The performance of a continuously operated flocculent sludge UASB reactor with slaughterhouse wastewater

Abstract This investigation was carried out to assess the performance of a one-stage flocculent sludge UASB reactor treating slaughterhouse wastewater. The experiments deal with a continuously operated reactor at a process temperature of 30°C. The results of the present investigation indicate that the type of substrate ingredients, coarse Suspended Solids, colloidal and soluble compounds in the wastewater, affect the performance of the reactor because of different mechanisms involved in the removal of these substrate components and their subsequent conversion into methane. Two different mechanisms are distinguished in the removal of materials from the wastewater: the entrapment mechanism and the adsorption mechanism. The entrapment mechanism prevails for the elimination of coarse Suspended Solids while the adsorption mechanism is involved in the removal of the colloidal and soluble fractions of the wastewater. The results obtained lead to the conclusion that the system can satisfactorily handle organic space loads up to 5 kg COD m −3 day −1 at 30°C. The data indicate, however, that continuing heavy accumulation of substrate components in the reactor is detrimental to the stability of the anaerobic treatment process as the accumulation can lead to sludge flotation and consequently to a complete loss of the active biomass from the reactor.