Routes & Main Controller / Specific Controller

Hello Fantastic CI community ! 

I'm actually stuck in my mind and i need your help if you have 5 minutes to give away in order to save my soul 

I need a route like that : 


But before to load a controller, i need to know which one and for that i need to check the info in the database regarding the ID i got (= (:num)). 
Cause i have a main table to list all the pages of the projects (around 100.000 pages) and in this main table, it's specified the related content table for each one. 

So first my idea was to do :


The Pages Controller is loaded and i can get all the informations, but after i don't know how to move to the specific controller (for example the Recipes Controller) cause there is no $this->load->controller() or something like that.

After, i had the idea to use a callback function in the routes file, to define the specific controller i need to load it directly. But it seems the callback function can not be used this way...

So i'm stuck

Please save me !
Thanks a lot !