Process for drying solid organic substances in aqueous phase, such as residual sludge from purification processes, which comprises the steps of: - feeding a continuous flow of said organic substances having a water content greater than or equal to 50% by weight into a turbodrier comprising a cylindrical tubular body with horizontal axis, equipped with inlet and outlet openings (5, 6), a heating jacket for bring the inner wall of the tubular body to a predetermined temperature, a bladed rotor extending inside the cylindrical tubular body where it is made to rotate at speeds between 15 and 40 m/s, so as to disperse said continuous flow of organic substances into a flow of particles of organic substances; - centrifuging said particles of organic substances against the inner wall of the turbodrier heated to a temperature above 130°C, with formation of a thin, dynamic, highly turbulent tubular fluid layer, which advances substantially in contact with said inner wall of the turbodrier towards said outlet opening; - continuously discharging, from said turbodrier, a flow of organic substances in disgregated wet solid form having a water content of no more than 45% by weight, preferably between 20 and 40% by weight; - continuously feeding said flow of disgregated wet solid into a drier operating at a temperature lower than or equal to 160°C; - continuously discharging a flow of dry product having a water content of no more than 20% by weight from said drier; wherein the residence time of said organic substances fed into said drier as disgregated wet solid is greater than the residence time of said solid organic substances in aqueous phase fed into in said turbodrier. - feeding a continuous flow of said organic substances having a water content greater than or equal to 50% by weight into a turbodrier comprising a cylindrical tubular body with horizontal axis, equipped with inlet and outlet openings (5, 6), a heating jacket for bring the inner wall of the tubular body to a predetermined temperature, a bladed rotor extending inside the cylindrical tubular body where it is made to rotate at speeds between 15 and 40 m/s, so as to disperse said continuous flow of organic substances into a flow of particles of organic substances; - centrifuging said particles of organic substances against the inner wall of the turbodrier heated to a temperature above 130°C, with formation of a thin, dynamic, highly turbulent tubular fluid layer, which advances substantially in contact with said inner wall of the turbodrier towards said outlet opening; - continuously discharging, from said turbodrier, a flow of organic substances in disgregated wet solid form having a water content of no more than 45% by weight, preferably between 20 and 40% by weight; - continuously feeding said flow of disgregated wet solid into a drier operating at a temperature lower than or equal to 160°C; - continuously discharging a flow of dry product having a water content of no more than 20% by weight from said drier; wherein the residence time of said organic substances fed into said drier as disgregated wet solid is greater than the residence time of said solid organic substances in aqueous phase fed into in said turbodrier.