Special Issue "The Impact of Treated Urban Wastewaters and Flood Discharge on the Quality of the Bathing Water"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Wastewater Treatment and Reuse".

Deadline for manuscript submissions: closed (15 May 2022) | Viewed by 14470

Special Issue Editors

Dr. Sabina Susmel
E-Mail Website
Guest Editor
Chemistry Section, Department of Agricultural, Food, Environmental and Animal Sciences (Di4A), University of Udine, via del Cotonifico 108, 33100 Udine, Italy
Interests: electrochemical and electromicrogravimetric sensors and biosensors; molecular imprinting (MIP) and immunoaffinity; environmental applications
Dr. Elisa Baldrighi
E-Mail Website
Guest Editor
Institute for Biological Resources and Marine Biotechnologies (IRBIM), National Research Council (CNR), Largo Fiera della Pesca, 2, 60125 Ancona, Italy
Interests: environmental quality assessment through benthic components (micro-, meio- and macrofauna); ecology and diversity of meiofauna and nematodes; microbial contamination in waters; micro–meio–macrofauna interactions in shallow to deep-sea systems
Special Issues, Collections and Topics in MDPI journals
Dr. Maja Krzelj
E-Mail Website
Guest Editor
Department of Marine Studies, University of Split, Ruđera Boškovića, 3721000 Split, Croatia
Interests: marine pollution; marine ecology; long term changes; climate change
Ms. Josipa Bilic
E-Mail Website
Guest Editor
METRIS Research Centre for Materials, Istrian University of Applied Sciences, Zagrebačka 30, 52100 Pula, Croatia
Interests: chemical analysis; microbiological analysis; water quality; biocompounds; biodegradation; biosensors
Dr. Viviana Scognamiglio
E-Mail Website
Guest Editor
Institute of Crystallography, National Research Council, AdR1, Montelibretti, Italy
Interests: algal biosensors; optical and electrochemical sensing; nanomaterials; environmental monitoring; medical diagnostics
Special Issues, Collections and Topics in MDPI journals
Dr. Mauro Celussi
E-Mail Website
Guest Editor
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale—OGS, 34010 Sgonico, Italy
Interests: aquatic microbial ecology; prokaryotes; biogeochemistry; C cycle; bacterial diversity

Special Issue Information

Dear colleagues,

This Special Issue rises in the framework of the two EU Interreg Italy–Croatia projects AdSWiM (www.italy-croatia.eu/web/adswim) and WATERCARE (www.italy-croatia.eu/web/watercare) and it will describe the impact of treated urban wastewaters and flood discharge on the quality of coastal waters.

The concentration of dissolved nutrients (e.g., nitrogen and phosphorus) in seawater is one of the most influential factors affecting life in the ocean. Often, human activities intervene by modifying the delicate nutrient balance through the discharge of treated wastewaters of both urban and industrial origin. As an effect of climate change, intense precipitation events are causing floods of rivers and streams, as well as sewage discharge and outfall flows posing significant threat to the environment. Such phenomena carry massive loads of land-derived and human-related materials to the coastal environments, including potentially pathogenic, faeces-associated microbes. The quality of bathing waters has received special attention from researchers and environmental policy makers due to the fact that many beaches are located near urban areas and indeed, they are subjected to high environmental pressure affecting both the ecosystem and human health.

With this Special Issue of Water, we would like to offer a platform for the presentation of innovative content regarding wastewater treatment technologies, analytical and microbiological control strategies regarding both the optimisation of analysis procedures and new devices for the analysis of sensors and biosensors, as well as proposals for the selection of new chemical and microbiological indicators for a rapid and/or effective verification of the characteristics of water that is discharged into the sea. Recent findings describing new predictive and modelling methods for wastewater and storm water runoff management and to support the governance decision-making process on the bathing water regulation are of high interest.

