After having successfully carried out technical assistance since April 2017 to the National Sanitation Office for the construction in DBOT of the new Mahdia wastewater treatment plant (410,812 equivalent inhabitants), CONCEPT began in December 2021, the similar project of the extension of the Sud-Méliane wastewater treatment plant (746,250 equivalent inhabitants).

More recently, in April 2024, ONAS tasked a group with CONCEPT is a member of the assistance for the supervision of the extension works of the Sousse-Hamdoun wastewater treatment plant (32,000 m3/day). Another contract has just been signed with the same public body for identical services concerning the wastewater treatment plants of the cities of Béja (144,000 eq. inhab.) and Tabarka (45,000 eq. inhab.), services currently being started. The know-how capitalized by CONCEPT allows it to apply for wastewater treatment plants outside Tunisia, such as in Cape Verde where the Espargos plant on the tourist island of Sal has been received since June 2019 after complete project management by CONCEPT.