Treatment of Wastewater in a Dredged Soil Waste Disposal Site, Using Sand Filtration and Higher Organisms

The North Section of the Osaka North Port Solid Waste Disposal Site was used from 1973 to 1986, and after that landfilling work was switched over to the South Section. The water quality of the site caused no problem in the early phase of landfilling; however, following the progress of landfilling, increases of COD and SS were brought about in the stabilization pond through logarithmic growth of phytoplankton and it was found necessary to treat wastewater, removing suspended solids mainly composed of phytoplankton. It was found that sand filtration is effective for water pollution control from the Site. The problems are filtration blockade and a low filtration rate, that is 6.3 m3/m2/day, with a head loss of 1 m. Treatment by higher organisms was found to apply, depending upon the conditions of the Site.