Processing Watered Toxic Waste of Pig and Poultry Farming in Sub- and Supercritical Water (Review)

The treatment of pig and poultry farm waste (hazard class III waste) with water at the parameters above its critical point ( T > 374°C, P > 22.1 MPa) is considered as one of the promising methods of processing them in an environmentally friendly way. The works on liquefaction, carbonization, and gasification of pig manure and chicken droppings in sub- and supercritical water are analyzed. The problems related to the practical implementation of waste processing in supercritical water-oxygen fluid are discussed, which primarily include the high cost of compressed oxygen, the inhomogeneous composition of wastes and the presence of solids in them, precipitation of salts, and corrosion of structural materials. It is shown that, due to the high water content in the wastes and the low calorific capacity of the organic matter contained in them, the practical implementation of such treatment under autothermal conditions requires the use of additional fuel.