Wastewater treatment plant in Tunisia

VA TECH WABAG (Austria) has received an order from the Tunisian wastewater authority, ONAS (Office National de l’Assainissement) for the planning and completion of the Hergla and Enfidha wastewater treatment plant. The project will involve a volume of over EUR 11 million and WABAG will serve as the leader of a consortium that includes the local construction company, MTT. The work is to be co-financed by the European Investment Bank (EIB).

Enfidha is located in north-eastern Tunisia, some 80km south of the capital and in the middle of the nation’s most important tourism area between Hammamet and Sousse. From 2010 onwards, the region will be increasingly frequented, as next year, the new international airport in Enfidha will commence operations with an initial capacity of 5 million passengers per year. In addition to the municipal wastewater from the towns of Enfidha und Hergla, the plant will also deal with the wastewater emanating from the airport.

The concept of the wastewater treatment plant incorporates conventional treatment technologies in the form of mechanical/biological processes. An automated screen system will be used for mechanical pre-treatment while an activated sludge system is to be employed for biological treatment. Downstream sludge treatment will then follow in the form of thickening and dewatering. The plant is designed for a capacity of 10,540 m3

of wastewater and a BSB5 freight of 4,200 kg/d, which corresponds with a p.e. value of 70,000. The cleaned wastewater will be discharged into the Mediterranean via a 1.5 km submarine duct. The two-stage plant technology employed will secure environmentally compatible wastewater disposal and represents a further contribution to water protection and the retention of the marine habitat. The wastewater plant will become operational at the end of 2010.