Removal of Recalcitrant Organic Compounds From an Industrial Complex Effluent by Heterogeneous Fenton‐Type Treatment

Abstract

Because of their chemical complexity, industrial chemi-mechanical pulping effluents are evaporated and burned, in spite of the high associated cost involved in these processes. The aim of this study was to remove recalcitrant compounds from this kind of wastewater using a Fenton-type treatment. The main parameters involved in the process and their influence on the results were determined. Homemade catalysts based on CuO, Fe 2 O 3 , NiO, and ZnO, supported on g-Al 2 O 3 have been tested for catalytic oxidation, and the CuO/g-Al 2 O 3 catalysts showed the greatest effect on total organic carbon (TOC) reduction (52.7%). A series of two-level factorial experiments was subsequently applied to evaluate the most favorable range of conditions for CuO/g-Al 2 O 3 application. The studied variables were hydrogen peroxide concentration ([H 2 O 2 ], g/L), active phase content (metal oxide supported on alumina,%), mass of catalyst (metal oxide/alumina system, g), and reaction temperature (°C). The highest reduction of all parameters was obtained at the superior level of all variables with CuO/g-Al 2 O 3 , achieving reductions of chemical oxygen demand (COD) and TOC between 40 and 50%. Increasing catalyst mass did not produce additional benefit. This variable has a significant effect only on the reduction of aromatic compounds. At its low level, reduction in aromatic content exceeded 80%. Color reduction was influenced only by temperature (maximum reduction of 90%).

Kinetic modeling of a heterogeneous Fenton-type oxidative treatment of complex industrial effluent

“…Catalyst mass and active phase content were analyzed in a previous work through an experimental design, to find their impact on TOC and COD reductions. Between the two tested points, the catalyst mass did not have a significant effect on TOC and COD reduction, and the higher active phase tested showed better performance in oxidation trials [32], then, 0.5 g/L of 2.5% CuO/γ-Al 2 O 3 were used. The identified species in the chemimechanical black liquor (such as acetic acid, oxalic acid, sulfur compounds, sodium carbonate and other salts) [4], [5] are recalcitrant and interfere the Fenton oxidation process [33], avoiding a total mineralization [34], [35].…”