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Abstract:
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Leather is manufactured from a variety of animal skins in three main stages; pre-tanning, tanning and finishing. Pre-tanning refers to the number of processes involved in removing unwanted components from the skin. This includes soaking, fleshing, unhairing, deliming and pickling. Tanning is essentially the chemical stabilization of the true skin. Chrome tanning, vegetable tanning and aluminium tanning are commonly used to produce different quality of leader. As leader manufacturing involves many steps of processes, it produces also effluent whose rate of discharge, pH and composition vary considerably. Generally speaking tannery effluents are strong effluents with high oxygen demand, sulfide content, suspended solids with inorganic dissolved solids, mainly chloride and sulphate. In tanneries most of the objectionable waste originate from the pretanning and tanning processes. Anaerobic treatment has the advantage of high organic load, low energy consumption, small amount of sludge produced and recovered methane gas as useful energy. Recently anaerobic treatment has been considered as analternative treatment method for tannery effluent. Laboratory scale upflow anaerobic filter and upflow anaerobic sludge blanket were used to investigate the feasibility of anaerobic treatment of tannery effluent. Batch bottle bioassay tests were also conducted to assess the toxicity and methane potential. /Kir11 |