ACCIONA has begun the extension and renovation of its Wastewater Treatment Plant (WWTP) at Musquiz, the oldest in Vizcaya


ACCIONA has begun the extension and renovation of its Wastewater Treatment Plant (WWTP) at Musquiz, the oldest in Vizcaya, which has been in service since 1988. After the extension, the plant will treat a 30% higher throughput to reach 4,600 m3/day. 

The new plant will enter service in 2024, although the present one will continue to be operational during the renovation work. ACCIONA will also undertake the operation and maintenance of the renovated plant for one year after the extension has been completed.

The project, with a budget of €12.5 million, was awarded by the Bilbao Area Water Board (CABB) following a competitive dialogue procedure in which a number of bidders presented technical solutions prior to the definitive award.

The solution put forward by ACCIONA includes a new biological treatment system based on Nereda© technology, an innovative method in wastewater treatment developed by Delft University of Technology (Netherlands) that can be implemented in both new and existing facilities. In existing plants, this method increases treatment capacity and improves performance, making it an ideal solution for older installations, where more demanding process requirements lead to a high level of water consumption.

The new biological treatment system enables the simultaneous elimination of phosphorous, organic matter, ammonium and nitrates, together with a more compact design that reduces the need for additional surface area in the present plant. 

ACCIONA will also build a new pre-treatment phase, a tertiary treatment phase with filtration and disinfection, a storm water treatment unit and an installation to eliminate, dehydrate and store sludge. 

The new WWTP will also incorporate a new odour treatment process; new wastewater treatment networks; auxiliary facilities and networks, and a new electric power and control installation for the whole plant. The existing buildings will be renovated for different uses: as a building for supervision and visits, changing rooms, workshop and storage areas.

Furthermore, ACCIONA has applied the BIM (Building Information Modeling) methodology to create a full 3D model of the plant in the design phase. This will be later completed during the construction and operation of the WWTP.