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Work to significantly upgrade the Mar Menor Sur wastewater treatment plant near Cartagena has moved a step closer, after the board of state-owned water company ACUAES authorised the signing of a formal agreement with the regional wastewater body ESAMUR and the Cartagena Ayuntamiento. The project carries a total investment of €15 million and will dramatically improve the quality of water discharged into the Mediterranean, while also producing high-quality reclaimed water for agricultural use.

 

The centrepiece of the upgrade is a new tertiary treatment system, capable of handling an average flow of 35,000 cubic metres per day and a maximum of 50,000 cubic metres. The system will incorporate a regulating tank, deep filtration and ultraviolet disinfection, and will be built on top of a rehabilitated primary treatment stage from the existing plant. The reclaimed water produced will need to meet Class A agricultural standards under current Spanish regulations, making it suitable for direct supply to local irrigators.

 

Beyond the main treatment system, the project also includes the replacement of ageing electromechanical equipment, improvements to the biological treatment aeration system, a new generator, and an acoustic barrier around part of the site perimeter.

 

The investment forms part of the wider Framework of Priority Actions for the Recovery of the Mar Menor, a programme backed by €675 million from the Ministry for Ecological Transition. The Mar Menor has been at the centre of sustained environmental concern for years, with wastewater management identified as one of the key pressures on the lagoon's fragile ecosystem, and new regional controls on coastal discharges already being prepared to tighten the rules further.

 

Funding is split equally: 50% comes from European Regional Development Fund money under the 2021-2027 cycle, while the remaining 50% will be advanced by ACUAES from its own reserves and recovered from ESAMUR via tariffs over a 30-year period. The Cartagena Ayuntamiento will provide the land and take on responsibility for the plant's ongoing operation and maintenance.

 

The actual tendering process for the construction work cannot begin until the formal agreement between the three parties has been signed. A second project to improve the Cabezo Beaza treatment plant in Cartagena is also in the pipeline, with its own agreement already approved by ACUAES and the Ayuntamiento and awaiting final processing by ESAMUR.

 

 

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