Correlation between dewatering index and dewatering performance of three mechanical dewatering devices

Abstract

Efficient sludge conditioning can improve sludge dewatering characteristics and promote the separation of flocs from the liquid phase to achieve a high solid content. To optimize this process, a reliable dewatering index must be established. Although numerous researches investigated sludge conditioning, few are devoted to the correlation between the conditioning index and the dewatering efficiency. In this study, sludges were conditioned with both synthetic and natural polymers, and their dewatering characteristics after three different mechanical dewatering devices, the filter press, belt press, and the centrifuge, were compared. The result shows that the traditionally used dewatering index may not reflect sludge conditioning properly. Correlation between sludge conditioning indices and dewaterability depends upon both the type of sludge and the means of sludge conditioning and dewatering. It is therefore concluded that dewatering index must be properly chosen for optimum sludge conditioning.