TECHNICAL ASSISTANCE, CONTROL AND MONITORING OF THE REHABILITATION AND EXTENSION WORKS OF THE MEDJAZ BAB WASTEWATER PLANT

Project components

The rehabilitation and extension of the treatment plant is designed to meet the treatment needs of the Medjaz Bab urban area until 2041. The process chosen is biological treatment by low-load activated sludge, in an oxidation basin followed by secondary decanters and sand filtration and UV disinfection. Sludge dehydration is ensured by a centrifuge. Nitrogen elimination is ensured by nitrification and denitrification. Phosphorus treatment by chemical precipitation is also planned, as well as odor treatment by bio-filtration.

The treatment process includes the following works:

• Wastewater pumping station by 3 Archimedes screws;
• Screening consisting of a mechanical screen;
• Sand removal and oil removal in a double aerated channel;
• 2 lines each comprising 3 basins equipped with surface aerators and submersible agitators;
• sedimentation in 2 rows of secondary decanters (4 basins) rectangular, equipped with suction scraping bridge;
• recirculation of sludge towards the start of the aeration basins;
• extraction of excess activated sludge towards the thickener;
• dosage with aluminium sulphate for the chemical precipitation of phosphorus;
• thickening in 1 square thickener, equipped with scraping bridge;
• dehydration of thickened sludge on 14 drying beds over an area of ​​8050 m2.

Scope of works

The services covered three main missions:

• Mission A: Technical assistance for the evaluation of offers
• Mission B: Control of studies and approval of execution plans
• Mission C: Control, monitoring and supervision of works and performance control