Abstract: By providing a hide processor or tanning drum with appropriate equipment for applying vacuum and microwave energy concurrently, these tanning machines become a versatile means of drying to yield dry hides that contain no salt yet store better than salted hides. In this novel process, fresh hides are loaded into the tanning machine where they are washed, demanured and then dried in situ under vacuum with concomitant application of microwave energy. Because the dried hides thus obtained are soft and pliable, they can be mechanically fleshed or shaved to remove the subcutaneous tissues rich in collagen and fat. Alternatively, the hides may be first dried in the tanning machine to below 35% moisture content and degreased using a solvent such as hexane. The solvent remaining in the hides after decantation of the unabsorbed liquid is vaporized at low temperature using vacuum and microwave energy. The hides are then dried in situ to the desired final moisture content.

Abstract: Improvements in the treatment of lime-sulfide unhairing wastes from both salt-cured and unsalted hides are provided. After undissolved lime is flocculated out of the waste of a salt-cured hide and the supernatant acidified to liberate hydrogen sulfide, the hydrogen sulfide is flashed off under reduced pressure at about from 100.degree. to 150.degree. F. The waste from unsalted hides is sparged with carbon dioxide prior to flocculation, the sparged waste is flocculated with a strongly cationic polyelectrolyte, and the hydrogen sulfide flashed off from the acidified supernatant liquid.