A plant for the disposal of wastes includes a supercritical water oxidation reactor, a supercritical water gasification reactor, and a feeding system configured for feeding at least two organic currents of wastes to the supercritical water oxidation reactor and supercritical water gasification reactor and configured for feeding at least one aqueous flow within said plant. The feeding system is configured for feeding the at least one aqueous current with a series flow through the supercritical water oxidation reactor and supercritical water gasification reactor. The feeding system is configured for feeding the at least two organic currents of wastes with a parallel flow through the supercritical water oxidation reactor and supercritical water gasification reactor and so as to selectively feed each of the organic currents of wastes to the supercritical water oxidation reactor or to the supercritical water gasification reactor.