Last updated: November 2024
The Filter Ecosystem project, completed in 2007, aims to improve water quality and enhance the ecological health of the Molentargius wetland area in Sardinia, Italy, also known as the Molentargius Saline Regional Nature Park. This diverse territory includes freshwater basins such as Bellarosa Minore and Perdalonga, saline water basins like Bellarosa Maggiore and Stagno di Quartu, and the predominantly dry area known as Is Arenas. The Molentargius ecosystem is a crucial European site for various aquatic birds and features diverse flora, including endemic species and endangered plants on the "Red List." It is one of the few globally recognized wetlands of international importance for aquatic birds located entirely within a large urban center, protected as a biotope by the RAMSAR Convention in Sardinia's major urban area. Since the 1980s, it has suffered environmental degradation due to inadequate infrastructure for wastewater management and human pressures. Implemented by the city of Cagliari, the project employs a phytoremediation technique to supply water to the ponds. This involved constructing a phytoremediation system between the Bellarosa Maggiore and Bellarosa Minore ponds, functioning as a surface flow filter ecosystem resembling a marsh or wetland. The system enhances natural self-purification processes, promoting prolonged contact between water, organic matter, and plants. This setup creates microhabitats that support microbial flora crucial for purification. The project's primary goal is to treat wastewater from the Is Arenas treatment plant, ensuring that the treated water meets optimal conditions for sustaining the wetlands' biodiversity. Additionally, the project will expand reed bed areas, vital habitats for avian species, and is designed to purify up to 300 liters of water per second to meet the area's needs (Refs. 1, 2, 3).
Image of the Filter Ecosystem
Parco Molentargius. n.d. “Parco Naturale Regionale Molentargius-Saline.” Parcomolentargius.it. Accessed September 3, 2024. https://www.parcomolentargius.it/servizi/canali/1039.
Overview
Nature-based solution
- Blue infrastructure
- Coastlines
- Other
Key challenges
- Coastal resilience and marine protection (SDG 14)
- Marine and coastal biodiversity protection
- Environmental quality
- Soil quality improvement
- Green space, habitats and biodiversity (SDG 15)
- Green space creation and/or management
- Habitat and biodiversity conservation
- Water management (SDG 6)
- Improvements to water quality
- Water security
- Cultural heritage and cultural diversity
- Preservation of natural heritage
Principal problems in Functional Urban Area (FUA)
- Environmental Degradation
- Biodiversity loss
- Poor water quality
Key priorities
Biodiversity (conservation and/or restoration)
Focus
Creation of semi-natural blue areas, Creation of artificial wetlands, Coastal landscape management or protection, Coastal ecosystems restoration and maintenance (mangroves, dunes, saltplains, underwater meadows), Ecological restoration of ecosystems, Remediation activities of sites with very poor environmental quality, Restoration and protection of ecosystems (including water ecosystems), Protection of natural ecosystems, Protecton and enhancement of wetlands (other types than peatlands and mangroves, e.g. seagrass), Habitat conservation, Marine and coastal conservation initiatives
Project objectives
To improve the ecological health of the Molentargius wetlands by refining wastewater from the Is Arenas treatment plant using aquatic plants that naturally clean the water.
To enhance water quality by reducing organic substances, phosphorus, and nitrogen, ensuring optimal conditions for aquatic ecosystems.
To provide water that meets the natural needs of the Bellarosa Minore and Perdalonga areas, thereby preserving biodiversity and sustaining the energy flow throughout the entire food chain.
To maintain and protect the diverse flora and fauna of the wetlands and the coastal ecosystem they are part of, including rare and endangered plant species, by fostering an environment that supports a variety of plant life, from freshwater to salt-tolerant species.
To ensure the long-term sustainability and resilience of the Molentargius wetlands through a comprehensive approach that balances ecological health with water quality management.
Implementation activities
The "Filter Ecosystem" is a large phyto-purification plant, or rather an artificial wetland, built during the remediation works that exploits the self-purifying capacities typical of these environments to refine a part of the water coming from the Is Arenas purifier and make it suitable for feeding the ponds. The phytoremediation system was constructed over an area of approximately 37 hectares, which included 27 hectares of water surfaces. This system utilized natural processes involving aquatic plants to treat and enhance the quality of water flowing from the Is Arenas treatment plant.
To facilitate the movement of water throughout this system, several pumping stations were installed. The stations pumped treated water from the filtration system and distributed water to the Bellarosa Minore and Perdalonga basins.
A network of distribution pipes and channels was constructed to transport water from the treatment facility to various parts of the wetlands. This system included pressurized pipes and open channels, designed to minimize disruption to natural water flow and maintain the wetlands' hydraulic balance.
