Laboratory Study of Aeration as a Feasible Technique for Dewatering Fine-Grained Dredged Material

The purpose of this study was to examine analytically and experimentally the potential feasibility for employment of aeration as a means of hastening the drying of fine-grained dredged material. Laboratory experiments were conducted on two materials in which 3 - and 6 - ft cylindrical columns of slurry were aerated at various airflow rates employing various initial moisture contents from 200 to slightly over 300 percent. It was shown that bubbling of diffused air into the slurry increased the rate of the moisture loss. Statistical analysis of these data led to an empirical formula for predicting moisture content from initial moisture content, depth, and unit airflow rate for the two materials. The equation provided reasonable predictions for results obtained in another laboratory-scale slurry pit. Costs for using diffused air to enhance drying under field conditions will be rather high but may be warranted depending on the cost of purchasing and developing new sites. It was concluded that the process showed sufficient potential to recommend that field demonstration and design criteria studies be undertaken.