Technology of improving water quality of sea area by use of steel slag products

JFE Holdings, Inc.

MarineBlock covered by marine bivalves

MarineRock covered by seaweed

Restoration of marine ecosystems using MarineStone

Outline

【JFE Steel Corporation】
The water quality of sea area in front of Yamashita Park is getting worse, the seabed is covered by mud, and problems such as red tide or poor oxygenation of water occur in summer season. To cope with them, JFE Steel is promoting a joint research project* with the City of Yokohama to confirm improvement methodology of marine environment by setting steel slag products on the coastal zone which is expected to have effects of organism clinging base and improvement of seabase.
*Joint research related to research on techniques to improve a marine life environment and facilitate the natural cleansing ability of seawater near the shores of Yamashita Park.

Description

In a joint research project* with the City of Yokohama, JFE Steel Corporation set steel slag products on the coastal zone of Yamashita Park and has studied for four and a half year of investigation. Consequent results were obtained as follows.
- Recovery of biodiversity by use of organism clinging base material Marine Block™ and Marine Rock™, and seabed improving material Marine Stone™.
- Improvement of water quality by promotion of filtration organic inhabitation.
- Inhabitation of various lives such as shellfish or fish.
- Ability of water purification was evaluated as 8500kL per day.
- Quantity of CO2 fixation during production of Marine Block™ was 280kg/m3.

Based on these results, JFE Steel Corporation has confirmed that steel slag products, including Marine Block™, which is steel slag absorbing CO2 gas, provide a highly effective base for nurturing and growing sea organisms while also facilitating the natural cleansing of seabed and seawater. We will continue to work on this project with the City of Yokohama toward improving the marine environment in Yokohama Bay and developing an attractive seaside town.

Marine Stone™, a gravel-type steel slag product, is a habitat forming material that suppresses hydrogen sulfide, which arises from an unhealthy seabed and improves water and sediment quality in enclosed coastal waters.

Its effectiveness in improving marine environments has been widely recognized, and the joint project with Hiroshima University received the Minister’s Prize (Ministry of Agriculture, Forestry and Fisheries) in the 12th Eco Products Awards and the Grand Prize in the 26th Nikkei Global Environmental Technology Award.
Hiroshima Prefecture has used a total of 38,000 tonnes of Marine Stone™ in its Fukuyama Port Marine Environment Creation Project (inner harbor area). Its marine environment improvement property was confirmed to still be effective in 2019, four years after its initial placement.

JFE Steel Corporation will promote development of blue carbon ecosystem deployment technology through above described slag products. For example, improvement of CO2 absorption quantity and strength at the same time is quite difficult by present technology. We will develop technology to obtain both high durability in the sea and increase in CO2 absorption quantity by controlling pore structure and mineral composition.