To further enhance local biodiversity, particularly for avian species, vegetation planting and habitat enhancement were carried out. This included establishing reed beds and other suitable vegetation, which were crucial for creating a self-sustaining ecosystem. These plants helped absorb nutrients, thereby reducing phosphorus and nitrogen levels in the water. (Ref. 1, 3)
Biodiversity conservation or restoration-focused activities
Biodiversity conservation:
- Protect and enhance urban habitats
- Create new habitats
- Reduce negative impacts and avoid the alteration/damage of ecosystem
- Protect species
- Undertake specific measures to protect endangered species
- Undertake specific measures to protect valued species
- Means for conservation governance
- Biodiversity offsets
- Manage biological resources for conservation and sustainable use
Main beneficiaries
- Citizens or community groups
Governance
Management set-up
- Co-governance with government and non-government actors
Type of initiating organisation
- National government
- Local government/municipality
Participatory approaches/ community involvement
- Co-planning (e.g. stakeholder workshops, focus groups, participatory mapping)
- Joint implementation (e.g. tree planting)
- Co-management/Joint management
Details on the roles of the organisations involved in the project
The Italian Parliament played a crucial role in the project's development by promulgating the law that provided the necessary funding. This legislative action established the financial and legal framework for the initiative (Ref. 8). The Ministry of the Environment was responsible for allocating these funds (Refs. 6 & 7).
The Metropolitan City of Cagliari oversaw the definition and supervision of the detailed operations to be implemented within the Molentargius Park. The Molentargius Park is managed by the Molentargius Saline Regional Nature Park Management Authority, which is a public body responsible for the park's administration and conservation. The park itself served as both a key stakeholder and a primary beneficiary of the project. Its management and administration actively participated in the implementation, ensuring that the project was integrated into the park's existing infrastructure while preserving its unique ecosystem (Refs. 1, 2 & 3).
Project implemented in response to ...
... an EU policy or strategy?
Unknown
... a national policy or strategy?
Yes
(The project was implemented in response to Law 67 of 11 March 1988, which the Italian government issued to establish investments in natural areas of international interest. The Law established funding for the metropolitan area of Cagliari to be coordinated with the Ministry of the Environment (Refs. 6, 7 & 8).)
... a local policy or strategy?
Yes
(In response to the distribution of funding in 1988, the Ministry of the Environment established a Safeguard Programme for Molentargius Park, which entailed a restoration of the park's water system in order to address the city's very serious sanitation situation. The process also implied the implementation of the natural ecosystem filter (Refs. 5 & 6).)
Type of enablers
Funds, subsidies or investment for GI/NBS in the city (available for the city or provided by the city)
Financing
Total cost
More than €4,000,000
Source(s) of funding
- Public national budget
Type of funding
- Direct funding (grants, subsidies, or self-financed projects by private entities)
Non-financial contribution
Unknown
Impacts and Monitoring
Environmental impacts
- Water management and blue areas
- Improved water quality
- Achieved improved water quality
- Enhanced protection and restoration of coastal and marine ecosystems
- Achieved enhanced protection and restoration of coastal and marine ecosystems
- Enhanced protection and restoration of freshwater ecosystems
- Achieved enhanced protection and restoration of freshwater ecosystems
- Green space and habitat
- Increased conservation or restoration of ecosystems
- Achieved increased conservation or restoration of ecosystems
- Increased presence and recovery of wild species
- Achieved increased presence and recovery of wild species
Economic impacts
- Unknown
Socio-cultural impacts
- Unknown
Type of reported impacts
Presence of formal monitoring system
Yes
Presence of indicators used in reporting
No evidence in public records
Presence of monitoring/ evaluation reports
No evidence in public records
Availability of a web-based monitoring tool
No evidence in public records
Potential risks of implementation and trade-offs
Unknown
References
1.
Parco Naturale Regionale Molentargius-Saline (n.d.). Ecosistema Filtro. Accessed on September 3, 2024, [Source link];
2.
Comune Cagliari News (2006). L'Ecosistema Filtro. Accessed on September 3, 2024, [Source link];
3.
Parco Naturale Regionale Molentargius-Saline (n.d.). OPERE FUNZIONALI AL TRATTAMENTO DI FITODEPURAZIONE E ALLA CIRCOLAZIONE IDRAULICA ACQUE DOLCI. Accessed on September 3, 2024, [Source link];
4.
MC-SALT (n.d.). RIQUALIFICAZIONE ECOSISTEMICA E NATURALISTICA ALL’INTERNO DEL PARCO MOLENTARGIUS - SALINE. Accessed on September 3, 2024, [Source link];
5.
Lo Ponte, M (2009). Bacini di trattamento e aree umide artificiali per la realizzazione di eco-sistemi filtro. Accessed on September 3, 2024, [Source link];
6.
Regione Autonoma della Sardegna (2004). deliberazione del 30.12.2004. Accessed on September 3, 2024, [Source link];
7.
Gazzetta Ufficiale della Repubblica Italiana (1979). DECRETO ASSESSORIALE 12 gennaio 1979 . Accessed on September 3, 2024, [Source link];
8.
Gazzetta Ufficiale della Repubblica Italiana (1988). Disposizioni per la formazione del bilancio annuale e pluriennale dello Stato. Accessed on September 3, 2024, [Source link];
9.
Comune di Cagliari (2022). Atlante Demografico di Cagliari 2022. Cagliari: Accessed on September 3, 2024, [Source link];
Information about this nature-based solution was collected as part of the Naturescapes project funded by the European Union under Grant Agreement No 101084341.