I believe someone has already ...

I believe someone has already wisely suggested that you contact vendors.  There are a large number of media manufacturers and the volume of media you need will depend on the type of media you select and the effective surface area of the media.  Make sure the sizing is based on BOD loading and not simply sewage flow, and ask for references.  Contact the treatment plants referenced and ask for information on the BOD/COD and ammonia loading, effluent quality, flow rates, tank sizes, proportion of media by volume, aeration capacity and system used.  The literature contains a lot of unqualified information and summaries that can be highly misleading.