a process for treatment of waste containing organic material , phosphorous and water in suitable amounts to be a pumpable sludge and in order to be oxidizable through supercritical water oxidation , comprises the steps of : putting the sludge into conditions being supercritical for water ; adding oxidant , particularly , oxygen to the sludge , wherein the organic material contained in the waste is substantially completely oxidized by means of supercritical water oxidation ; separating the phosphorous from water and from carbon dioxide formed during the oxidation ; and recovering the phosphorous by means of dissolving the phosphorous in an alkali .