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Wastewater purification quality

In 2011, Hera managed sewage and wastewater purification services in 227 municipalities (of which 55 via Marche Multiservizi).
The sewage system managed by the company (excluding Marche Multiservizi) is approximately 14,135 kilometres long and is mixed (about 59% of the total). The length of the sewage system has increased by 2% following the drainage operations carried out (in 2011, 6,100 inhabitant equivalents were connected to the sewage system while work to connect another 1,900 inhabitant equivalents is ongoing). In 2012 another 17,000 inhabitant equivalents are expected to be connected. It is worth noting that while the sewage system has been extended, the length of the mixed network has been reduced (by 33 kilometres) because of the separation operations carried out in some areas.
Once again excluding Marche Multiservizi and considering only areas with over 2,000 inhabitant equivalents, in 2011 the sewage system covered 99% of the requirements in the territories (expressed as inhabitant equivalents, meaning the sum of resident inhabitants, production users transformed into inhabitant equivalents and presence due to tourism).

The Technical Round Table for the separation of the network and the Seawater Protection Plan

Hera participated in the Technical Round table of the Municipality of Rimini for the separation of the city's sewage systems. The related Plan was presented in early 2011: the operation complies with the European Directive that, by 2016, plans to reduce the pollutant load produced by waste water floodways in the networks by 70%. In December 2011 the local council approved the Seawater Protection Plan presented by Hera which, in the mid-term, would make it possible to completely close 70% of the pipes that discharge sewage into the sea, significantly reducing the frequency with which the others are opened.


Wastewater purification is carried out through 848 wastewater treatment plants, of which 15 have a capacity of over 100,000 inhabitant equivalents and 53 have a capacity of over 10,000 inhabitant equivalents. Considering areas with a nominal capacity of over 2,000 inhabitant equivalents, the purification service covers, excluding Marche Multiservizi, 99% of inhabitant equivalents in the area.
The Hera Group treated a total of approximately 293 million cubic metres of wastewater in 2011 compared to 341 million in 2010, a decrease of 14% caused by the reduction in the flow of rainwater.

 
Compliance of treated water with legally established limits (optimal values 100%)
 

The indicator relates to the plants with more than 10,000 inhabitant equivalents (the volumes treated in these plants equate to 81% of the total wastewater treated) and is calculated on the basis of the ratio between the concentration gauged for BOD5, COD, TSS, ammoniac nitrogen, phosphorus and total nitrogen and the related maximum concentrations permitted by Legislative Decree no. 152/2006 as amended. Bologna's plant limits are different from the regulation: ammonia nitrogen 25 mg/l; BOD5 40 mg/l; COD 160 mg/l; TSS 80 mg/l. For the Imola plant, where there is a final lagoon, the TSS limit is 150 mg/l.

The efficiency in removing pollutants in compliance with the legal limits, as expressed by the indicator in the graphic, is related to the purification capacity of the plant and the technologies adopted. The graphic shows that there was a slight reduction in quality in 2011 as a result of the ongoing adjustment works in some of the principal plants (mainly regarding the denitrification phase, which represents the most delicate phase of the biological purification process).
In 2011 the modernisation works at the Bologna, Bondeno (Ferrara), Cona (Ferrara), Formellino Faenza, Castel Guelfo (Bologna), Castelnuovo Rangone (Modena) and Savignano plants was concluded, the work at the Argenta (Ferrara), Forlė, Lugo (Ravenna), Granarolo (Bologna), San Giorgio di Piano (Bologna) and San Matteo della Decima (Bologna) plants continued, and modernisation work began at the Riccione plant.
Below are details on some of the work carried out in 2011.

