An energy efficiency and effluent quality improvement project being carried out by the Spanish subsidiary of Veolia Water Technologies at the La Cartuja Wastewater Treatment Plant (WWTP) in Zaragoza will save 600,000 euros a year in energy costs on a total investment cost amounting to nearly 5 million euros.
The plant has a treatment capacity of 1,000,000 equivalent-inhabitants and serves Zaragoza and several neighbouring municipalities.
This improvement plan, which involves activities for a total investment of 5 million euros, is being undertaken by UTEDEZA, a company that belongs to the Veolia Group, which is in charge of operating the WWTP for the Ayuntamiento de Zaragoza.
The plan includes a total of seven actions aimed at improving energy efficiency at the WWTP, providing 600,000 euros in savings on the energy bill each year and improving the quality of the effluents discharged into the Ebro, reducing environmental impact during stormy weather.
For the actions in the environmental improvement section, the La Cartuja WWTP will be equipped with Veolia’s ACTIFLO® DUO process. This ballasted settling process using microsand was designed for a treatment capacity of 2.6 cubic meters per second that is first used for treating the excess water flow that reaches the plant during rain or storms before being released into the Ebro and for secondary scrubbing to remove suspended solids and ensure the right COD of the final effluent if the WWTP becomes overloaded.
The process will also be able to operate as a conventional MULTIFLO™ settler for the treatment of return water from top to bottom, optimizing operating costs and improving the process’s overall efficiency.
With regard to energy improvements, the main action being carried out by UTEDEZA is a change in the aeration system on the biological reactors to obtain 1.4 million kWh in energy savings a year. Another major action consists of the installation of a hydraulic turbine to make use of the 8.50 meter drop between the purified water outlet and the surface of the Ebro, which should generate some 685,000 kWh of energy a year.
Veolia said that in all, the plan of improvement actions should provide energy savings exceeding five million kWh a year while helping to improve the quality of the water released into the river by ensuring effluents that are up to standard.
Internationally, Veolia Water Technologies is one of the leaders in the design and construction of water treatment plants, with 2.1 billion euros in turnover in 2013 and employing over 10,000 people.
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