Not all polypropylene is "chlorine bleach resistant" It began in the commercial carpets sector, made for the residential homes market but is now more widely available as a mass market product.
Polypropylene does however have a great resistance to most oxidising agents.
Talk to the technical dept at prochem on making a oxibrite - fibre buff - fibre shampoo solution as it is difficult to go wrong with the solution at the recommended dilutions. I f you want to experiment with it further then get some soiled carpet samples and have a practice at what can be achieved at different dilution rates.
If you want to discuss any further you can contact me via my website..
Peter
www.carpetcleanercardiff.com