The present invention relates to novel methods for preparing fibrous catalysts, to fibrous catalysts, to catalysts systems and to uses of the fibrous catalysts in the treatment of a waste stream. The method comprising the steps of: (i) treating a fabric comprising polyacrylonitrile fibers with a hydrazine salt and a hydroxylamine salt in the presence of a base to provide a modified fabric; (ii) treating the modified fabric with a base; and (iii) treating the modified fabric with an aqueous solution comprising a salt of a transition metal cation and a salt of a non-transition metal cation. The transition metal cation is selected from a scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel and copper cation, and mixtures thereof; the non-transition metal cation is selected from a calcium, magnesium, lithium and zinc cation, and mixtures thereof.