Kind regards,

Dr. Sabina Susmel
Dr. Elisa Baldrighi
Dr. Maja Krzelj
Dr. Josipa Bilic
Dr. Viviana Scognamiglio
Dr. Mauro Celussi
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Sensors and biosensors
  • Emerging pathogens
  • Innovative disinfection treatments
  • Advanced depuration technologies
  • Wastewater monitoring
  • Seawater protection
  • European directives
  • Microbial contamination
  • Rainfall events
  • Recreational waters
  • DSS (decision support system)

Published Papers (12 papers)

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Editorial

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Editorial
The Impact of Treated Urban Wastewaters and Flood Discharge on the Quality of Bathing Water
Water 2022, 14(16), 2552; https://doi.org/10.3390/w14162552 - 19 Aug 2022
Viewed by 489
Abstract
What do we know about the Adriatic Sea and the state of its health [...] Full article

Research

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Article
Impact of Depuration Plants on Nutrient Levels in the North Adriatic Sea
Water 2022, 14(12), 1930; https://doi.org/10.3390/w14121930 - 15 Jun 2022
Cited by 3 | Viewed by 1504
Abstract
Macronutrients (nitrogen—N; phosphorus—P; silicon—Si) play a crucial role in ocean surface waters stimulating the planktonic primary production; in fact, their concentrations are fundamental for the evaluation of the trophic status of the water body and eutrophication phenomena. Loads of nutrients into the sea [...] Read more.
Macronutrients (nitrogen—N; phosphorus—P; silicon—Si) play a crucial role in ocean surface waters stimulating the planktonic primary production; in fact, their concentrations are fundamental for the evaluation of the trophic status of the water body and eutrophication phenomena. Loads of nutrients into the sea are mainly represented by river runoff and depuration plant outflows. For this purpose, in the framework of the AdSWiM project, “Managed use of treated urban wastewater for the quality of the Adriatic Sea” levels of N-NO3, N-NO2, N-NH4, Si-Si(OH)4, P-PO4 (dissolved inorganic phosphorus—DIP) and total dissolved phosphorus (TDP) were determined colorimetrically at two sites in the Gulf of Trieste: Lignano Sabbiadoro and San Giorgio di Nogaro. For each site, during the bathing seasons of 2019 and 2020, a sample from the depuration plant (DP) outflow and another one in the bottom seawater near the discharging pipelines were collected. Results showed a strong dilution effect on nutrient levels passing from DPs to the sea, from one to three orders of magnitude and a low and not harmful concentration in seawater. The outflow composition of the two DPs showed that the main fraction of dissolved inorganic nitrogen (DIN) was represented by N-NO3 for Lignano, while in San Giorgio the major contribution came from N-NH4. Concerning phosphorus, Lignano showed a higher content (about 3 times) of P levels than San Giorgio, but a similar percentage composition, DIP:DOP (77:23), compared to the seawater site one DIP:DOP (2:98). Despite the difference between the DPs, no substantial differences were found in the sea sites, demonstrating the negligible effect of the DP outflows in the nutrient levels in the study area. Full article
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Communication
ADSWIM and WATERCARE Projects Meet Kids and Youth: The Challenge of Bringing the World of Research to School to Merge Research, Education and Communication
Water 2022, 14(12), 1843; https://doi.org/10.3390/w14121843 - 08 Jun 2022
Cited by 2 | Viewed by 1559
Abstract
The transfer of communication and knowledge from science and research to the general public is a paramount step to raise people’s awareness about environmental issues and their negative and positive impacts on each of us. Many projects and initiatives seek to raise awareness [...] Read more.
The transfer of communication and knowledge from science and research to the general public is a paramount step to raise people’s awareness about environmental issues and their negative and positive impacts on each of us. Many projects and initiatives seek to raise awareness among citizens, with particular attention to young people, about the importance of maintaining clean and healthy oceans. With this paper, we aim to present the successful communication initiatives developed during two Interreg projects, AdSWiM and WATERCARE, with schools and educational organisations on the local and national levels in Italy and Croatia. Both projects make a special effort to realize dedicated communication strategies with the objective of raising the awareness of environmental topics and issues among young people (i.e., students of different school grades) and teachers. The promotion of ocean literacy among students is crucial, as children and young people represent the future citizens and consumers who will develop attitudes and make decisions that will inevitably affect the environment. Full article
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Article
Metagenomic Characterization of Microbial Pollutants and Antibiotic- and Metal-Resistance Genes in Sediments from the Canals of Venice
Water 2022, 14(7), 1161; https://doi.org/10.3390/w14071161 - 04 Apr 2022
Cited by 1 | Viewed by 1048
Abstract
