Treatment of Slaughterhouse Plant Wastewater by Sequential Chemical Coagulation-Continuous Flow Electrooxidation Process

Abstract

Wastewater from a small animal slaughterhouse (SWW) was treated by a two-step process: coagulation/flocculation (CF) followed by continuous flow electrooxidation (CFEO). Initially, a coagulant dose of 0.8 kg m−3 in the CF process, using FeCl3 at pH 8.5, achieved 52% COD and 63% turbidity removal (effluent: 2000 mg l−1 and 65.2 NTU). Alum, (optimum pH = 6.5), yielded 50% COD and 55% turbidity removal (effluent of 2100 mg l−1 and 78.5 NTU). Subsequently, when employing the CFEO process following the CF process with FeCl3, the study achieved highly efficient results. Specifically, under optimum conditions (residence time in the CFEO reactor, τ = 240 min, wastewater feed rate to the reactor = 15 ml min−1, and current density = 300 A m−2), the COD and turbidity removal efficiencies reached 99.60% (resulting in an effluent of 8 mg l−1) and 99.9% (resulting in an effluent of <0.10 NTU), respectively. In conclusion, the CF + CFEO consecutive treatment process demonstrated remarkable treatment efficiencies, with COD and turbidity removal rates of 99.9% and 99.9%, respectively. Moreover, the total operating cost of this treatment process was found to be 3.60 US $/m3.