Blue Flags, Black Water: The Sewage Treatment Plant in Italy’s Lignano Sabbiadoro

Lignano Pineta drone photo
Blue Flags, Black Water: The Sewage Treatment Plant in Italy’s Lignano Sabbiadoro

Lignano Sabbiadoro is a city nicknamed "the Florida of Italy." It's not hard to see why, located as it is close to the northernmost point of the Mediterranean Sea, in the Italian region of Friuli, lying on a small peninsula between the Marano Lagoon and the open sea.

On one side is the lagoon, a landscape marked by tidal cycles and populated by unique species. On the other side, in contrast, is a long sandy beach, which is a destination for millions of tourists, ready to crowd the bars, restaurants and discos in the town. In the winter, about 8,000 people live here, but in the summer months, Lignano welcomes as many as 250,000 individuals in a single day.

In the tourist imaginary, and according to data collected over the long term, the quality of Lignano Sabbiadoro's marine waters is flawless; a fact that has merited the town 34 consecutive "Blue Flags." The Blue Flag is an annual award by the Foundation for Environmental Education (FEE) to seaside resorts that guarantee excellent environmental status and high-quality services during the tourist season. The Blue Flag -- the criteria of which have sometimes been questioned -- has an indisputable role in making a resort more attractive for tourism.

Recently, Lignano's reputation has been in danger of being tarnished by a dispute over the wastewater treatment plant that serves the town. The issue concerns the possibility that the sewage treatment plant is undersized and unable to properly treat the amount of sewage that flows into it during the summer months. The sewage treatment plant is located in the northern part of Lignano, close to the Marano Lagoon. Starting in 2004, work to bring the sewage treatment plant up to compliance with new environmental regulations kicked off an affair that highlighted all the difficulties of operating such a facility in the midst of the complex reality that is Lignano Sabbiadoro.

Lignano Sabbiadoro, the “Florida of Italy”

Thanks to an audacious branding operation ahead of its time, Lignano Sabbiadoro was coined the "Florida of Italy." The expression is even attributed to Ernest Hemingway, who allegedly enjoyed the Italian town greatly. In fact, it seems that the author of The Old Man and the Sea made no more than a brief appearance in Lignano Sabbiadoro, staying only a few hours. The reason for his visit concerned the possibility of a real estate deal that ultimately fell through. While the comparison with Florìda was not as successful as initially hyped, Lignano has nevertheless become a prominent tourist resort attraction.

This means Lignano has considerable seasonal fluctuation in its residency. In winter, the number of residents is comparable to that of a village; during the summer, the numbers can reach those of a medium-sized Italian city. It is for this reason that treatment facilities should be guaranteed for the equivalent capacity of 180,000 equivalent persons (EP).

EP or PE is a basic measure for calculating the amount of organic matter conveyed to the sewer over a 24-hour period. In order to obtain the final number, opportune distinctions are made between permanent residents, seasonal residents, and short or daily presence. Today the sewage treatment plant operates with a capacity of 86,400 EP.

Escherichia coli contamination

Through the sewer system, effluent flows to the sewage treatment plant; once treated, it is discharged into the open ocean, about six kilometers offshore. But it is near the beach, about a hundred meters from the coast, that on June 14 of last year, staff from the regional environmental protection agency discovered the presence of 1013 cfu/100 ml of Escherichia coli [Colony Forming Unit, the unit of measurement for estimating the number of bacteria in a sample], more than double the Italian legal limit, which is set at 500 cfu/100 ml. Escherichia coli, or E. coli for short, and intestinal enterococci are the main indicators of fecal contamination of water bodies. This is why they are two of the parameters considered in recreational water monitoring. 

The event caused the City of Lignano Sabbiadoro to issue an urgent ordinance prohibiting swimming in its coastal waters starting the next day, June 15. Following a subsequent inspection that found the nearby ocean to be E. coli-free, the ordinance was lifted and people were able to dive back into the sea free of worry. Despite its brevity, the affair nonetheless sparked new interest in the town’s sewage treatment plant. According to experts interviewed by Radar, this plant may be one of the sources of E. coli detected in the waters of Lignano Sabbiadoro.

treatment plant
Lignano Sabbiadoro sewage treatment plant, July 5, 2023 / Credit: Diego Lorenzo Zanitti & Gianluca Liva.

Lignano Sabbiadoro sewage treatment plant: Projects, variants and conflicts

In 2004, the task of designing Lignano's new sewage treatment plant was given to the company Noesis Italia Srl. "The purification plant, after the enactment of new regulations, had become insufficient in its capacity rating, and some fundamental modules were missing,” recalls engineer Paolo Pivato, who was process consultant for Noesis Italia in 2007.

