Browsing by Author "Guche, Mesfin"

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    Recycling of Dusted Salt From Raw Hides/Skins for Pickling Operation Using Supernatant (Waste Liquor) From Chrome Recovery Unit: a Case of Dire Tannery
    (Addis Ababa University, 2018-06-05) Guche, Mesfin; Tekola, Beteley (PhD); Abebe, Aynalem (PhD)
    Since the scope for green processing is limited in Ethiopia, sodium chloride is widely used to preserve raw hides and skins. It contributes to a high volume of total dissolved solids (TDS) in the soak waste liquor. A large amount of the salt sticking to the hide and skin surface can be removed by shaking the hides mechanically or manually. Among the different desalting methods DODECA wooden frame was found suitable for desalting skins and hides Though the quantity of salt removed varies with the method of desalting, it is generally in the range of 3.6 – 11.8% on the weight of raw stock taken for desalting and the amount of water used for soaking operation reduced in the range of 4.5 – 4.8 % on account of desalting of raw stock. Though the dusted salt from desalting operations contains many impurities, a fairly clear salt solution can be obtained by dissolving the salt recovered in water, simply screening it and then clarifying it using poly- aluminum chloride. Demonstrations showed that the salt solution so obtained could be safely used in pickling operations. Desalting of raw stock reduces the chloride level in the composite tannery wastewater by about 41.9%. Practically, it has been seen that chloride in the composite effluent of a tannery processing salted raw hides/skins to semi-finished leather is reduced from 1560 mg/l to 906.4 mg/l on account of desalting of raw stock, collection and proper disposal of the dusted salt. Though desalting may not directly result in considerable financial benefit, indirect benefits include more efficient soaking and reduction in the volume of soak liquor discharged.