METHOD AND INSTALLATION FOR TREATING INDUSTRIAL, AGRICULTURAL AND URBAN OR AGRICULTURAL WASTE, IN PARTICULAR PIG SLURRY

摘要

The invention concerns a method and an installation for treating liquid waste containing water and diluted polluting organic substances, such as pig slurry, or agri-food effluents. The invention is characterised in that it comprises at least: a) a step which consists in thermal evaporation (1) of a substantial proportion of said water; and b) a step (2) which consists in incinerating the concentrate obtained in the preceding step. Preferably, it consists in using a mechanical vapour recompression evaporator (1) combined with an incinerator (2) with fluidised bed and recycling (4) of the heat-exchanging material, in particular sand, and pre-mixing (5) said heat-exchanging material with at least a substantial part of the concentrate (9) obtained in the evaporation step. Said method efficiently destroys the slurry, in particular nitrates, by an inexpensive process, enabling to recuperate its useful elements, among which water with COD 50, and the phosphates in the form of dry powder reusable as fertiliser, and producing only either useful or non-polluting agents.