“The organic load that generates water contamination, in fact, is given by carbonaceous substances, but also by nitrogenous and phosphate substances. For them, the sewage treatment plant had no treatment system, ” he adds.

"In Lignano the sewage system does not separately collect rainwater from domestic water, it does not separate them. For this reason, the sewage treatment plant -- and this is its merit -- already had a rainwater treatment line. But the condition of Lignano Sabbiadoro is exceptional, with great seasonal fluctuation. This is why it had become necessary to develop a modular plant, not ‘forced’ to treat the maximum load throughout the year. To achieve this goal, the project included several lots: four."

The project was to be implemented, lot by lot, by 2016 according to the needs and possibilities of the water service manager, which from 2012 onward had been the Consorzio Acquedotto Friuli Centrale (CAFC); that is, the company that manages the entire integrated water cycle of 83 municipalities, including Lignano.

The project variant

In 2012, CAFC signed a contract with Noesis Italia to manage the work on the first two lots. Everything seemed to be going well until Noesis Italia and CAFC disagreed on a strategy to "merge" the first two lots into one, a project variant that would save time and money. Shortly thereafter, between 2014 and 2015, the parties came into conflict and, subsequently, into court. In 2015 CAFC decided to terminate the contract for non-performance, but in 2019 the court ruled that it had been an unlawful termination.

Marano Lagoon
The Marano Lagoon, as seen from above the spillway on Via Lovato, near the sewage treatment plant, Lignano Sabbiadoro, June 14, 2023 / Credit: Diego Lorenzo Zanitti & Gianluca Liva.
Spillway into the lagoon near the water treatment plant building, Lignano Sabbiadoro, July 4, 2023 / Credit: Diego Lorenzo Zanitti & Gianluca Liva.

Work on the sewage treatment plant -- which is still operating under a permit with prescriptions -- has proceeded slowly and has not yet been completed. Currently, CAFC claims that the sewage treatment plant is already capable of meeting the needs of the residents of Lignano. On the other hand, there are those who say that the upgrade of the Lignano sewage treatment plant, which has only been partially completed, is not sufficient and fails to treat the amount of effluent it should.

The law regulating urban wastewater discharges from high seasonally fluctuating agglomerations stipulates that sewage treatment plants should be sized according to the maximum foreseeable load, calculated on the basis of statistical data from tourist influx for the week of maximum presence. During the summer, it is not uncommon for Lignano to see more than 200,000 people frollick together for several consecutive days, so it would stand to reason that the plant should be sized accordingly. 

Rain and politics in the lagoon

Local politicians -- from several sides -- have also taken an interest in the affairs of Lignano's sewage treatment plant. Graziano Bosello, who in February 2023 was elected regional secretary of the right-wing Lega political party, said in 2019 that "since 2004, when 4 million euros was recovered for the work, 15 years have passed and the plant has still not reached the expected functionality. Over the years, mechanisms have been triggered that have prevented the construction of a facility adequate to Lignano's needs."

Cristian Sergo, Udine territorial coordinator of the transpartisan Five Star Movement, has also focused attention on the issue. "The Lignano sewage treatment plant is authorized to treat 1,800 cubic meters per hour. It does this through two lines: a 600 line and a 1,200 line. The 1,200 one is the line that was completed in 2015 and was supposed to have two sedimentation tanks available, both 600 cubic meters per hour. They built one in 2015, as planned," Sergo explains.

"In the acceptance tests it says that instead of making 600 cubic meters per hour (m³/h), the sedimentation tank makes about 364 (m³/h). In 2018 they did a detour of effluent to allow the effluent coming out of the 1,200 line to be purified in the large circular sedimentation tank that already exists. But this cannot treat more than 900 (m³/h). So the maximum capacity of the treatment plant is 1,264 (m³/h), and not 1,800, as authorized to treat," he says.

Heavy rains can also put pressure on sewers, to the point of threatening hydraulic safety. This is when spillways, technological artifacts that allow excess water to be vented into the environment, are opened. This is an uncommon activity and one that must be conducted with great care. In fact, once it enters the pipes, rainwater collects and expels debris that has accumulated during a dry spell. This water, as a result, turns out to have a non-negligible organic load.

