Multiple treatment of liq. manure and thin sludge - by forming fine-dry material, useful as non-noxious fertilisers

摘要

After preliminary drying, e.g. by filter press or in settlement tanks, liq. manure or thin sludge is divided into coarse and fine solids and a residue, mainly of water. Warm air reduces residual moisture content of the coarse fraction to 3% or less. Hot air drying of the filtrate aq. in a spray tower, produces fine solids, while clean residual water is condensed on a cold surface. A cyclical system with filter sections, spray tower, cyclone etc. forms both hot and cold material. Heat from the circuit dries out raw material, while cold is used in condensing distillation. Waste power draws electrical generators. At any suitable stage to circulating material is sterilised, e.g. by microwaves. ADVANTAGE - Reduces external pollution of treated farming land, as compared with simple spreading. System is simple, with low energy demand, since balance between drying and condensation yields useful waste heat.