Abstract: A method for precipitating metal waste is characterized in that the waste which contains one or more dissolved metal salts, is mixed with a boron compound, and the pH is adjusted to a value at which precipitation takes place in the presence of precipitation nuclei necessary for the formation of metal borates.

Abstract: A gas is purified using both mechanically atomized liquid and liquid dispersed by electrostatic atomization at asperities arranged at surfaces of emitting electrodes. The concentration of washing liquid between the make-up pipeline and discharge pipeline is obtained, on the one hand, by recycling using atomization pipes of a group of electrodes for the run-off liquid collected by an accumulation tank and, on the other hand, using a back-flow of the liquid between successive accumulation tanks through interconnecting pipelines. A physical and/or chemical treatment line for the liquids and the sludges is also associated with the gas treatment line.