Activated sludge treatment of abattoir wastewater—I: Influence of sludge age and feeding pattern

Abstract

As part of a study to provide data for the design of abattoir activated sludge plants laboratory-scale completely mixed reactors were fed with abattoir wastewater, continuously and intermittently using an 8 h feed, 16 h starvation pattern. The standard biokinetic coefficients and the effluent concentrations of COD. TKN and phosphorus were measured for the continuously fed reactors at sludge ages of 5, 10 and 20 days. Sludge settleability and filterability were also measured. Values obtained for the biokinetic coefficients Y and k d were within the range of values reported for other substrates but k was lower and k x higher. Effluent TKN and phosphorus concentrations were low at the three sludge ages, but the COD concentration was high at sludge ages of 5 and 10 days. In contrast to the data reported for many other wastewaters the effect of sludge age on the SVI was small. Intermittent feeding was tested at a single sludge age of 10 days. It produced an effluent and sludge with better and more stable characteristics than those from the continuously fed reactor at the same sludge age.