Abstract: An apparatus and process for the removal and recovery of sulfides from tannery waste water or liquor. The apparatus comprises a closed vessel, the sulfide-bearing liquor is introduced into a first or acidulation zone of the vessel and mixed with acid to decrease the pH, preferably to a value below 4.0, and generate hydrogen sulfide. The acidified liquor is then overflowed into a second or desorption zone of the vessel and slowly agitated and conveyed through the second zone by disc conveyors to release the hydrogen sulfide gas from the liquor. A slight vacuum is drawn on the vessel causing the released hydrogen sulfide gas to be drawn into a third reaction zone of the vessel, where the gas combines with sodium hydroxide solution to form sodium sulfhydrate. The effluent from the second zone can be filtered or dewatered and the filtrate discharged to a disposal site while the proteinaceous solids can be recovered for use as fertilizer.

Abstract: An improved hide processing machine has a hide-treating drum supported for rotation about a central longitudinal axis to retain and tumble hides and treating fluids at a closed end of the drum. The drum includes helical partition means extending across the interior of the drum and spirally along the drum axis from its closed end toward its open end, thereby dividing the drum into at least two longitudinally-extending spiral compartments. The partition means prevents movement of hides from one such compartment to another during rotation of the drum, and includes fluid-transmitting openings for free movement of treating fluid between such compartments. The helical partition means can provide a conveying force for retaining or discharging such hides when the drum is rotated in an appropriate direction.