The spread of fecal pollutants and antibiotic resistance in the aquatic environment represents a major public health concern and is predicted to increase in light of climate change consequences and the increasing human population pressure on the lagoon and coastal areas. The city [...] Read more.
The spread of fecal pollutants and antibiotic resistance in the aquatic environment represents a major public health concern and is predicted to increase in light of climate change consequences and the increasing human population pressure on the lagoon and coastal areas. The city of Venice (Italy) is affected by diverse microbial pollution sources, including domestic wastewaters that, due to the lack of modern sewage treatment infrastructure in the historical city center, are released into canals. The outflowing jets of its tidal inlets thus represent a source of contamination for the nearby beaches on the barrier island separating the lagoon from the sea. Metagenomic analyses of DNA extracted from sediment samples from six sites in the canals of the city’s historic center were undertaken to characterize the microbial community composition, the presence of fecal microbes as well as other non-enteric pathogens, and the content of genes related to antibiotic (AB) and heavy metal (HM) resistance, and virulence. The six sites hosted similar prokaryotic communities, although variations in community composition likely related to oxygen availability were observed. All sites displayed relatively high levels of fecal contamination, including the presence of Fecal Indicator Bacteria, sewage- and alternative feces-associated bacteria. Relatively high levels of other potential pathogens were also found. About 1 in 500 genes identified at these sites are related to AB and HM resistance; conversely, genes related to virulence were rare. Our data suggest the existence of widespread sediment microbial pollution in the canals of Venice, coupled with the prevalence of ARGs to antibiotics frequently used in humans as well as of HMRGs to toxic metals that still persists in the lagoon. All of this evidence raises concerns about the consequences on the water quality of the lagoon and adjacent marine areas and the potential risks for humans, deserving further studies. Full article
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Article
Dissolved Potentially Toxic Elements (PTEs) in Relation to Depuration Plant Outflows in Adriatic Coastal Waters: A Two Year Monitoring Survey
Water 2022, 14(4), 569; https://doi.org/10.3390/w14040569 - 14 Feb 2022
Cited by 4 | Viewed by 879
Abstract
The Adriatic Sea is vulnerable to pollution due to its low bathymetry, intense industrial activity, and tourism. In this context, a good depuration plant activity could play a key role for the maintenance of a good environmental quality. In the framework of the [...] Read more.
The Adriatic Sea is vulnerable to pollution due to its low bathymetry, intense industrial activity, and tourism. In this context, a good depuration plant activity could play a key role for the maintenance of a good environmental quality. In the framework of the AdSWiM project, “Managed use of treated urban wastewater for the quality of the Adriatic Sea”, a study on dissolved potentially toxic element (PTE) levels was carried out to assess the impact of treated urban wastewaters on the quality of the bathing waters in the Adriatic Sea during the 2019 and 2020 summer period. In the present study, three areas along the Italian–Croatian coastline (Gulf of Trieste, Zadar, and Split) were identified for the monitoring of five depuration plant (DP) outflows. Water samples were collected after the treatment inside the DPs, and coastal seawater was sampled in the proximity of the discharging pipelines. Dissolved Hg, Cd, and As levels were determined with an atomic fluorescence spectrometer. Results did not show statistically significant differences between treated wastewater and seawater samples (Hg 10 ± 6 and 10 ± 4, Cd 14 ± 6 and 21 ± 8, As 610 ± 176 and 687 ± 140 ng L−1, respectively), while the geographical area and the seasonality affected the PTE concentration. Furthermore, the levels detected were lower than the European and national limits, indicating a good environmental status of the northern Adriatic Sea waters. The determination of further parameters (nutrients, microbiological indicators) must be investigated to identify possible synergistic effects. However, our results demonstrate the efficiency of DPs investigated, underlining the importance of the wastewater treatment for the protection of the Adriatic Sea. Full article
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Article
The Effect of Precipitation on the Microbiological Quality of Bathing Water in Areas under Anthropogenic Impact
Water 2022, 14(4), 527; https://doi.org/10.3390/w14040527 - 10 Feb 2022
Cited by 2 | Viewed by 750
Abstract
Intense rainfall can affect bathing water quality, especially in areas with poorly developed sewage systems or combined sewer overflows (CSOs). The aim of this study was to assess the impact of precipitation on coastal bathing water quality in the area of Split and [...] Read more.
