To evaluate the remediation performance of recycled oyster shell powders to control nutrients release from polluted sediments. Different types of recycled oyster shell powder were applied on separated bottom sediments. The first type of oyster shell powder is Calcined Oyster Shell Powder (COSP) and another consist of ultrasonicated oyster shell powder (SOSP) which were composed of calcium peroxide. The recycled oyster shell powders were improving the water quality as slow oxygen releasing compound. The experimental results indicated that the Dissolved Oxygen (DO) in the treated columns were higher than the control column. pH was increased in the both experimental columns due to the hydrolysis of CaO2. Meanwhile, recycled oyster shell powders could prevent the nutrients (nitrogen and phosphorus) release from sediments into the overlying water. In addition, the total nitrogen and total phosphorus concentrations of the COSP applied column were decreased 27% and 20% compared to the control column respectively and the SOSP applied column were decreased 33% and 27% compared to control in the overlying water. It was proved that, COSP and SOSP can effectively adsorb phosphorus from sediments and prevent phosphorus release into overlying water from bottom sediments. In conclusion, COSP and SOSP applications was increased DO in the overlying water and nutrient released controlled effectively from the sediment.

Abstract
1. Introduction
2. Materials and Methods
    2.1. Sample collection and study area
    2.2. Preparation of calcined and ultrasonicatedoyster shell powders (COSP and SOSP)
    2.3. Experimental incubation
    2.4. Analysis of physicochemical property andchemical analysis
3. Results and Discussion
    3.1. Changes of pH and DO in the overlying waterby adding oyster shell powder
    3.2. Effect of recycled oyster shell powder onnitrogen release in the overlying water
    3.3. Effect of recycled oyster shell powder onphosphorus release in the overlying water
4. Conclusion
Acknowledgments
REFERENCES

• Md Akhte Khirul(Department of Ocean System Engineering, College of Marine Science, Gyeongsang National University)
• Beom-Geun Kim(Department of Ocean System Engineering, College of Marine Science, Gyeongsang National University)
• Daechul Cho(Department of Energy and Environmental Engineering, Soonchunhyang University)
• Sung-Hyun Kwon(Department of Marine Environmental Engineering, College of Marine Science, Engineering Research Institute (ERI), Gyeongsang National University) Corresponding author