  • At the Bologna treatment plant (900,000 IE) the works regarding the denitrification section, aimed mainly at improving the removal of nitrogen, were concluded. The work was concluded at the end of 2011 and its effects will be fully in evidence in 2012.
  • The work at the Bondeno (Ferrara) plant (10,000 IE) concluded in December 2011 while the Cona (Ferrara) plant was activated in June 2011 with an increase in capacity from 1,000 IE to 4,000 IE.
  • A disinfection sector was set up at the Formellino - Faenza plant (99,000 IE). Comparing the performances of the plant before and after the operation (October-December 2011 and 2010), the quality of outgoing water has improved by 19% in terms of COD and 5% in terms of BOD5.
  • In the second half of 2011 the Castel Guelfo plant (Bologna) went from 3,500 to 6,000 inhabitant equivalents and vastly improved its treatment performances: particular emphasis should be placed on the improvement of the quality of sewage in terms of the removal of organic substances, ammonia nitrogen and suspended solids. Comparing the figures for the period October-December 2011 with those of 2010, we can see that COD went from 52.8 to 15.5 mg/l (-71%), BOD5 went from 24.2 to 7.1 mg/l (-71%), total suspended solids went from 31.5 to 8.7 mg/l (-72%) and ammonia nitrogen went from 14 to 1 mg/l (-92%).
  • In the Castelnuovo Rangone (Modena) (44,000 IE) and Savignano (Modena) plants (8,000 IE) the ventilation systems were replaced with the installation of microporous plates driven by compressors: as a result of these operations energy consumption fell by 18% and 38% respectively.
  • At the Forlė treatment plant (250,000 IE), important structural adjustment works regarding the denitrification sector and other key sites were completed; the metal structural and electromechanic works are still to be carried out.
  • Important structural adjustment work has been carried out at the Lugo plant (270,000 IE): in 2011 an entire oxidative sector was excluded from the process for worksite reasons. At the Riccione plant (180,000 IE) significant structural adjustment work began in 2011.

For "organic" and odourless purification

On 16 April 2011 the Bacciolino di Mercato Saraceno (Forlė-Cesena) plant was opened, one of the most avant-garde in Italy. The treatment plant serves 15,000 inhabitant equivalents but can be further powered to serve 30,000. The plant organically purifies the water by passing the water flow through a bed of polystyrene foam marbles which, thanks to their highly elevated surface, notably increase the purification performance.


The following is scheduled for 2012:

  • the completion of modernisation works in the treatment plants of Argenta (Ferrara), Forlė, Lugo (Ravenna), Granarolo (Bologna), Riccione (Rimini), San Giorgio di Piano (Bologna) and San Matteo della Decima (Bologna) with an overall capacity of 754,000 inhabitant equivalents;
  • the start-up of work in the Cattolica (Rimini), Cesenatico (Forlė-Cesena) and Rimini S. Giustina (Rimini) treatment plants with an overall capacity of 460,000 inhabitant equivalents;
  • the investments foreseen for the drainage of the sewage network without purified sewage into the wastewater treatment plants for a total of 17,000 inhabitant equivalents.

This work will see 32 urban areas, corresponding to approx. 1.4 million inhabitant equivalents, brought into line with legislation.