Intense rainfall can affect bathing water quality, especially in areas with poorly developed sewage systems or combined sewer overflows (CSOs). The aim of this study was to assess the impact of precipitation on coastal bathing water quality in the area of Split and Kaštela (Adriatic Sea), the urban areas where CSOs were applied. The study was conducted during two bathing seasons, 2020 and 2021. The sampling of coastal waters and measurement of physical/chemical parameters was performed every two weeks and after a precipitation event of more than 2 mm. The impact of precipitation on the quality of coastal bathing waters was not noted in the Split area nor in Kaštela, probably due to the low amount of precipitation. The quality of bathing waters in the Kaštela area was significantly worse than in the Split area, which is due to the condition of the sewage system in these areas and not the precipitation effect. It was also revealed that bathing water quality depends on the timing of sampling and the indicator against which it is assessed. Escherichia coli (E. coli) proved to be a better indicator for early morning sampling, while intestinal enterococci were better for late morning sampling. Full article
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Article
Assessment of Spatio-Temporal Variability of Faecal Pollution along Coastal Waters during and after Rainfall Events
Water 2022, 14(3), 502; https://doi.org/10.3390/w14030502 - 08 Feb 2022
Cited by 4 | Viewed by 864
Abstract
More than 80% of wastewaters are discharged into rivers or seas, with a negative impact on water quality along the coast due to the presence of potential pathogens of faecal origin. Escherichia coli and enterococci are important indicators to assess, monitor, and predict [...] Read more.
More than 80% of wastewaters are discharged into rivers or seas, with a negative impact on water quality along the coast due to the presence of potential pathogens of faecal origin. Escherichia coli and enterococci are important indicators to assess, monitor, and predict microbial water quality in natural ecosystems. During rainfall events, the amount of wastewater delivered to rivers and coastal systems is increased dramatically. This study implements measures capable of monitoring the pathways of wastewater discharge to rivers and the transport of faecal bacteria to the coastal area during and following extreme rainfall events. Spatio-temporal variability of faecal microorganisms and their relationship with environmental variables and sewage outflow in an area located in the western Adriatic coast (Fano, Italy) was monitored. The daily monitoring during the rainy events was carried out for two summer seasons, for a total of five sampling periods. These results highlight that faecal microbial contaminations were related to rainy events with a high flow of wastewater, with recovery times for the microbiological indicators varying between 24 and 72 h and influenced by a dynamic dispersion. The positive correlation between ammonium and faecal bacteria at the Arzilla River and the consequences in seawater can provide a theoretical basis for controlling ammonium levels in rivers as a proxy to monitor the potential risk of bathing waters pathogen pollution. Full article
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Communication
A Detention Reservoir Reduced Combined Sewer Overflows and Bathing Water Contamination Due to Intense Rainfall
Water 2021, 13(23), 3425; https://doi.org/10.3390/w13233425 - 03 Dec 2021
Cited by 2 | Viewed by 821
Abstract
Combined sewer overflows (CSOs) close to water bodies are a cause of grave environmental concern. In the past few decades, major storm events have become increasingly common in some regions, and the meteorological scenarios predict a further increase in their frequency. Consequently, CSO [...] Read more.
Combined sewer overflows (CSOs) close to water bodies are a cause of grave environmental concern. In the past few decades, major storm events have become increasingly common in some regions, and the meteorological scenarios predict a further increase in their frequency. Consequently, CSO control and treatment according to best practices, the adoption of innovative treatment solutions and careful sewer system management are urgently needed. A growing number of publications has been addressing the quality, quantity and types of available water management and treatment options. In this study, we describe the construction of an innovative detention reservoir along the Arzilla River (Fano, Italy) whose function is to store diluted CSO wastewater exceeding the capacity of a combined drain system. River water sampling and testing for microbial contamination downstream of the tank after a heavy rain event found a considerable reduction of fecal coliform concentrations, which would have compounded the impact of stormwater on the bathing site. These preliminary results suggest that the detention tank exerted beneficial environmental effects on bathing water by lowering the microbial load. Full article
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Article
Antibiotic Resistance Genes and Potentially Pathogenic Bacteria in the Central Adriatic Sea: Are They Connected to Urban Wastewater Inputs?
Water 2021, 13(23), 3335; https://doi.org/10.3390/w13233335 - 24 Nov 2021
