Changes in Permeability and Benthic Environment of Coastal Sediment based on Calcium Salt Supplier

Abstract

Kim, K.M., Suh, Y.C., Lee, I.C., Choi, C.G. and Kim, K.H., 2019. Changes in permeability and benthic environment of coastal sediment based on calcium salt supplier. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 311-315. Coconut Creek (Florida), ISSN 0749-0208.This study aims at the remediation of anaerobic coastal sediment using a calcium supplying material. For the calcium supplying material, granulated coal ash (GCA) was developed using coal fly ash. We hypothesized that calcium ions supplied from GCA can improve the water flow conditions such as the shear frictional force or pore plugging. A change in turbidity of the clay suspension in varying ionic solutions confirmed that sodium ions from coastal sediment disperse the clay particles, whereas calcium ions released from GCA aggregate the clay particles following the electrical double layer theory. These electrical phenomena affect the change in permeability of a cohesive sediment, and GCA increases the permeability coefficient of the cohesive sediment by 3.5 times compared to the control case. According to the results of the sediment incubation experiment, the calcium concentration in the pore water statistically increased (p<0.05), whereas the sodium concentration statistically decreased (p<0.05), resulting in favorable conditions for pore water flows. The ORP increased from -25.9 to 46.9 mV by the activated pore water flows, resulting in aerobic conditions. From these results, we concluded that GCA, a calcium supplier, generates pore water flows, remediating anaerobic cohesive sediment.