A system that includes a fuel treatment system. The fuel treatment system includes a hydrodynamic cavitation reactor that receives a fluid that includes fuel from a fuel supply and water from a water supply. The hydrodynamic cavitation reactor cavitates the fluid. Cavitation of the fluid cracks the fuel and forms radicals that combine with one or more substances in the fuel. A separator receives the fluid and separates the fluid into water, fuel, and one or more substances.