Aplicação das reações eletroquímicas e de fenton no tratamento de efluentes gerados por biodigestor alimentado com resíduos da suinocultura

Abstract

The advanced oxidative processes (POAs) are processes that consist of the generation of reagents with high oxidizing power, such as the hydroxyl radical (Eo = 2.80V), which are capable of oxidizing or mineralizing a wide variety of compounds, including refractory compounds to processes oxidation. These processes have been successfully applied in the treatment of water and effluents. Among the POAs, Fenton's reaction has been shown to be low toxicity and cost, and the reaction presents high efficiency for the mineralization of most organic compounds (H2O2 and Fe2+). A very promising technique is electrochemistry, because it is a simple and quite efficient technique. In this project, the Fenton reactions and / or electrochemistry were used in the treatment of liquid residue of the biodigestor used in the treatment of effluents generated in the rearing of pigs. For the first step, the Fenton reactions and their combinations with the filtration / adsorption processes were tested and the results show that only when the Fenton reaction is employed, a low efficiency is possibly observed due to the high amount of particulate material present in the reaction medium. The combined filtration and adsorption processes followed by the Fenton reaction showed a reduction of 83.24% and 92.21% in turbidity and COD, respectively. The second part of the work was to optimize experimental electrochemical reaction by evaluating the influence of experimental conditions (electrolyte and temperature) on the efficiency of the reaction. In this study a significant effect of Chloride in the reaction was observed, reaching a reduction of 80.46% of COD and 97.91% of turbidity. Despite the efficiency the system presented a high energy consumption 3 to 3,8 kW / m3. In the third step the associated electrochemical processes followed by Fenton were tested. In this study the efficiency was very close to the individual electrochemical system, but in this case with lower energy consumption. In addition, toxicity tests were performed on the effluent treated with lettuce seed (Lactuca sativa). The treated effluent presented higher toxicity than the initial effluent, possibly due to the electrogeneration of toxic species.