Abstract: An assembly and process for treating contaminated fluid. The assembly has a reactor including a tank with an internal weir, a low speed mechanical mixer, and means for delivering fluids to subsequent stages. A first stage has polymer make-up and coagulant feed units plus a dilution means which deliver modified contaminated fluid to a second stage with a low impact feed pump to preserve flocculant integrity. In a third stage, first sub-assemblies of self-cleaning magnetic shuttles capture at least some of the magnetic flocculant that escapes in the clarified effluent. In a fourth stage, second magnetic drum-type sub-assemblies separate magnetite particles from the flocculant, return the magnetite to the reactor, and send the non-magnetic solids to a fifth stage—dewatering. This stage has a receptor for accommodating solids that are optionally treated with a coagulant and flocculant to produce solids to be transported to a landfill.