance Index
IEP
NS
Environmental
Performance Index
Absence of data/WWTPs
Class 1
Class 2
Class 3
Class 4
Class 5 NS-WWTPs
• Greater gap between North and South districts
considering sensitive WWTPs.
• With referenc to the South and Islands districts, we
have bed perfromance both for the Campania both
for the Apulia.
PLAN phase results

19. Results and discussion
Treatment Capacity Index
ITCS
Treatment Capacity
Index
Absence of data/WWTPs
Class 1
Class 2
Class 3
Class 4
Class 5 S-WWTPs
ITCNS
Treatment Capacity
Index
Absence of data/WWTPs
Class 1
Class 2
Class 3
Class 4
Class 5 NS-WWTPs
• Greater gap between North and South districts above
all considering sensitive WWTPs.
• With reference to the South and Islands districts, we
have bed performance for the Apulia WWTPs becouse
of plants are overloaded.
PLAN phase results

20. Results and discussion
Preference Index
IP
S
Preference Index
S-WWTPs
Absence of data/WWTPs
Class 1
Class 2
Class 3
Class 4
Class 5
IP
NS
Preference Index
NS-WWTPs
Absence of data/WWTPs
Class 1
Class 2
Class 3
Class 4
Class 5
In brief:
• Greater gap between North and South above all
considering sensitive WWTPs.
• With reference to the South and Islands districts, we
have a bed overall value of the preference index for
the Apulia districts WWTPs.
PLAN phase results

21. Results and discussion
The case study of the Campania Region
Napoli EST Acerra
Sensible areas
Non sensible areas
Foce Sarno Area Salernitana
Manocalzati (Avellino)
Varolato (Capaccio)
PLAN-DO-CHECK-ACT phase results

22. Results and discussion
The case study of the Campania Region
1 2
4
5
6
3
Bar Screens
Grit Chamber
Chemical-physical
Disinfection
Primary chemical-physical Sludge
Primary Settling Tank
1 2
4
7
1) Napoli EST
5 6
8 9 10
3
Bar Screens
Grit Chamber
Chemical-physical
Oxidation Tank
Secondary Settling Tank
Disinfection
Return Activated Sludge
Secondary Sludge
Primary Settling Tank Primary Sludge
1 2
3
4 5
6
7 8 9
Bar Screens
Grit Chamber
Primary Settling Tank
Primary Sludge Secondary Sludge
Disinfection
Oxidation Tank
Primary sludge
Return Activated Sludge
2) Foce Sarno
3) Acerra
PLAN-DO-CHECK-ACT phase results

23. Results and discussion
1 2
The case study of the Campania Region
3 4
6
7 8
9 10 11
Bar Screens
Grit Chamber
Primary Settling Tank
Denitrification
Oxidation / Nitrification Tank
Secondary Settling Tank
Biofiltration (BFs)
Return Activated Sludge
5
Primary Sludge
Secondary Sludge
Disinfection
1 2
3
4
5
6
4) Manocalzati (AV)
Area 7 8 9
Bar Screens
Grit Chamber
Primary Settling Tank
Primary Sludge Secondary Sludge
Disinfection
Oxidation Tank
Primary sludge
Return Activated Sludge
1 2
3
4 5
6
7 8 9
Bar Screens
Grit Chamber
Primary Settling Tank
Primary Sludge Secondary Sludge
Disinfection
Oxidation Tank
Primary sludge
Return Activated Sludge
5) salernitana
6) Capaccio (Varolato)
PLAN-DO-CHECK-ACT phase results

24. Results and discussion
The case study of the Campania Region
From the Alternative Matrix (AM) to the
Criticalities Matrix (CM)
Identification of critical WWTPs and processes
PLAN-DO-CHECK-ACT phase results

25. Results and discussion
Upgrading actions scenarios
PLAN-DO-CHECK-ACT phase results

26. Results and discussion
Simulation of WWTPs improvements
Action Plan at District level
PLAN-DO-CHECK-ACT phase results

27. Conclusions
The implementation of the methodology lead to the following
results:
• Assessment of the overall plants efficiency also identifying those characterized
by environmental and technological critical issues;
• Implementation of technical solutions through the definition of appropriate
Action Plans aimed at improving the WWTPs efficiency;
• Development of the post-operam evaluation testing of the Action Plans
reliability, and, finally
• Extension of the results relating to the WWTPs efficiency evaluation on a
regional scale comparing the performance of the single Districts in respect to
specific indexes.
In addition:
• Our results demonstrate that the tool can be implemented using official data
such as those provided by the National Institute of Statistics (ISTAT) although
some verification is required;
• The developed case study shows the suitability of our proposal for
governmental institutions and water utilities companies in Italy, however it
could also be extended to other countries.

28. References
• Cabrera, E., Dane, P., Theuretzbacher-Fritz, H., 2011. Benchmarking Water Services: Guiding water utilities to
excellence. IWA Publishing, London, UK.
• Co.N.Vi.R.I., 2011. Status report on water services (Vol. 1). National Commission for Water Resources
Surveillance, Rome (in Italian).
• Council Directive 91/271/EEC of 21 May 1991 concerning urban waste-water treatment.
• D.Lgs. 152/2006. Decreto Legislativo 3 Aprile 2006, n. 152. “Norme in materia ambientale”, Gazzetta Ufficiale n.
88 del 14 Aprile 2006 – Supplemento Ordinario n. 96 (in Italian).
• ISTAT, 2008. Il Sistema delle Indagini sulle Acque. Anno 2008. ISTAT, Rome, Italy (in italian).
• ISTAT, 2012. Rapporto annuale 2012. ISTAT, Rome, Italy (in Italian).
• De Gisi, S., Petta, L., Farina, R., De Feo, G. 2014. Using a new incentive mechanism to improve wastewater
sector performance: The case study of Italy. J. Environ. Manage. 132, 94-106.
• Herva, M., Roca, E., 2013. Review of combined approaches and multi-criteria analysis for corporate
environmental evaluation. J. Clean. Prod. 39, 355-371.
• International Standard Organisation. ISO 14001 – environmental management systems – requirements with
guidance for use. International Standard Organisation, 2004.
• Lopez, A., Vurro, M., 2008. Planning agricultural wastewater reuse in southern Italy: The case of Apulia District.
Desalination. 218 (1-3), 164-169.
• Perotto, E., Canziani, R., Marchesi, R., Butelli, P., 2008. Environmental performance, indicators and
measurement uncertainty in EMS context: a case study. J. Clean. Prod. 16, 517-530.
• Romano, E., Bergamin, L., Finoia, M.G., Carboni, M.G., Ausili, A., Gabellini, M., 2008. Industrial pollution at
Bagnoli (Naples, Italy): Benthic foraminifera as a tool in integrated programs of environmental characterisation.
Mar. Pollut. Bull, 56 (3), 439-457.
• Valenzuela Montes, L.M., Matarán Ruiz, A., 2008. Environmental indicators to evaluate spatial and water
planning in the coast of Granada (Spain). Land Use Policy. 25 (1), 95-105.

29. Sabino DE GISI, Ph.D.
sabino.degisi@enea.it
Luigi PETTA, Ph.D.
luigi.petta@enea.it
Roberto FARINA, MSc
roberto.farina@enea.it
Italian National Agency for the New Technology, Energy and Sustainable
Economic Development, Water Resource Management Lab.
Via Martiri di Monte Sole 4, 40129, Bologna (ITALY)