摘要:An investigation was made of various treatment methods for wastewater from the dredged soil disposal site of Osaka North Port Solid Waste Disposal Site. First, in an experiment using chemical precipitation by ferric chloride and polyferric sulfate, it was found that the COD value of 24mg/L of untreated wastewater fell to 8mg/L. But it was estimated the maintenance cost would be from 50 million to 400 million yen per year, so this method was discounted as too expensive. An experiment using highmolecular precipitants had little effect on wastewater with phytoplankton growth and muddy wastewater. The active carbon method was, of course, higly effective as a treatment method, but the cost of chemicals made it too expensive to be used, as was easily estimated. The microstrainer method was not effecttive and more investigation is necessary to reduce phytoplankton via the mesh of screen. The artificial fiber filter was effective, but the cost of construction and maintenance of the filter would not be economic. The natural sedimentation experiment, a fair part of suspended solid in muddy wastewater sedimented giving clean water within one hour. This method is already used to effect in the solid reduction membrane.