Particle dynamics of sewage sludge dumping in the ocean

The objectives of the study were to determine the rate of coagulation, the change in size distribution with time, and the equilibrium size distribution at different particle concentrations and turbulence. At a fixed mixing rate the initial coagulation rate is highest for the particle concentration of 1/50 dilution, steadily decreasing to 1/10,000. The time to reach an equilibrium size distribution is shortest for the 1/50 dilution and longest for the 1/10,000 dilution. The equilibrium size distribution series for 1/50 through 1/10,000 dilution will be presented. These experiments were conducted at up to four mixing rates in order to determine the effect of mixing on the parameters. A blade mixer and a Couette (double cylinder) mixer were used to determine the effect of different turbulent conditions. The settling velocity of flocs in sea water showed a wide range. The largest flocs had velocities of up to 0.4 cm/sec., but the smallest flocs had very slow settling velocities.