Flocculation and sedimentation of fresh water dredged materi1l slurries.

Northwestern As a consequence of current environmental and economic constraints on the disposal of bottom sediments dredged from deep water harbours and channels, these materials are often placed in slurry form within on-land or off-shore dyked containment areas. Motivated by a need to accelerate sedimentation rates and minimize the amounts of suspended solids and other pollutants in the effluent water from these disposal sites, this study was conducted to evaluate the flocculation effectiveness of twenty-two different chemical additives on five typical dredged material slurries from four Great Lakes harbours. Although several promising additives have been identified, the effectiveness of any given additive was found to depend strongly on the physical and chemical nature of the dredged material slurry under consideration, and it appears that an appropriate additive for a given situation can be selected only on the basis of a custom-designed test program. (A)