Increasing capacity and improving maintenance with Iso-Disc® at San Claudio Wastewater Treatment Plant

San Claudio EDAR (Wastewater Treatment Plant) is part of the sanitation system for the Nora river basin in Asturias, northern Spain. The existing wastewater treatment plant, which became operational in 1995, was designed for a biological treatment capacity of 110 litres per second, sufficient for a population of up to 26,000.

However, as the local population grew, the plant faced increasing challenges. Over the years, the existing facilities consistently received much higher influent flows and organic loads beyond their design capacity, resulting in operational inefficiencies. Recognizing the need for a modernized solution, the Spanish Ministry of Agriculture, Food, and Environment, along with the Cantabrian Hydrographic Confederation and the Principality of Asturias, initiated plans for a new wastewater treatment plant.

The Challenge

FCC Construcción-Aqualia was contracted to design, build, and operate a new facility that could meet the escalating demands of an ever-increasing local population. The objectives included:

• Expanding treatment capacity to 1,300 litres/second to serve a population of over 130,000 —five times greater than the previous plant.

• Complying with updated and stringent local environmental discharge regulations for the protected Nora River. Therefore, integrating new treatment stages within the same limited footprint as the existing structure.

• Selecting advanced yet easy-to-maintain filtration technology.

The Solution: Alfa Laval ASH Iso-Disc® Filtration Technology

To meet the project’s demanding specifications, ACUAES (Aguas de las Cuencas de España) selected Alfa Laval Iso-Disc® tertiary filtration technology. This solution offered a compact footprint, high filtration efficiency, and minimal maintenance requirements.

Alfa Laval provided two fully automatic Iso-Disc® cloth media filters, with space left for the installation of additional ASH Iso-Disc® filter units to meet increasing future throughput. Each unit consists of seven 900mm square filter elements, capable of filtering an average flow of up to 500m³/hour and handling peak flows of 800m³/hour. The filters were installed in concrete basins, with pumps, valves, and control panels positioned at ground level for easy access during operation and maintenance.

Results and Performance

Since their installation in 2016, the ASH Iso-Disc® filters have consistently delivered high-quality effluent, achieving suspended solids concentrations of <5 mg/L (95%ile), ensuring compliance with environmental regulations. The plant operators have praised the technology for its efficiency and ease of use.

According to Isabel Fanjul, San Claudio EDAR Plant Manager,

The filter cloth is cleaned by mechanical media without any chemicals, and it works automatically. The main advantage is the easy maintenance.”

Key Benefits

• Minimal Maintenance: The filters require no chemical cleaning; instead, a mechanical cleaning system automatically removes solids, reducing manual intervention.

• Operational Simplicity: The fully automated system allows plant operators to focus on broader operational tasks without frequent filter maintenance.

• Scalability and Flexibility: Additional ASH Iso-Disc® units can be seamlessly integrated as future capacity needs increase.