Degradação eletroquímica e eletroquímica fotoassitida de efluentes lácteos

Abstract

The present study evaluated the efficiency of the electrochemical and photochemical electrochemical method for the degradation of effluent from the dairy industry, previously treated by biological processes, was evaluated using a commercial Ti/Ru0.3Ti0.7O2 anode. The effluent presented a significant amount of chloride ions (730 mg L-1), after conversion to free chlorine, thus generating, besides hydroxyl radicals, chlorine radicals which have high mineralization power. Thus, a complete factorial design 23 was performed, where the time, pH and current factors were assigned to verify the interaction of these variables during effluent degradation. The efficiency of the process was determined by analyzing COD as a dependent variable. After determining the ideal pH, the central composite design (CCD) was performed, where the optimal degradation conditions between the current factors (533.42 mA) and time (60.45 minutes) were determined. The effluent was submitted to electrochemical and photochemical electrochemical treatment at 15, 30, 60, 120 minutes in order to evaluate the behaviour of specific parameters such as COD, BOD5, TOC, colour, Turbidity, conductivity, pH, chlorides, COD/TOC ratio, COD/BOD5 and phytotoxicity. Photochemical electrochemical degradation was more efficient than electrochemical degradation. The photochemical electrochemical method promoted a marked reduction in the amount of chloride ions present in the effluent, indicating that the photoactivity provided the ions to the chlorine radicals, among other chlorine compounds, thus aiding in the mineralization. Hybrid degradation, photo-assisted electrochemistry, left all parameters within the standards set by legislation for disposal purposes, leaving the final product less toxic than the initial effluent, better biodegradability and relatively low cost of treatment (2.25 kWh m-3 effluent).