I completely agree that your ...

I completely agree that your success lies upstream in the primary treatment.  This dictates how much of the nasty toxic or recalcitrant materials is in the influent to the biomass section.  You need to have a full water analysis of what you are treating.  There a lot of very experienced and knowledgeable people on this site that can provide you with some great advice, but you are putting the cart before the horse.  Once you have the water quality, we can all dream up at least a couple of designs, and then tell you why we would choose one or two over the others.  There are always risks associated with design, especially working off limited data.  There are a number of designs out there, so understanding what you are treating is essential, as well as mitigating any potential future challenges, so you can build in some fail-safe measures.  First concentrate on what can be mechanically taken out prior to the biology (O/G, Solids, Suspensions, toxic and recalcitrant compounds may or may not be taken out depending on how well you design the pretreatment (Primary Clarification), so that the bacteria can acclimate.  Also, you need EQ tanks to be able to control both the organic and hydraulic loading; maintain steady flow with a minimum disturbance to how much and what is being fed to the biology.  Looking forward to seeing what you come up with, so we have design parameters.  Also, very important, is your effluent guidelines.  This will dictate whether you need tertiary treatment for discharge or a potential recycle opportunity to ensure good stewardship and get EPA points for design being BAT at that time.  Best, Sean L. Roop - Senior Water and Wastewater Treatment Consultant - Industrial and Engineering Consultants, LLC