Heterogeneous Fenton-type treatment of an industrial effluent from forest biomass processing

MASSA, PAOLA; FELISSIA, FERNANDO; FENOGLIO, ROSA; AREA, MARÍA CRISTINA; COVINICH, LAURA

Praga

Conferencia; 5th European Conference on Environmental Applications of Advanced Oxidation Processes ? EAAOP5; 2017

University of Chemistry and Technology

Alkaline sulfite treatment of wood in chemimechanical pulping do not have a chemical recovery system, and diluted spent liquors are generally treated in the effluent system. However, several of its components are refractory to typical microbiological degradation (i.e. aromatic derivatives from wood extractives and labile lignin fractions) and require more suitable technologies. Advanced Oxidation Processes (AOP) have emerged as promisory treatment alternatives. So far, among non-irradiated AOPs studies of industrial streams, those using Fenton type oxidation are scarce and kinetic information is very limited. Therefore the aim of this work was to propose a kinetic model for the degradation of mixed recalcitrant compounds from real wastewaters by copper based Fenton-type oxidation. Three mechanisms were studied for TOC reduction in alkaline spent liquors: heterogeneous and homogeneous oxidations, and adsorption of organic matter on the heterogeneous catalyst. A two step kinetic model was applied to TOC reduction in heterogeneous and homogeneous oxidations, admitting two sequential steps of oxidation a first fast stage followed by a slow one. The heterogeneous process was evaluated by examining temperature and catalyst load. Temperature affected dramatically the reaction and the kinetics constant increased linearly with the increase of catalyst load. TOC conversions and reaction rates of homogeneous oxidations were higher than those observed for the heterogeneous reactions. Adsorption of organic compounds onto CuO/γ-Al2O3 is mainly of physical nature. The simulated effluent from alkaline treatment of wood behaves as an anionic stream, with an easy adsorption to the active sites of alumina surface at lower pH.