Clarifying sludge processing and pasteurising - by adding lime in specified quantities according to sludge dry solids content, to produce a fertiliser

摘要

Clarifying sludge is worked up and pasteurised by adding CaO in quantities depending on sludge dry solids content. At %-age concns. 10% dry solids, the CaO:dry solids ratio corresponds to the %-age concn. of dry solids in sludge. Above 10% dry solids content, the CaO:dry solids ratio kept up is 1:11 to 1:25. The slurry obtd. is left to react out-of-doors. Reaction by re-heating of compsn., e.g. by adding air to re-heaped mixt., yields a crumbly prod., easily used as fertiliser. Process yields a high quality fertiliser which does not acidify the soil; prevents pollution and obviates burning of sludge and the need for centrifuging- and pasteurising plant. CaO quantity added can be very small. Malodorous constituents and weed seeds are destroyed.