Benchmarking large municipal WWTPs using official questionnaires: The case study of Italy 2ND IWA SPECIALIZED CONFERENCE "ECOTECHNOLOGIES FOR SEWAGE TREATMENT PLANTS” Technical, Environmental & Economic Challenges 23-25 June 2014, Verona, ITALY Sabino De Gisi , Luigi Petta, Roberto Farina
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Benchmarking large municipal WWTPs using official questionnaires: The case study of Italy
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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
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
From the Alternative Matrix (AM) to the Criticalities Matrix (CM)
PLAN-DO-CHECK-ACT phase results
Upgrading actions scenarios
Results and discussion
PLAN-DO-CHECK-ACT phase results
Simulation of WWTPs improvements
Results and discussion
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).
• 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.
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)