Cited by 7 | Viewed by 889
Abstract
Despite last decades’ interventions within local and communitarian programs, the Mediterranean Sea still receives poorly treated urban wastewater (sewage). Wastewater treatment plants (WWTPs) performing primary sewage treatments have poor efficiency in removing microbial pollutants, including fecal indicator bacteria, pathogens, and mobile genetic elements [...] Read more.
Despite last decades’ interventions within local and communitarian programs, the Mediterranean Sea still receives poorly treated urban wastewater (sewage). Wastewater treatment plants (WWTPs) performing primary sewage treatments have poor efficiency in removing microbial pollutants, including fecal indicator bacteria, pathogens, and mobile genetic elements conferring resistance to antimicrobials. Using a combination of molecular tools, we investigated four urban WWTPs (i.e., two performing only mechanical treatments and two performing a subsequent conventional secondary treatment by activated sludge) as continuous sources of microbial pollution for marine coastal waters. Sewage that underwent only primary treatments was characterized by a higher content of traditional and alternative fecal indicator bacteria, as well as potentially pathogenic bacteria (especially Acinetobacter, Coxiella, Prevotella, Streptococcus, Pseudomonas, Vibrio, Empedobacter, Paracoccus, and Leptotrichia), than those subjected to secondary treatment. However, seawater samples collected next to the discharging points of all the WWTPs investigated here revealed a marked fecal signature, despite significantly lower values in the presence of secondary treatment of the sewage. WWTPs in this study represented continuous sources of antibiotic resistance genes (ARGs) ermB, qnrS, sul2, tetA, and blaTEM (the latter only for three WWTPs out of four). Still, no clear effects of the two depuration strategies investigated here were detected. Some marine samples were identified as positive to the colistin-resistance gene mcr-1, an ARG that threatens colistin antibiotics’ clinical utility in treating infections with multidrug-resistant bacteria. This study provides evidence that the use of sole primary treatments in urban wastewater management results in pronounced inputs of microbial pollution into marine coastal waters. At the same time, the use of conventional treatments does not fully eliminate ARGs in treated wastewater. The complementary use of molecular techniques could successfully improve the evaluation of the depuration efficiency and help develop novel solutions for the treatment of urban wastewater. Full article
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Article
Spatial and Temporal Vertical Distribution of Chlorophyll in Relation to Submarine Wastewater Effluent Discharges
Water 2021, 13(15), 2016; https://doi.org/10.3390/w13152016 - 23 Jul 2021
Cited by 2 | Viewed by 1045
Abstract
The vertical distribution of chlorophyll in coastal waters is influenced by a combination of the hydrodynamic environment and different biotic and abiotic processes. The spatial and temporal occurrences of chlorophyll profiles provide a good representation of the changes in the marine environment. The [...] Read more.
The vertical distribution of chlorophyll in coastal waters is influenced by a combination of the hydrodynamic environment and different biotic and abiotic processes. The spatial and temporal occurrences of chlorophyll profiles provide a good representation of the changes in the marine environment. The majority of studies in the Adriatic Sea have so far been conducted in areas unaffected by anthropogenic pressure. Our study site is located near two marine outfalls, which are part of the public sewage system. This study aims to characterize the chlorophyll vertical distribution and describe its variability based on the stratification conditions and the presence of a wastewater effluent plume. Based on these conditions, we identified three characteristic scenarios/types of chlorophyll profiles. The first one occurs when the vertical mixing of the water column creates the upwelling of chlorophyll and nutrients to the upper part of the water column. The second and third scenarios occur during stratified conditions and differ by the extent of the effluent plume intrusion. Using modern fluorescence techniques, we identified and described three different vertical chlorophyll profiles, characterizing them according to their physical and biological parameters and processes. For cases with a visible effluent intrusion, we confirmed the importance of the pycnocline formation in keeping the effluent below and maintaining the higher water quality status at the top of the water column. Full article
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Article
Modelling the Quality of Bathing Waters in the Adriatic Sea
Water 2021, 13(11), 1525; https://doi.org/10.3390/w13111525 - 28 May 2021
Cited by 6 | Viewed by 1577
Abstract
The aim of this study is to develop a relocatable modelling system able to describe the microbial contamination that affects the quality of coastal bathing waters. Pollution events are mainly triggered by urban sewer outflows during massive rainy events, with relevant negative consequences [...] Read more.
