The work presented in this chapter deals with the retort water and represents part of a larger research project which deals with the development of kinetic data for aerobic biological treatment of the in situ shale oil retort wastewater. Specifically, this chapter deals with evaluation of two alternative pretreatment processes: chemical coagulation with sedimentation or flotation and chemical oxidation. The pretreatment goals were to achieve significant removal of suspended solids and chemical oxygen demand and to modify the waste characteristics to improve the biological treatability of the waste. Since ammonia removal is one of the prerequisites to biological waste treatment for retort waters, reductions in ammonia were monitored during this investigation.