Abstract: Method of decomposing high molecular weight polymer downhole to prevent chelation of iron by residual high molecular weight polymer thereby producing flowback without iron contamination as chelated iron. A secondary method is also described to treat iron chelated produced water with oxidants at surface conditions, utilizing aluminum electrolytes, specifically low basicity polyaluminum chloride, to either co-precipitate residual polymer and bound iron, or to substitute chelated iron with aluminum in the polymer-metal complex, resulting in liberating of iron to enable neutral pH oxidation and removal by precipitation, coagulation, flocculation and physical separation. The produced water with removed iron can be then stored or re-used for other oilfield applications.