Pukyong National University

Development of a technology to restore the coastal environment using oyster shells
PKNU completed empirical research on the improvement of sediment through oyster shell powder preprocessing

△ Photos before (on the left) and after spreading oyster shell powder (left) and after.

Research results show that it is possible to restore the coastal environment by recycling oyster shells, which are trouble on the coast of Gyeongnam, and are drawing attention.

Yeongnam Sea Grant Center (Lee Seok-mo, Director) of Pukyong National University announced on the 1, December that it has completed a demonstration experiment for improvement of the sediment, which is a recent research project, ‘Development of coastal ecological space restoration technology using oyster shells (Responsible Professors, Lee, In-cheol and Kim Kyung-hoi from Dept. of Ocean Engineering).’

Oysters grown mainly in the Gyeongnam region are actively consumed, such as being exported overseas, but nearly half of the 300,000 tons of oyster shells generated annually are not treated and are piled on the coast, causing problems such as marine water pollution and damage to the landscape. For this reason, billions of won are spent annually on oyster shell treatment.

In this research project, in order to fundamentally solve the problem of oyster shells, the center has developed a technology that reduces the cost of recycling oyster shells and utilizes them for coastal ecological restoration. The technology developed this time is to reduce the cost of recycling treatment by applying a heat treatment method at a relatively low temperature of 700 degrees, rather than chemically treating the oyster shell.

Since last June, the center has conducted monitoring of water quality, sediment, and benthic organisms for 5 months after covering a 10 cm thick heat-treated oyster shells on the top of contaminated sediments in a 100 ㎡ area near the oyster farm in Tongyeong, Gyeongnam.

As a result of the experiment, the concentration of phosphate in seawater (pore water) and upper seawater of the sediment decreased by  40% approximately. Especially, a decrease in anaerobe and a significant increase in the biomass of benthic organisms in the sediment were observed.

Professor Kim Kyung-hoi of Ocean Engineering said, "It is expected that oyster shells can significantly reduce the concentration of phosphate, a substance that has a great influence on the expansion of the red tide, not only to reduce damage from red tide, but also to restore benthic ecosystems, increase fishery resources, and increase the income of fishermen."

Since 2017, the center has been conducting research projects with the support of the Korean Institute of Marine Science & Technology Promotion (KIMST) under the Ministry of Oceans and Fisheries (MOF) and obtained these findings through a verification experiment this year. <Pukyong Today>


△ A shoot of people spreading oyster shell powder.