Effect of cutter type on sediment pollutants release in channel dredging

Dredging activities are often used to maintain existing navigation channels. However, traditional dredging equipment inevitably leads to sediment resuspension and nutrient loading in water. In this work, the existing cutter used for dredging was transformed environmentally to reduce the release amount of sediment pollutants, and to avoid the formation of secondary pollution to water bodies. Simulated tests with a general cutter, a spiral cutter, along with a general and spiral cutter equipped with the anti-diffusion device were conducted respectively in this study. The change of pollutants concentration in overlying water was examined. The environmental performance of each different structure cutter was comparatively analysed as well. The result revealed that in channel dredging with a spiral cutter, the release amount of sediment pollutants was less than with a general cutter, and that a general/spiral cutter equipped with the anti-diffusion device could effectively reduce the release amount of sediment contaminants, particularly the release of the nitrogen nutrient during the 1h after the dredging treatment. The best transformation scheme for a cutter suction dredger (CSD) in its environmental-protection function may be: a spiral cutter equipped with the anti-diffusion device.