 
Average annual concentrations at the main plants (2011)
mg/lBody of water receiving the purified wastewaterCOD (limit: 125 mg/l)BOD5 (limit: 25 mg/l)TSS (limit: 35 mg/l)Ammoniac nitrogen (limit: 15 mg/l)Volumes treated (thousands of m3)
IDAR (Bologna)Navile canal41.815.716.36.040,951
Anzola (Bologna)Scolo Sanguinettola Bassa or Scolo Lavinello23.65.68.21.01,355
Calderara (Bologna)Scolo Dosolo38.39.310.47.81,397
Ozzano (Bologna)Rio Marzano30.17.29.21.5531
S. S. Giovanni (Bologna)River Reno26.76.510.53.21,050
Gramicia (Ferrara)Po di Volano39.17.212.81.819,930
Cesena (Forlė-Cesena)Rio Granarolo17.85.16.80.66,654
Cesenatico (Forlė-Cesena)Scolo Madonnina56.75.022.94.33,425
Forlė (Forlė-Cesena)Scolo Cerchia24.75.110.51.713,684
Savignano (Forlė-Cesena)River Rubicone25.55.19.94.46,063
Faenza Formellino (Ravenna)River Lamone36.25.611.21.46,713
Imola Santerno (Bologna)River Santerno24.45.040.41.17043
ModenaNaviglio Canal27.06.114.50.836,419
RavennaCupa and Scolo Fagiolo Consortium canal22.02.87.21.315,832
Alfonsine (Ravenna)Scolo Sabbioni27.83.08.81.31,571
Bagnacavallo (Ravenna)Scolo Cappuccine22.62.67.40.61,185
Cervia (Ravenna)Cupa Consortium canal16.02.74.60.75,194
Lido di Classe (Ravenna)Pergami Canal11.52.75.60.9905
Lugo (Ravenna)Scolo Arginello39.85.710.13.87,065
Marina di Ravenna (Ravenna)Scolo Piombone14.92.55.40.51,447
Russi (Ravenna)Scolo Pisinello16.22.64.00.31,104
Rimini MarecchieseRiver Marecchia21.14.78.83.612,977
Rimini S. Giustina River Marecchia28.45.09.71.915,200
Riccione (Rimini)Rio Marano29.75.610.02.66,811
Cattolica (Rimini)Torrente Ventina27.44.913.22.66,379
Bellaria Igea Marina (Rimini)River Uso21.74.88.21.72,812
Pesaro Borgheria (Pesaro Urbino)River Foglia34.16.813.60.46,435
Total volume treated     230,130

The volume treated in the 27 plants indicated in the table equates to 78% of the total wastewater treated. Bologna's plant limits are different from the regulation: ammonia nitrogen 25 mg/l; BOD5 40 mg/l; COD 160 mg/l; TSS 80 mg/l. For the Imola plant, where there is a final lagoon, the TSS limit is 150 mg/l. For the Forlė-Cesena TOS the calculation does not include total nitrogen.

For the Group's 27 main purification plants (selected from those with a nominal capacity exceeding 10,000 inhabitant equivalents) the table sets forth the average outflowing concentrations of the most representative parameters, expressed in terms of COD, BOD5, TSS and ammoniac nitrogen.
The concentrations of the sewage parameters are in line with those of the previous years, with the exception of the ammonia nitrogen identified in the plants of Calderara (Bologna), Cesenatico (Forlė-Cesena), Formellino (Ravenna) and Lugo (Ravenna), where extraordinary events took place, and Riccione, where structural adjustment works are taking place.
Purification treatment sludge is considered special waste and must be managed according to Legislative Decree no. 152/2006. As regards the possibility of recovering part of the agricultural sludge, the reference regulation is Legislative Decree no. 99/1992; specific regulations for the Region of Emilia-Romagna are contained in resolution no. 2773/2004.
In 2011, the purification process produced about 42 kg of sludge per inhabitant equivalent served (the figure refers to the quantity of sludge disposed with an average dryness grade on the order of 18-28% and refers to areas with over 2,000 inhabitant equivalents).
The sludge reused directly in agriculture was almost 2% of the total, in line with 2010, with characteristics and management methods that complied with relevant national and regional legislation. The remaining sludge produced was managed through dedicated incineration (approx. 30,000 metric tons), transfer to landfills (approx. 65,000 metric tons) and indirect agronomic reuse, following composting (60,000 metric tons).

Constructed wetlands

Hera manages eight constructed wetlands plants of small or medium-small capacity in the provinces of Bologna, Ferrara, Florence, Forlė-Cesena, Rimini and Ravenna: some are secondary biological treatment plants downstream of primary sedimentation, others are third party treatments used for final refinement. The constructed wetlands process is a natural process for the treatment of polluted waters based on the exploitation of the soil-vegetation system as a natural filter for the purification of water, and is made up of a system of biological ponds and of macrophytic vegetation. This kind of treatment also contributes to the reclamation of borderline areas, creating natural environments and landscapes that are pleasing to the eye, and often chosen as refuges for various species of bird, amphibian and reptile. In these areas, it is therefore also possible to organise educational tours to observe specific animal and vegetable species typical of wetlands.