Avaliação da eletrocoagulação como tratamento de efluente proveniente de indústria de processamento de milho, com ênfase na remoção de fósforo

Abstract

One of the challenges of large industries is to maintain competitiveness, combining development and respect for environmental guidelines. Thus, the management of effluents in an environmentally correct and economically viable way has become important for research and investments in different industrial sectors. The application of electrocoagulation technology in effluents from the corn processing industry to remove phosphorus has been little explored in research só far, which justifies the importance of this work. This research aimed to investigate the treatment by electrocoagulation of wastewater from a corn processing industry. The experiments were carried out in a batch cylindrical reactor with six monopolar aluminum and iron electrodes, arranged in series and connected to a DC power source. 500 mL of raw effluent with an initial pH of 5,3 and secondary effluent with a pH of 7,3 was treated at room temperature and atmospheric pressure for 60 min. The effects of the potential (6, 9 and 12 V) and the addition of electrolytes (0,5 and 1,0 g / L) were explored in relation to the efficiency of phosphorus removal, turbidity and COD. Using aluminum electrodes for treatment with raw effluent, phosphorus removal reached 99,7%, while turbidity and COD reached 99,4% and 29,8%, respectively. With the use of iron electrodes for raw effluent, the removal of phosphorus, turbidity and COD reached 99,0%, 91,8% and 27,5%, respectively. For treatment with secondary effluent and aluminum electrodes, the removal of phosphorus, turbidity and COD reached 98,7%, 95,2% and 30,8%, respectively. Using iron electrodes, for secondary effluent, the removal for phosphorus, turbidity and COD reached 96,0%, 80,9% and 26,9%, respectively. The cost for operating the proposed system (using iron electrodes and a current density of 5.8 mA/cm²) reached a value of 0,43 R $ / m³, totaling the daily operating cost of R$ 2.607,85, equivalent to 6,6% of the total operating cost of the studied ETE. These results indicate that, under the studied operational conditions, the electrocoagulation of this specific effluent can be a viable alternative for the removal of phosphorus and turbidity as a tertiary treatment.