MEASUREMENT OF THE INFLUENCE OF SALINITY ON FLOC DENSITY AND STRENGTH

The effective density and the strength of flocs formed in the laboratory from mud from the Tamar Estuary reached a maximum value at a salinity of 10-15 parts per thousand within the concentration range studied (0.1-1.0 g liter-1). For a constant salinity and concentration, the density decreases with increasing floc size. The strength of the flocs increases with the floc diameter. However, the strength of the individual particle bonds within the floc decreases with size. Large flocs were relatively more brittle than smaller ones. The results suggest that larger flocs may be disrupted by the formation of unequal fragments.