The natural accumulation of soil particles washed by rainwater, their transporting and storing is a natural and inevitable phenomenon of the lake colmatation. Decreasing this process through protective strips is only partially successful [1]. The elucidation of the ways of exploiting sediments with the maximum yield in the process of the lake decolmatation is one of the basic purposes of this paper. The samples of underwater sediment from the right bank, thicket of the Ghidighici Lake have been taken. By stirring the water-sediment system and the separation in time of the suspension from the sedimented part along with periodically adding new quantities of distilled water, fractions of dispersion systems of different density and hydration have been obtained. In total, seven fractions have been separated, of which five minerals: heavy sand (1), semi heavy sandy (2), sandy-clayey (3), clayey (4), ultrafine (7) and two organic fractions; organic rough (5) and organic medium (6). The name of each fraction describes the general composition of the fraction. For example, the first separate fraction called “heavy sand” contains large sand granules and fragments of scallop shells. A separate case is the seventh fraction, the lightest one, in which the intensively hydrated fine minerals predominate. This fraction separates with great difficulty, the reason being the long duration of staying suspended. In order to facilitate the separation process of this fraction, it has been combined with a cationic surface agent (Ct SA), which forms combinations with ions from the particle structure. A series of combinations of the same amount of suspension (samples containing a constant sediment mass) were modeled in the laboratory, to which were added increasing volumes of 10-4 mol/L of N-cetylpyridine, the volume of each sample being equal. Concentrations of the series of samples were within the range of 2•10-6 - 60•10-6 mol/L of Ct SA. An obvious flocculation process occurred in samples with concentrations in the range of 16•10-6 - 48•10-6 mol/L, while in the sample with the concentration of 32•10-6 mol/L of N-cetylpyridine the flocculation was delayed. The fastest flocculation (in less than one minute) occurred in samples with a concentration of 24•10-6 and 40•10-6 mol/L of Ct SA. The braking effect of formation of floccules is most likely conditioned by particle restructuring and recombination of cationic ions with new anionic groups. For the samples treated with small amounts of Ct SA, a reference one, but also that of the closest to the beginning of flocculation process, the titrations showed a masking effect of the anionic groups. Therefore, N-cetylpyridine has also the role of masking the anionic groups of fine clay particles. The restructuring effect is repeated symmetrically at concentrations of about 32•10-6 mol/L of N-cetylpyridine. This is also confirmed by the NaOH titration of sedimented floccules, as the filling of the negative charges occurs at the gradual addition of Ct SA. On the other hand, the UV spectrum highlights the fact that, starting with concentrations of 32•10-6 mol/L of N-cetylpyridine, it is present in the solution samples in which flocculation has occurred. Therefore, other types of equilibrium with another ratio of cationic substance are required to supplement the groups still uncoupled with N-cetylpyridine, the concentration of which would be required to increase in solution. This fraction exhibits a good adsorption capacity of about 2.7 mmol/g of N-cetylpyridine.