Industrial examples tannery industry

The ELM pertraction technology has good potential for more applications at industrial scale in the near future. The industries in question might include metal mining and refinery operations (precious metals and platinum group metals are good examples), tannery industry (recovery of hexavalent chromium), and processing of nuclear wastes (recovery of uranium, strontium, and other metals). 

The relevant legislation for tanneries regarding the use of chemicals can be found both in legislation regarding environmental permits for the industrial installations which in some cases addresses substitution of chemicals. One example of this is the EU Industrial Emissions Directive [4] which regulates emissions from industrial installation within the EU. One key aspect in this directive is how problematic chemicals should be substituted to more environmentally friendly alternatives by tanneries. 

Other important toxicological con tarn in ants that can be found in waste-waters are metals. Toxic heavy metal ions are introduced to aquatic streams by means of various industrial activities viz. nfrning, refining ores, fertilizer industries, tanneries, batteries, paper industries, pesticides, etc., and possess a serious threat to the environment. The major toxic metal ions hazardous to humans as well as other forms of hfe are Cr, Fe, Se, V, Cu, Co, Ni, Cd, Hg, As, Pb, Zn, etc. These heavy metals are of specific concern due to their toxicity, bioaccumulation tendency, and persistency in nature [190]. The SLM technique has been widely apphed for the transport and recovery of almost ah important metals from various matrices an exceUent review of ah aspect of metal permeation through SLM (covering both theoretical and practical considerations) is available [191]. Here, only some selected recent examples of the use of SLM for metal separation whl be presented. 

Clams, oysters, and mussels accumulate chromium from the medium or from contaminated sediments at comparatively low concentrations. For example, oysters subjected to 5.0 (xg Cr+ /L for 12 weeks contained 3.1 mg Cr/kg DW in soft parts and retained 52% of the accumulated chromium after they were transferred to chromium-free seawater for 28 weeks. Mussels (Mytilus edulis) subjected to the same dose-time regimen contained 4.8 mg/kg, but retained only 39% after 28 weeks of depuration. Both oysters and mussels contained higher residues after exposure to 10.0 jig Cr /L for 12 weeks 5.6 and 9.4 mg Cr/kg DW in soft parts, respectively, and both contained substantial (30-58%) residues after 28 weeks in a chromium-free environment. In studies with mussels and softshell clams (Mya arenaria), it was demonstrated that chromium in New Hampshire sediments (contaminated with Cr+ from tannery wastes) was bioavailable to clams by diffusion from seawater, and that both diffusion and particulate uptake were important pathways for mussels. Accumulation was observed at sediment chromium concentrations as low as 150.0 mg/kg. Kaolinite sediments containing up to 1200.0 mg Cr+ /kg produced the most pronounced adverse effects on filtration rates and ciliary activity of bivalve mollusks, leading the authors to conclude that chromium that has accumulated in areas affected by industrial wastes might have serious consequences to filter feeding bivalves. 

The use of enzymes in chemical processes saves vast amount of water for example, in the textile industry, about 70,000-90,000 L of water is used for 1 ton of knitwears, which can be saved by employing the enzymes. Considering that approximately 9 million tons of knitwear is produced annually worldwide, about 630 billion liters of water could be saved if produced using enzymes. Enzymes can replace many chemicals in the industrial processes giving the process more environmental friendly touch. For example, enzymes can reduce the use of sulfides in tanneries, which are serious source of pollution. Acids... 

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