Porto: Sobreiras and Freixo ETAR upgrades backed by €4.5 million

Modernisation of Porto’s wastewater treatment plants (ETAR)

Porto’s wastewater treatment plants (ETAR) at Sobreiras and Freixo are being upgraded. To speed up delivery, Águas e Energia do Porto has committed €4.5 million, aiming to strengthen the sites’ energy autonomy.

A central strand of the work is to refine the parts of the systems that account for a large share of the ETAR’s energy use, cutting unnecessary consumption while improving the efficiency of day-to-day plant operation.

ETAR do Freixo: biogas recovery and energy self-sufficiency

At the ETAR do Freixo, one of the key measures is to add value to the biogas generated during the wastewater treatment process by capturing the thermal and electrical energy produced and reusing it within the facility.

The scheme is due to be completed in the first half of 2027 and could enable the ETAR to reach around 60% energy self-sufficiency.

ETAR de Sobreiras: oxygen transfer tests and final works

Performance testing is currently under way to validate efficiency gains in oxygen transfer. At the ETAR de Sobreiras, the upgrade is now in its final stage, following the completion of the replacement of diffusers and mixers.