Abstract: Solid wastes, and wastes to be compacted, are pretreated for introduction into underground salt cavities or salt caverns via a downpipe under the force of gravity by a process in which solid, uncomminuted or comminuted or finely divided to very finely divided wastes are mixed with waste sludges in a ratio such that a material results from which moldings are produced, with or without the addition of a binder, in the form of granules, agglomerates or pellets by a granulation method, or in the form of flakes by a pressing method, the flakes being comminuted to give small moldings, and, if appropriate, the moldings are surface-dried or dried completely, the moldings which are free-flowing under the force of gravity are then trickled into the salt cavity or into the salt cavern and form a pile therein until the said cavity or cavern is substantially full, and, if required, the salt cavity or the salt cavern is closed.

Abstract: A liquid waste with a pH of 7 or more, which has been adjusted above ground if necessary, is treated above ground to produce a pumpable mixture, which has aboiling point above 85.degree. C.,flash point above 65.degree. C.,vapor pressure at 60.degree. C. of up to 0.5 kp/cm.sup.2, andviscosity of less than 300 cPand which forms no toxic or flammable gases. The mixture is then conveyed to a salt cavity and allowed to stand until phase separation has occurred before the resulting liquid phases are separately drawn off for further treatment or disposal.