Fertiliser prodn. from sewage sludge - uses continuous proportioning and mixing of sludge with additives to produce crumbs of prod.

摘要

Prodn. of fertiliser from sewage sludge comprises adding rock wool and lime or other cpd. fertiliser to ground dewatered sludge pref. at about 20% solids content. The constituents are mixed continuously and homogenised by extrusion under pressure through an adjustable orifice before being broken up into crumbs suitable for spreading on the land. Used for prodn. of a compound fertiliser esp. from sludge contg. up to 80% moisture; the process produces material which is much easier to spread than the dewatered sludge on its own.