Removal of organic matter contained in slaughterhouse wastewater using a combination of anaerobic digestion and solar photoelectro-Fenton processes

Here, the mineralization of organic matter present in slaughterhouse wastewater from a Chilean meat company was achieved by a combination of anaerobic digestion followed by the solar photoelectro-Fenton (SPEF) process. The first step was the biological treatment, during which 90% of COD removal was achieved, producing 90 mL of CH4. Further, the post-biological effluent showed lower color, odor, amount of solids and turbidity but higher conductivity due to an increase in the concentration of NH4+ and NO3. This was followed by different electrochemical advanced oxidation processes (EAOPs): electro-oxidation (EO), electro-Fenton (EF) and SPEF. With SPEF, almost complete mineralization was achieved with a high efficiency. With SPEF, the fast mineralization rate is due to hydroxyl radicals ((OH)-O-center dot) that are generated in the bulk, on the anode surface, by solar radiation, and most importantly, by the direct photolysis of complexes formed between Fe3+ and some organic intermediates. The combination of both processes, biological digestion and SPEF, produces a totally clarified effluent, with a COD removal greater than the separate processes and better than the final effluent from industrial wastewater plants at comparable reaction times. (C) 2016 Elsevier Ltd. All rights reserved.