The invention provides a novel composition and method for removing or reducing levels of recalcitrant constituents from an effluent, such as lignin chromophores, AOX species, such as chlorinated phenols, dioxins, dibenzofurans, biphenyls, and high molecular weight material produced in the pulp and paper bleaching operations which includes using a composition comprised of (a) an amount of a source of an oxidant effective for oxidizing and thereby reducing the levels of such constituents and (b) an oxidatively stable oxidant activator having structure (I), wherein Y1, Y3 and Y4 each represent a bridging group having zero, one, two or three carbon containing nodes for substitution, and Y2 is a bridging group having at least one carbon containing node for substitution, each said node containing a C(R), C(R1)(R2), or a C(R)2 unit and each R substituent is the same or different from the remaining R substituents; M is a transition metal with oxidation states of I, II, III, IV, V, VI, VII or VIII or selected from Groups 3, 4, 5, 6, 7, 8, 9, 10 and 11 of the Periodic Table of the Elements; and Q is any counterion which would balance the charge of the compound on a stoichiometric basis.