Enhanced dewater efficiency for river sediment by top-to-bottom water transmitting channels with different materials.

Abstract

Artificial top-to-bottom water transmitting channels made of threads of wool blend (WT), cotton (CT), flax (FT), and polyethylene (PET) were used to enhance the dewater efficiency for river sediment. In addition, the disordered channels composed of 3-mm-long WT segments mixed randomly into the river sediment were also employed. The most effective dewatering channels were found to be top-to-bottom WT channels with water absorption capacity of 8.7 ± 0.5 g · g-1 and volume compressibility of 2.94 ± 0.11. On the application of 0.1 MPa pressure to the mud surface, with initial water content of 60.0 ± 0.2 wt%, the water content obtained with channel material weight 0.411 wt% dry solids and channel to a mud cake height ratio of 0.95 upon 90-min dewatering was 39.6 ± 0.7 wt% with enhanced dewaterability, compared to that without channel addition, of 74.9 ± 0.9 kg · kg-1 · h-1. Using the same parameters, enhanced dewaterability was only 69.1 ± 0.3, 55.2 ± 2.8, and 9.1 ± 0.9 kg · kg-1 · h-1 for CT, FT, and PET channels, respectively. Moreover, the final water content of the mud cake dewatered in the presence of disordered WT channels at dosage 1.10 wt% was 49.8 ± 0.7 wt% with enhanced dewaterability of 5.9 ± 0.5 kg · kg-1 · h-1 only. These demonstrate that the compressibility of the water transmitting material is the main factor affecting dewatering efficiency with the water absorption capacity also being important.