Treatment of slaughterhouse wastewater

In this paper an evaluation of the effluent treatment plant of a slaughterhouse which processes 650 head of cattle a day is presented. Some problems in the operation of the anaerobic reactor and anaerobic lagoons caused by the presence of fats and suspended solids in the effluent were detected. A flotation system by pressurized air injection was tested at the plant. The fat removal efficiency obtained was 63% and 37% for red water and green water, respectively. In order to improve the hydrolysis of particulate matter, a system of two UASB reactors with recirculation, connected in series, was tested at laboratory scale. Removal efficiency was 77% for soluble COD and 82% for insoluble COD, at a volumetric load of 1.8 kgCOD/m³/d. Based on the results of these studies, several modifications in the treatment plant were proposed.