The process wastewaters from oil shale retorting originate from mineral dehydration, combustion, and input steam during pyrolysis of the embedded polymeric kerogen, a high-molecular-weight heterogeneous polymer. High concentrations of numerous organic and inorganic solutes are typically present. Although many of these compounds have been identified for a few waters. Most have not. For the waters the waters that have been studied only small portions of the spectrum of organic solutes have been found to be biodegradable during aerobic biological treatment. Insufficient acclimated biomass, low individual substrate concentrations, and chemical inhibition have been proposed as mechanisms responsible for the resistance of dissolved organic carbon presented in a range of process wastewaters. All of these purposed limitations could potentially be overcome by fixed biofilm treatment, which has inherent advantages over homogeneous disperse growth systems.