The operation of the core stages of a sediment remediation process - the conditioning of anoxic sludge by plants and the solid-bed leaching of heavy metals using microbially produced sulfuric acid - was tested on a pilot scale using a highly polluted river sediment. Sediment conditioning was performed in 50 m3 basins at sludge depths of 2 m. During one vegetation period the anoxic dredged sludge turned into a soil-like oxic material and became permeable to water. Reed canary grass (Phalaris arundinacea) was found to be best suited for conditioning. Bioleaching was carried out in an aerated solidbed reactor with a 2,000 L working volume using soil-like oxic sediment supplemented with 2% sulfur. When applying conditioned sediment, the heat production by microbial oxidation of organic matter increased the temperature up to · 50°C, which temporarily inhibited the sulfur-oxidizing bacteria. Under optimum process conditions the heavy metals were solubilized within a few weeks. Zn, Cd, Ni, Co and Mn were leached by up to 80%. Cu was partially dissolved, while Cr and Pb proved nearly immobile. Sediments conditioned by plants and long-term stored oxic sediments were leached with the same efficiency. In total, 60-65% of the heavy metal load was removed after 6 weeks.