This month, CONCEPT completed the first phase of the rehabilitation study project for the Choutrana I wastewater treatment plant, the largest wastewater treatment plant in Tunisia. Designed for a capacity of 1,000,000 (population equivalent), this plant operates using an activated sludge process at medium load with anaerobic digestion of sludge and electricity production by cogeneration.

Launched in March 2025 on behalf of theONAS (National Sanitation Office) and under funding KFW, this project aims to sustainably improve the performance of the WWTP. The initial phase, now completed, aimed to establish a comprehensive diagnosis to prepare for future technical and environmental studies (APS, APD, EIES, hazard study). This diagnosis included the following assessments:

• Diagnosis of civil engineering structures.
• Control of electromechanical and automated equipment – Verification of the condition of the installations.
• Energy audit – Optimizing consumption for a greener WWTP.
• Operational modeling of wastewater and sludge treatment processes
• Evaluation and simulation of current performance
• Assessment of HSE conditions – Guarantee of a construction site that complies with standards.
• Preliminary study of rehabilitation variants – Comparison of possible technical solutions.

This phase ended with a restitution workshop organized on July 15 and 16, 2025 during which CONCEPT and its partners presented the results of this in-depth evaluation of the current state of the STEP.

The next stage, with the imminent start of the APS phase, will focus on the in-depth technical and environmental studies, in line with ONAS's support towards a sustainable and efficient rehabilitation of the station.

This project is part of an approach to optimizing sanitation infrastructure in Tunisia, with the aim of more efficient and ecological management of wastewater.

Stay informed about the progress of this strategic project for Tunisian sanitation!