Testing an artificial beach system for removal of pollution in a coastal zone

The developmental activities and utilizations of Japanese coastal seas have been increased recently. Consequently, the production of coastal fisheries, especially of those in enclosed seas, are considerably affected by artificial impacts such as reclamation from the sea and increased pollution load. The objective of this paper is to propose a new ecotechnological method to recover the polluted coastal environment by using an artificial beach system. An artificial beach (5 m × 10 m) was constructed in the Matsushima Bay facing the Pacific Sea, about 300 km northeast from Tokyo. The area was polluted by fishery production and untreated wastewaters from rural district. The major merits of this system are simplicity of the structure, energy-free operation, capability to use tidal current cycle effectively, and ease of maintenance. The results of field investigation indicated that rapid removals of turbidity, suspended solids, phosphorus and ammonium nitrogen by the artificial beach system were achieved. The removal rate of total organic carbon was high because of the retention of the particulate matters. These performances were related to physical and biological filtration through the artificial beach system. It suggests that restoration of polluted coastal area may be expected using this artificial beach system.