Treatment by electrocoagulation process of slaughterhouse wastewaters

In this thesis, treatment of the wastewater obtained from the slaughterhouse in Tunceli province was investigated in a reactor which was formed in laboratory conditions by electrocoagulation process. In the process; the effect of different parameters such as current density, pH, distance between electrodes and operation time on treatment efficiency was investigated based on chemical oxygen demand (COD) and total organic carbon (TOC) removal. COD removal was investigated with classical optimization and the effects of the parameters on the process were determined. The highest COD removal (90.63%) was obtained at pH 7.47, current density 15 mA/m2, distance between electrodes 16 mm and operating time 60 minutes. In this conditions after treatment, removal yields of the oil and grease, total solids (TKM), volatile solids (UKM), ammonia nitrogen (NH3-N), nitrate nitrogen (NO3--N), nitrite nitrogen (NO3--N), total kjeldahl nitrogen (TKN), orthophosphate (PO4-3), turbidity and color was found as 92.22%, 42.94%, 75.38%, 51.37%, 71.69%, 77.18%, 79.64%, 96.84%, 99.81%, 98.41%, repectively. The values of operating cost and consumed amount of electrode were obtained as 9.15 TL/kg COD and 0.79 kg/kg COD and energy consumption was found to be 0.08 kWh/kg COD in optimum conditions. The TOC removal was investigated using central composite design under response surface method (RSM) and interaction effects of parameters on the process were determined. A second order model was developed by using variance analysis (ANOVA) and central composite design. Independent process variables values which give maximum TOC removal (94.77%) has been obtained as current density 22.97 mA/m2, distance between electrodes 12.03 mm and operating time 78.95 minutes. In optimum conditions after the treatment,removal efficiencies of the oil and grease, COD, TSS, VSS, NH3-N, NO3--N, NO3--N, TKN, PO4-3, turbidity and color has been obtained as 91.86%, 84.55%, 66.05%, 87.18%, 68.97%, 61.17%, 78.37%, 95.58%, 98.55%, 98.41%, respectively. The values of operating cost and consumed amount of electrode were obtained as 24.40 TL/kg TOC and 2.11 kg/kg TOC and the energy consumption was found to be 0.03 kWh/kg TOC in optimum conditions. These results confirm that electrocoagulation is an effective method for the treatment of slaughterhouse wastewaters.