The aim of this study is to develop a relocatable modelling system able to describe the microbial contamination that affects the quality of coastal bathing waters. Pollution events are mainly triggered by urban sewer outflows during massive rainy events, with relevant negative consequences on the marine environment and tourism and related activities of coastal towns. A finite element hydrodynamic model was applied to five study areas in the Adriatic Sea, which differ for urban, oceanographic and morphological conditions. With the help of transport-diffusion and microbial decay modules, the distribution of Escherichia coli was investigated during significant events. The numerical investigation was supported by detailed in situ observational datasets. The model results were evaluated against water level, sea temperature, salinity and E. coli concentrations acquired in situ, demonstrating the capacity of the modelling suite in simulating the circulation in the coastal areas of the Adriatic Sea, as well as several main transport and diffusion dynamics, such as riverine and polluted waters dispersion. Moreover, the results of the simulations were used to perform a comparative analysis among the different study sites, demonstrating that dilution and mixing, mostly induced by the tidal action, had a stronger effect on bacteria reduction with respect to microbial decay. Stratification and estuarine dynamics also play an important role in governing microbial concentration. The modelling suite can be used as a beach management tool for improving protection of public health, as required by the EU Bathing Water Directive. Full article
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Project Report
The Interreg Project AdSWiM: Managed Use of Treated Wastewater for the Quality of the Adriatic Sea
Water 2022, 14(16), 2460; https://doi.org/10.3390/w14162460 - 09 Aug 2022
Cited by 1 | Viewed by 753
Abstract
The Italy-Croatia Cross Border Cooperation (CBC) Programme is the financial instrument supporting the cooperation between the two European Member States overlooking the Adriatic Sea. The first call for proposals was launched in 2017, identifying four priority axes of intervention. Subsequently, in 2019, the [...] Read more.
The Italy-Croatia Cross Border Cooperation (CBC) Programme is the financial instrument supporting the cooperation between the two European Member States overlooking the Adriatic Sea. The first call for proposals was launched in 2017, identifying four priority axes of intervention. Subsequently, in 2019, the kick-off of the AdSWiM project “Managed use of treated urban wastewater for the quality of the Adriatic Sea” took place in Udine (IT). Adriatic marine waters are generally classified as good to excellent based on the Bathing Water Directive (2006/7/EC). Nevertheless, issues of low productivity or the lack of nutrients have been often suggested, especially on the Italian side. The project addresses the question of whether wastewater treatment plants (WWTPs) discharging to the sea, after applying appropriate pollution control and management technologies, can modulate the nutrient content of their effluents to support localized depleted areas. This idea is borrowed from one of the motivations that support the reuse of treated wastewater for irrigation, thus leading to the return of nutrients (nitrogen, phosphorus, potassium, etc.) to natural biogeochemical cycles. However, the hypothesis of modulating the nutrient composition of wastewater opens up to several critical aspects, including legislative and technological ones. Being aware of the delicate environmental implications, we have undertaken the project involving WWTPs, research centers, municipalities, and legal experts with the aim of investigating in detail the problems related to wastewater reuse, especially with regard to the content of nutrients. Our experimental approach aimed to evaluate appropriate and possibly new treatment technologies to reduce the microbial load and to implement chemical and microbiological tests on the treated wastewater. Results have shown that it can be tricky to draw decisive conclusions because (i) the wastewater management systems differ between the two sides of the Adriatic sea due to the different levels of technological development of WWTPs; (ii) the Italian and Croatian coasts deeply differ in geographic characteristics (i.e., topography, orography, current circuits, presence of rivers) and anthropogenic pressure (i.e., exploitation levels, population density); (iii) the new treatment technologies to lower bacterial contamination need further efforts to raise their technological level of readiness (TRL) and make them implementable in the existing WWTPs. However, in terms of chemical control methodologies, the proposed sensors and biosensors gave positive results, managing to decrease the detection limits for the measured parameters, and the tested technologies for microbiological monitoring were also effective. In particular, the latter was carried out by using recent molecular biology techniques, capable of resolving the microbiota in treated wastewater, which emerged to be strictly related to the features of the WWTPs. Full article
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