Electrocoagulation Technique for Treating Swine Slaughterhouse Wastewater from Batch to Semicontinuous Operation Mode

Abstract

In this study, industrial swine slaughterhouse wastewater was treated by electrocoagulation process using batch and semicontinuous operation systems. Electrochemical technique was carried out in batch operation mode during 2.5 h applying different current densities in sulfate and chloride media. After finding the best operating parameters in batch mode (lab-scale), the process was transferred to a semicontinuous pre-pilot scale process using a filter-press FM01-LC type electrochemical reactor fitted with flat plate aluminum electrodes. In this stage, distinct current densities and mean linear flow rates were assessed.Total organic carbon, chemical oxygen demand, total phosphorus, total nitrogen, and potassium among other parameters were analyzed during both treatments. The industrial swine slaughterhouse wastewater contained TOC 333 mg L–1, COD 1765 mg L–1, TP 13.55 mg L–1, TN 327 mg L–1, K 45 mg L–1, turbidity 102 NTU, color –absorbance 0.90 A.U. at 415 nm–, conductivity 1.9 mS cm–1, and pH 6.9. The highest TOC removal efficiency (72.7%), in semicontinuous process, was found at j = 25 mA cm-2 and ur = 0.64 cm s-1 with an energy consumption of 19.80 kW h m-3. Residual COD and TP concentrations met the international standard limits. Moreover, complete discoloration and disinfection were achieved. EDXRF, SEM, EDAX, XRD, and FTIR analyzes indicate pollutants were removed by adsorption on aluminum/iron hydroxides/oxyhydroxides.