Cleaning a rug is not as easy as it sounds, at least if the owner wants to treat it thoroughly. These pieces are soil gathering hotspots and can suck up several pounds of dirt and grime in a short time. If this soil is not removed promptly, it can damage the fibers, making it more difficult to salvage the rug. Regular treatment should be a primary goal, and it should be done with professional assistance.
Before a professional starts cleaning a rug, they have to inspect it for any damage. If there are no apparent problems, the first thing to do is to vacuum up any loose, dry soil from in between the fibers. After that, a technician will apply some water and a gentle agent, and then agitate it with a device that uses soft rotation. After thorough rinsing, the rug is extracted or spun in a centrifuge to extract most of the water. The rest of the drying process is handled on a rack. It will typically take several hours, and technicians will inspect it regularly during the process to look for any missed stains or other spots of damage. If no further issues are found, the rug will be returned to the owner once it dries.
Source from IICRC (Institute of Inspection Cleaning and Restoration Certification) website: http://www.iicrc.org/blog/cleaning-rug-104.html