The Effect of Flocculants and Water Content on the Separation of Water from Dredged Sediment

Abstract

Dredged sediment has high water content, and its engineering characteristics are poor; therefore, the treatment and disposal of dredged sediment is difficult, and the utilization efficiency of these resources is low. Various methods can be used to dehydrate dredged sediment, among which flocculation dewatering is the most widely used. In this study, the basic properties of dredged sediment were examined, and the flocculation dehydration effect of dredged sediment was analyzed in relation to the polyaluminum ferric chloride (PAFC) dosage, water content, and time. There is an optimal flocculant dosage added during dredged sediment processing. Dredged sediment with high water content has obvious flocculation effect. Flocculant can speed up the flocculation dehydration of dredged sediment in a short time, but long-term dehydration has no advantages compared with natural dredged sediment; the dehydration effect was even weaker than that of natural dredged sediment dehydration in the later stages of sedimentation. Meanwhile, this paper divided the settling process into different stages; the settlement coefficients and compaction settlement indexes in different settling stages can well reflect the flocculating performance of flocculants at each settling stage.