This blog post examines why marine pollution dredging cannot be limited to mere removal and disposal. It explores the necessity of circular technologies that transform polluted sediments into targets for purification and recycling, along with their environmental and industrial significance.
As marine pollution intensifies, the international community has established various norms and systems to protect the marine environment. A prime example is international treaties like the London Convention, which regulates the dumping of waste at sea. The conclusion of such treaties demonstrates a growing international consensus on marine environmental protection while simultaneously highlighting the practical challenge of how to clean up already polluted oceans. Particularly, contaminated sediments that have sunk and accumulated on the seabed over long periods exert a persistent detrimental impact on the entire marine ecosystem. Consequently, the need for marine cleanup technologies to remove and treat these sediments has become increasingly prominent.
The most widely used method for removing contaminants sunk on the seabed was dredging, a technique similar to vacuuming with a cleaner. While effective for directly scooping up and removing accumulated sediment from the seabed, this method caused significant problems after dredging. The process of separating pollutants from the dredged sediment and disposing of them produced foul-smelling gases. Furthermore, sediment laden with heavy metals remained around ports, posing a lethal threat to marine life. Consequently, severe environmental problems, such as mass fish deaths, repeatedly occurred in specific sea areas. These issues clearly demonstrated the limitation that simply removing the pollution source through primary methods cannot fundamentally solve marine environmental problems.
Against this backdrop, eco-friendly construction methods have recently been developed to address the shortcomings of conventional dredging and minimize environmental burden. This method differs significantly from conventional approaches in that it focuses not merely on dredging and disposing of contaminated sediments, but on recycling them into new resources. In essence, it represents an approach that seeks to transform marine cleanup from another cause of environmental destruction into an opportunity for resource circulation.
The eco-friendly dredging treatment process is carried out through several systematic stages. First, sediments dredged from the ocean are separated from foreign materials like gravel or debris. The separated sediments are then transferred to an electrolytic reactor for an electrolytic reaction. During this process, the strong oxidizing power generated at the anode and cathode effectively removes malodorous gases such as mercaptans and hydrogen sulfide. Simultaneously, organic matter contained in the sediments decomposes, significantly reducing their pollution level.
In the next stage, the introduced sludge is sent to a chemical reaction tank for flocculation and sedimentation. During this process, the sludge is dewatered via a centrifuge, and the dewatered sludge is transported separately. Meanwhile, the organic phosphorus components contained in the treated water undergo a removal process utilizing superconducting magnets. The separated and recovered phosphorus components are not simply discarded but can be recycled as a resource usable in agriculture or industry, offering a significant advantage.
The treated water emerging from this process undergoes further purification through a fine filtration stage before being discharged back into the sea. This structure substantially reduces the logistics costs required for transporting dredged material off-site and also lowers the overall cost of treating polluted sediments. This approach can be evaluated as a sustainable marine purification method not only from an environmental perspective but also from an economic standpoint.
So, how can the cake-like sludge remaining after separation through multiple processes be utilized? Since this sludge originates from natural mud, it can be recycled as a green environmental product through appropriate treatment. Dredged sediment solidified by mixing with solidifying agents can be used as backfill material. It can also be converted into eco-friendly materials that replace cement, reborn as various industrial products like bricks, blocks, and artificial reefs.
Its potential is also significant when used as household materials. This material can serve as a substitute for gypsum used in home interiors. Its natural properties also contribute to improving indoor environments. Furthermore, the presence of salt can help inhibit mold growth. Even if damaged over time, it can either decompose naturally or be recycled again, meaning there is virtually no limit to the number of times it can be utilized as a resource. South Korea, being a peninsula surrounded by sea on three sides, possesses the geographical advantage of being able to secure this resource stably.
As the limitations of finite resources and environmental pollution become increasingly critical worldwide, the demand for renewable energy and sustainable technologies is being emphasized more than ever. Within this era of change, technology that simultaneously cleans up marine pollution sediments and recycles them as resources is bound to receive significant social and environmental acclaim. Going forward, this technology is highly likely to be utilized across diverse industrial sectors, continuously developing and improving. Its value and role are expected to expand further as an alternative technology that simultaneously achieves marine environmental protection and resource circulation.
