Abstract: A paper having a brightness of at least about 81% is provided. The paper comprises pulp having at least about 40% lignin, and a coating comprising a pigment to increase the brightness.

Abstract: A supercritical water oxidation reactor is alternately supplied with a feed stream and a flushing stream. The feed stream contains organic and inorganic materials. The organic materials are oxidized under supercritical conditions in the reactor and the inorganic materials precipitate out of solution under the same conditions. The flushing stream is a solution in which the inorganic material is soluble. More than one supercritical water oxidation reactor may be connected so that the feed stream is alternately supplied to each reactor. During the period when the feed stream is being supplied to a reactor the effluent from the reactor is cooled to a temperature at which inorganic precipitates are soluble and is then supplied as a flushing stream to one or more of the remaining connected supercritical water oxidation reactors.