Abstract
The solubilization of EPS (extracellular polymeric substances) in the activated sludge was introduced as a useful method to improve the dewaterability and fluidity of sludge. The EPS in the waste sludge floc matrix were partially solubilized by using acid or alkaline solutions. The solubilization of EPS remarkably improved the total solid and fluidity of thickened sludge after centrifugation. Moreover, the addition of 1 vol% dissolved EPS solution to the waste sludge was found to function similarly to commercial flocculant in aggregating solid particles under the gravitational field. These results demonstrate that the dissolved EPS can act as a bioflocculant. Furthermore, the phosphorus in the centrate of waste sludge can be effectively recovered using seawater as a precipitant and seed material. We proposed a conceptual flow sheet for the new treatment of waste sludge, in which the unit operation of EPS solubilization is introduced in the conventional sludge treatment and the dissolved EPS is recycled as a flocculant into waste sludge.
