Frielas Wastewater Treatment Plant, Lisbon, Portugal

Serving a quarter-million Portuguese, StreamLine® system upgrade improves SOTE, energy savings, and effluent quality

Project Information

Location: Lisbon, Portugal
The plant is owned by Loures SMAS and is operated and managed by SIMTEJO, which is a government owned company integrated with Aguas de Portugal (also known as Aguas do Tejo Atlantico).
Plant Built: 1997
Population: 250,000+
System: EDI FlexAir Streamline
Project Type: Municipal Wastewater Treatment
Discharge Type: Environmental
The plant discharges to Ribeira da Póvoa, a small branch of the River Trancão.
Total treatment capacity: 700,000 Population Equivalent (PE).
The plant has a normal flow rate of 6,000 m³/h (3,530 cfm)

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Project Background & Challenges

In 2012, the Frielas WWTP authority decided to upgrade the equipment and optimize the aeration process of the plant for energy efficiency. The treatment scheme is based on a conventional activated sludge system with six 4,000m³ (141,259 ft³) complete mix biological reactors and 12 rectangular settlers.

The EDI Answer

EDI upgraded three of the six continuous activated sludge reactor lanes at the plant through three subsequent projects in 2012 and 2014; all with the high efficiency EDI FlexAir™ StreamLine® diffused aeration system.

The plant authority engaged two different main process contractors for the plant upgrade: Degremont (Now Suez) and Royal Haskonig DHV. After evaluating offers from aeration suppliers, process contractor companies unanimously selected the EDI StreamLine panel diffusers as the best aeration system.

StreamLine’s proven design elevates the industry’s standard practice by minimizing in-basin piping and attached diffuser components. The self-contained EDI FlexAir™ Panel Membranes and the in-line support system reduce stress points and potential material fatigue.

The aeration system was installed in the reactor tanks with a water depth of approximately 6.2m (20.34 ft). The innovative integral diffusers, tubular membranes, in-line support components, and the unparalleled structural integrity made the StreamLine aeration solution best suited for the tank depth and plant conditions. PVC plastic piping was used for the Fixed-Grid lateral system at the Frielas plant and the diffusers were designed with PU (Polyurethane) membranes for maximum efficiency and membrane life expectancy. The patented configuration of the StreamLine system ensured a swift installation as compared to competing panel systems.

Upgraded System Performance

The Frielas wastewater treatment plant upgrade exceeded its SOTE requirement, saved energy, and improved effluent quality.

The StreamLine system’s geometry supports a low flux rate, resulting in ultra-high Oxygen Transfer Efficiency performance.

After the upgrade, the oxygen transfer requirements were proven with off-site tests. An SOTE of 38.5% was achieved, surpassing the the requested SOTE of 37.75%, an efficiency of ~6.6% per meters.

The aeration diffusion system at the reactor tanks, fed by four centrifugal blowers, provide high OTE. The StreamLine panels showed a large energy savings and a reduced air pressure from the blowers.

Mr. Paulo Inocêncio, the SIMTEJO Operations Manager and Head of Operations at the Frielas WWTP, noted that water quality at the discharge to the River Trancao has significantly improved after the installation of EDI StreamLine aeration system.

“The Frielas Wastewater Treatment Plant has operated and put into use the StreamLine tubular diffusers for tank depth exceeding 6 meters. The diffusers are working well, with high ratio of oxygen transfer, ensuring technical requirements and process technology of the plant.
We are satisfied with the aeration system supplied by Environmental Dynamics International, Inc. (EDI) and we appreciate their service.”

– Paulo Jorge Inocêncio, Head Operator


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