An apparatus and method for on-site treatment and reclamation of oil and gas well waste water or fracturing fluids. The mobile treatment process and apparatus provide both chemical precipitation and filtration to treat the drilling fluid waste to a technically and environmentally acceptable level allowing for reuse. Alkaline treating agents are applied to the drilling waste fluids, as they are pumped through the treatment apparatus, to increase the pH of the fluid waste to a preferred pH range and to also cause selective soluble contaminants in the fluids to form a precipitate. The waste fluid is allowed to clarify as the precipitate of insoluble contaminants, through flocculation, settle and form a sludge at the bottom of the drilling pit. The clarified fluids are then filtered to satisfy applicable industry and environmental requirements.