抄録
The natural features of estuaries and coastal areas are often seriously damaged due to the discharge of pollutants by human activities, and most natural seashores have disappeared and been replaced by man-made concrete blocks. However, it is a well-known fact that natural seashores have a high self-purification capacity.
The purpose of this study is to develop a new ecotechnologic method to restore the polluted coastal environment by using the artificial beach. The pilot plant of the artificial beach was constructed in the Shiogama Bay, facing the Pacific Ocean. The main merits of this system are a simple structure, free of energy demand, since the tide was used effectively, and purification is carried out by physical and biological filtration through the beach.
The results showed that turbidity was removed effectively and DO was consumed by biological degradation of particulate organic matter and nitrification ; all of these performances depended on both the movement of water and the addition of oxygen caused by the tide ; both were determined by the structure of the beach, which included scale, slope and kind of gravel. The effects of the sectional shape of the beach on the performance are discussed with respect to the results of a numerical simulation.
