this is an oxidation - reduction treatment of wastewater with biomass , comprising a step of charging in the said system a recuperable oxidation - reduction mediator specie , a step of oxidizing terminal reducing agents with participation of the said recuperable oxidation - reduction mediator species , a step of reducing primary oxidizing agents with participation of the said recuperable oxidation - reduction mediator species , a step of retaining the said recuperable oxidation - reduction mediator specie in the treatment system in a form insoluble in the effluent , and wherein at least a portion of the said biomass together with the said recuperable oxidation - reduction mediator species are repeatedly treated in the said steps and . the metal containing species include iron , nickel , cobalt , manganese , vanadium , and combinations thereof . this method improves the removal of hydrocarbons , nutrients , toxic and recalcitrant organics , and reduces biomass generation .