굴 패각 소성재를 이용한 연안 오염 퇴적물의 간극수 거동 실험 연구

Abstract

In order to use oyster shells after a pyrolyzing to improve pore water quality, we developed the pretreatment conditions of oyster shells. And we applied it on coastal sediments to evaluate the behavior of pore water. First, pretreatment conditions of oyster shells for the removal of dissolved phosphate were determined to utilize the oyster shell as a material for the remediation of coastal sediments. Experimental results show that the oyster shell pyrolyzed at 600°C is about 5 times higher in phosphate removal than other pyrolysis temperatures. Oyster shells pyrolyzed for over 6 hours have higher efficiency on removal of phosphate than that of less pyrolyzing time. The smaller particle size shown the higher the efficiency on dissolved phosphate removal. Phosphate adsorption of oyster shell was suitable to be analyzed by Langmuir model and maximum adsorption amount was 12 mg/g. Through the XAFS analysis, we confirmed that the phosphate removal mechanism of pyrolyzed oyster shell was due to the formation of calcium phosphate. Changes in behaviors of pore water with pyrolyzed oyster shell(POS) were evaluated by mesocosm experiment. Experimental results show that the pH of experiment case increased up to 17% compared the control case. Ammonia concentration in overlying water of capping case was 9% lower than that of the control and 16% higher in the pore water. On the other hand, in the mixing of PS with sediment, the ammonia concentration decreased by ca. 8% both in overlying and pore water. Phosphate concentration in the capped and mixed cases decreased by 26% and 34%, respectively, in overlying water, and 28% and 36%, respectively, in pore water. The permeability coefficient of sediment with POS was 1.6×10-6 cm/sec. Transfection ability was increased by 3 times as compared with the control and SAR was decreased by ca. 15% compared with the control. Overall, it was confirmed that the pyrolyzed oyster shell is active material capable of removing dissolved phosphate in the form of calcium phosphate. For the result obtained above, pyrolyzed oyster shell is a materials for improving pore water quality of coastal sediments.