Oran, Algeria’s second largest city with a population of around 1.5 million and the main metropolitan area of the Oran coastal province, was not only the setting for the forthcoming OPEC conference last Wednesday, 16 December. Aside from world politics, on that day the highest government representatives of Algeria – President Bouteflika, Minister of Water Resources Mr Sellal and Interior Minister Mr Zerhouni, together with other representatives of the Algerian Republic – officially opened Oran’s new main wastewater treatment plant.
Algeria’s largest wastewater treatment plant, second largest in Africa
Oran is currently Algeria’s largest wastewater treatment plant. It was planned and constructed by WABAG as consortium leader. DHW Oran, the wilaya’s water authority and the project’s client, invested more than €50 million in it. Of this, WABAG’s share came to over €30 million, encompassing planning, delivery, construction, commissioning of the complete mechanical engineering part and the subsequent operational management of the plant for two years.
With a capacity of over 300,000m³/day, the treatment plant handles a huge volume of wastewater. The plant’s integrated design combines a water line for biological wastewater treatment with stabilisation of the accumulating sewage sludge in the sludge line.
The plant’s main components include mechanical pre-treatment, biological treatment based on the well-proven activated sludge process and disinfecting as the third stage. The sewage sludge accumulated during the treatment process is concentrated in order to undergo a subsequent controlled digestion stage in bioreactors, before the stabilised sludge can be de-watered and disposed of in an environmentally sound way.
Here are some details of the plant’s dimensions: purification in four primary clarifiers with a diameter of 49m, a four-line activated sludge treatment stage with a total area of 90mx90m and a depth of 5.25m, and eight secondary clarifiers with a diameter of 56.6m. Stabilisation of the sewage sludge takes place in four bioreactors with a volume of 9,600m³ each.
The plant’s commissioning started several weeks ago by filling the tanks with wastewater from the municipal sewage network. By the time an appropriate amount of sludge becomes available from the biological treatment stage, the sludge line will have become operational too. The purified effluent is diverted into a saline lake, but it is planned to recycle it in the future for agricultural irrigation.
Praise from the top
President Bouteflika appeared to be very impressed by the large treatment plant and praised the project’s accomplishment. With the commissioning of the Oran wastewater treatment plant, WABAG continues a series of plant completions. During the current year, the company has already commissioned the wastewater treatment plants in Médéa, Baraki, Jijel and Reghaia.