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

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

2ND IWA SPECIALIZED CONFERENCE "ECOTECHNOLOGIES FOR SEWAGE TREATMENT PLANTS”Technical, Environmental & Economic Challenges23-25 June 2014, Verona, ITALY

Sabino De Gisi, Luigi Petta, Roberto Farina

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

Introduction

• 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

Benchmarking water sector

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).

IntroductionThe 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 datag g g

• 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.

Introduction

• 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. a process in a WWTP) are

The link between plant’s quality and investments

( g p )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-

environmentalcontext and land use

management

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;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).

Materials and methodsFramework 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.

Materials and methodsThe first phase (PLAN): framework

Materials and methodsProposed methodology: data input

Flow-rate, BOD5, COD, Ntot, TSS, Ptot

Outlet WW

WWTP Performance

1 23 4

67 8

9 10 11

Bar ScreensGrit ChamberPrimary Settling TankDenitrification

Oxidation / Nitrification TankSecondary Settling TankBiofiltration (BFs)

Return Activated Sludge

5

Primary Sludge

Secondary SludgeDisinfection

Flow-rate, BOD5, COD, Ntot, TSS, PtotInfluent WW

WWTP Flow-chart water line

ISTAT survey (2008)Large WWTPs (PE > 50,000)Values for each month of sampling, on annual basis

Materials and methodsProposed 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 ….

Secondary sedimentation processes

Primary treatment

Example of use of aerial photos to validate the WWTP’s flow-chart

Secondary treatment for the removal of organic matter

Pre-treatment

Disinfection

Effluent

Inlet WW

Materials and methodsProposed methodology: performance indicators

N. Criteria N. Parameter Description and attribution of value to the parameter/sub-parameterC1 Technological

equipmentC11 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 Environmental 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 MAXIMIZEC213 TSS As for parameter C211, how many cases of non-compliant samples with respect to TSS have been observed? TO MAXIMIZEC214 Total Nitrogen As for parameter C211, how many cases of non-compliant samples with respect to Total Nitrogen have been observed? TO MAXIMIZEC215 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

Materials and methodsProposed methodology: performance indicators

N. Criteria N. Parameter Description and attribution of value to the parameter/sub-parameterC221 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 TotalEffective Domestic Population Equivalent (PEtot, eff) and Total Design Domestic Population Equivalent (PEtot, design). The lower is thevalue the greater is the residual capacity of treatment of the plant. In this way the costs for possible future interventions relating tostructural 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

Materials and methodsProposed 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

C11

WWTP Alternative im = number of sub-criteria/indicators

xij = performance of alternative i towards criteria jIAi = improvement action

xi1 xi2 xi3

C12 C13 C14

xi4 xi5 xi6

C211 C212

xi7 xi8

C213 C214

xi9

C215

xi10

C221 C222 C223

xi11 xi12

C224 C225

xi13 xi14

C31 C32 C33

xi15 xi16 xi17

IA1 IA2 IA3 IA4 IA1 IA1 IA1 IA1IA2 IA2 IA2 IA2 IA1-3IA1-3IA5 IA5 IA6

Step 1: performance indicators assessment and identification of critical processes for each single WWTP

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

Mor

e da

ta a

ggre

gatio

n

Less

eram

ount

ofin

form

atio

n

Sensitive WWTP (f = number of plants)Non-Sensitive WWTP (k = number of plants)

S1

Sf

NSkNS1

S1

Sf

NSk

NS1

District

= +

IPDISTRICT, S

Level 2 (District scale)

Level 1 (Wastewater treatment plant 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

Simulation of the WWTPs

improvements quantifying the results of the

proposed upgrade

Results and discussion

3 GOAL

Assessment of the municipal WWTPs

quality for each wastewater

treatment plant

Assessment of the municipal

WWTPs quality for each District

1

2GOAL

GOAL

Results and discussionTechnological Equipment Index

PLAN phase results

Absence of data/WWTPsClass 1Class 2Class 3Class 4Class 5 S-WWTPs

ITESTechnologicalEquipment Index

ITE NSTechnologicalEquipment Index

Absence of data/WWTPsClass 1Class 2Class 3Class 4Class 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.

Environmental Performance Index


S-WWTPs


IEPEnvironmentalPerformance Index

SIEPEnvironmentalPerformance Index

NS-WWTPs

NS


• 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

Treatment Capacity Index


ITCSTreatment CapacityIndex


ITCNSTreatment CapacityIndex


• 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

Preference Index


IP

S-WWTPs

SPreference Index

Absence of data/WWTPsClass 1Class 2Class 3Class 4Class 5

IP

NS-WWTPs

NSPreference Index

Absence of data/WWTPsClass 1Class 2Class 3Class 4Class 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

Napoli EST Acerra

The case study of the Campania Region


Non sensible areas

Sensible areas

Foce Sarno Area Salernitana

Varolato (Capaccio)

Manocalzati (Avellino)

PLAN-DO-CHECK-ACT phase results

1 24

5

6

3

Bar ScreensGrit ChamberChemical-physical

DisinfectionPrimary chemical-physical Sludge

Primary Settling Tank

1 24

7

1) Napoli EST



45 6

8 9 10

3

Bar ScreensGrit ChamberChemical-physical

Oxidation TankSecondary Settling TankDisinfection

Secondary SludgeReturn Activated Sludge

Primary SludgePrimary Settling Tank

1 23

4 5

6

7 8 9

Bar ScreensGrit ChamberPrimary Settling Tank

DisinfectionPrimary Sludge Secondary Sludge

Oxidation TankPrimary sludgeReturn Activated Sludge

2) Foce Sarno

3) Acerra


1 23 4

67 8

9 10 11

Bar ScreensGrit ChamberPrimary Settling TankDenitrification

Oxidation / Nitrification TankSecondary Settling TankBiofiltration (BFs)

Return Activated Sludge

5

Primary Sludge

Secondary SludgeDisinfection

1 23

4 5

6

4) Manocalzati (AV)

5) Area salernitana



4

7 8 9




1 23

4 5

6

7 8 9




5) Area salernitana

6) Capaccio (Varolato)




Identification of critical WWTPs and processes

From the Alternative Matrix (AM) to the Criticalities Matrix (CM)


Upgrading actions scenarios



Simulation of WWTPs improvements


Action Plan at District levelPLAN-DO-CHECK-ACT phase results

Conclusions

• 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

The implementation of the methodology lead to the following results:

• 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.

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.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.

Sabino DE GISI, Ph.D. [email protected]

Luigi PETTA, Ph.D. [email protected]

Roberto FARINA, MSc [email protected]

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)

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

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