an improved system and novel components and methods for treating waste waters contaminated with a variety of commercial , municipal , and / or industrial contaminants . a mixing vessel according to the invention comprises upper and lower mixing chambers connected by an intermediate tubular section and a fluid exit tube running coaxially down the center of the intermediate tubular portion . the fluid stream to be treated flows in a spiral pattern vertically through the vessel , providing turbulent flow . the flow stream may be subjected to electric or magnetic fields . in one embodiment , streams of the fluid to be treated and of an ionized coagulant are combined prior to entry into the vessel ; in another embodiment , the incoming flow stream is combined with the coagulants in the mixing vessel . the incoming flow may be split between annular passageways to improve mixing . magnetite particles may be generated in situ and added to the flow stream to further encourage coagulation in the presence of a magnetic field . after exiting the mixing chamber , the coagulated contaminants may be removed using a variety of filtration steps .