Filtering mixed return and outdoor air

Hi Zenep, Yes, it is acceptable when it has high static pressure. Only then does the fresh air pass through the filter medium located in the duct.

Hello! Epigraph: brevity - the sister of talent, but not of mine talent. 
I suppose that you are talking about option 1 for mechanically ventilated spaces. In that case the only issue that I see - is from where the return air comes from.  Since it's a yarn factory, I suppose that supplied air in that amount is going to the main area where main working process occures and main place of staff circulation / working places.  I believe that such area is classified as "General manufacturing (excludes heavy industrial and processes using chemicals)" per Table 6-1 of ASHRAE 62.1-2010. Air in such areas is class 3 per the same table.  Since per p. 5.16.3.3.1 the recirculation of Class 3 air within the origin space is permitted, it's ok if:

• the all return air comes from the same main area (class 3), or area of class 2 air with the same or similar purpose or task and involve the same or similar pollutant sources (point 5.16.3.2.2 of AHRAE 62.1), or area of class 1 air without limitations, or mix of this airs;
• supply air from this huge industrial ventilation systems is going to the same "General manufacturing (excludes heavy industrial and processes using chemicals)" area and not supplies air to other areas that areas of air class 2 or 1, or class 3 but other space (since per 5.16.3.3.2 "Class 3 air shall not be recirculated or transferred to any other space"), per Table 6-1.

Otherwise I don't see limitations for mix air filtering. Just be sure that all requirements for the filtering media from maintenance point of view are also met.    I hope it helps. 

Looks fine to me.