Ozonated liquid is mixed within a multi-stage clarifier system with wastewater to be treated and suspended solids are removed. The clarified effluent is filtered and exposed to ultraviolet radiation. Ozone is injected into the irradiated effluent and received within a contact tower where reaction between the contaminants and ozone takes place. The ultraviolet irradiated, ozonated, and clarified liquid is recirculated through an ozone injector and discharged through a mixer plate into a purge chamber. The purge chamber effluent is split, with a portion returning to the contact tower and passing through a second ultraviolet radiation source, and the remaining purge chamber effluent being distributed within the clarifiers. After a predetermined residence within the system, a diverter valve in the return line is operable to discharge the treated water through a carbon filter and out of the system. The recirculation of the UV irradiated ozonated liquid provides both effective solids removal and reaction of the contaminants with the ozone to produce an acceptable treated water.