In design of revetments for land reclaimed with disposed waste, it is important to prevent waste from leaking out through revetments. In this sutdy, purification effect of backfilling sand is investigated by laboratory experiments under simulated site conditions, which include such as grain size of sands, residual water level, clay type and organic sediments etc.
　Three series of experiments are conducted, which include that on sand filtration of clay suspension, that on adsorption of heavy metal to clay particles, and that on adsorption of organic matter to clay, sand filtration and discomposition of organic matter.
　From these experiments it is clarified that suspended solids can be almost perfectly filtered by backfilling sand and that heavy metal and organic matter can be removed to some degree under a suitable condition.