The Lignano sewage treatment plant is prepared to deal with such eventualities, as it is equipped with a "first rain" treatment plant. Despite this, one of the problems that seems to exist in Lignano comes from the fact that there have been overflow openings in the lagoon even during periods of drought. "The problem in Lignano is that the spillway into the lagoon is activated even when it is not raining," Sergo points out. This is an assertion confirmed by various direct testimonies and by comparing rainfall data with data on the days the spillway is open.

shells and trash
Shells and solid waste in sediments near the sewage treatment plant during low tide, Lignano Sabbiadoro, June 14, 2023 / Credit: Diego Lorenzo Zanitti & Gianluca Liva.

The quality of the water and the lagoon

The bodies and authorities that oversee the sewage treatment plant assess the situation differently. Authorization for discharge activities is issued by the Water Resources Management Service of the Friuli Venezia Giulia Region. Paolo De Alti, director of the agency, clarifies that "the events at the Lignano sewage treatment plant are not related to a real environmental problem. In the last five years, there have been very few overflows. Although during the months with more tourists it is 'stretched by the neck’ and is at the limit, the purifier is doing its job."

The plant, moreover, would play a marginal role in determining the pollution situation present in the Marano Lagoon. The lagoon, in fact, represents an extremely complex system, on which many pressures act, from chemical industries to the presence of nearby livestock. Compared with all these pressures, the impact of the purifier would seem to be minimal.

"The sewage treatment plant has no effect on the lagoon. It may be true that occasionally the plant has to discharge into the lagoon, but it is still water with a very diluted pollutant load. To say that the environmental conditions of the lagoon -- good or bad -- are determined by the Lignano sewage treatment plant is a fallacy," De Alti argues.

Whatever their origin, the presence of bacteria in the lagoon is a fact. E. coli has been found in bivalve molluscs that are fished in some areas of the Marano Lagoon several times in recent years. Whenever this has occurred, the Health Authority's Prevention Department has issued an ordinance prohibiting human consumption of shellfish. As of writing, the last of these ordinances is dated August 11, 2023.

Red buoy and view of the Adriatic Sea; the sewage treatment plant discharge pipe runs on the seabed here, Lignano Pineta, June 14, 2023 Credit: Diego Lorenzo Zanitti & Gianluca Liva.

A matter of method

Doubt remains when looking at the data sets on the presence of E. coli and intestinal enterococci at the six locations where the regional environmental protection agency collects bathing water samples. There is very little overstepping of the legal limits; there have been only two times where this has occurred since 2010: September 5, 2011 and June 14, 2022. However, the presence within the detection limits of the two markers is almost constant. Sometimes the values are low, other times they border on the 500 cfu/100ml limit. Water sampling takes place once a month, from April to September, at each of the six points. Is this an effective method for establishing with some confidence that the water is, in general, clean?

"The method is not perfect. Escherichia coli monitoring is difficult and very complex. They are sometimes elusive organisms that can reproduce lightning-fast or disappear just as quickly. The variations are very wide and fast," De Alti says, "In the past, there have been cases where there were high values of Escherichia coli and then we authorized the use of peracetic acid [peroxyacetic acid, a very powerful antiseptic and antibacterial agent - ed.] with which to treat the effluent before it is released into the sea pipeline."

"But these were contingent situations: peracetic acid is a pollutant and should be used with great caution," De Alti points out. "We used a dosage that ensured that the effect of the substance was exhausted before it left the discharge into the sea. In general, however, it is good to remember that people can stay relaxed: in the sea of Lignano one can swim with confidence."

Events like the one in Lignano Sabbiadoro exemplify how difficult it is to design and monitor a purification system embedded in a delicate environmental context. In an area such as the CAFC's jurisdiction, where there are hundreds of sewage treatment plants, it would be necessary to make an overall assessment of any frailties in this intricate system of canals, pipes, purifiers and drains.

Increased environmental sensitivity may lead to scenarios that, until a few years ago, would never have been the subject of such heated discussions. At the same time, the events in Lignano shine a light on how difficult it is throughout the entire country for institutions to oversee the health of the environment, and how they must often come to terms with inadequate or poorly distributed resources.

lignano pineta dock
View of Lignano Pineta. Above, on the right, the Marano Lagoon, Lignano Pineta, June 14, 2023 / Credit: Diego Lorenzo Zanitti & Gianluca Liva.


This story was produced with support from Internews’ Earth Journalism Network. It was first published on August 11, 2023 in Radar Magazine and has been lightly edited for length and clarity. 

Banner image: In the center of the image, ARPA FVG sampling point IT006030049005, named "Pontile Pineta," Lignano Pineta, Italy, June 14, 2023 / Credit: Diego Lorenzo Zanitti & Gianluca Liva.

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