Primer on Bioproducts - BIOCAP Canada

Bioprocesses for Bleaching andLeachingThe enzymes and metabolic systems of microorganismshave also been useful in the textile,papermaking and mining industries. In theconventional bleaching and treatment of paperand fabric, for instance, large amounts of water,energy, bleach and other chemicals are neededto whiten the fibres and, afterward, to rid theproduct of the leftover chemicals. Enzymesfrom biological sources can help in the bleaching,or they can assist with washing and cleaningthe material once bleaching is complete.Iogen Corporation has been a world leader inthe development of the enzyme xylanase tohelp with the bleaching of wood pulp for papermills. This enzyme, originally isolated from thecells of a fungus, works by making the tough,lignin structure of the wood pulp morepermeable to the bleach. As a result, less waterand chlorine is required in the process. Theprocess is also used by Domtar Inc. of Canada.As another example, Japan’s Oji Paper Co. usesthe enzyme catalase to rid fabric of hydrogenperoxide after bleaching. This enzyme reducesthe temperature and amount of water requiredto wash away the bleach.Meanwhile, bacteria have been put to work inthe mining industry. The South African miningcompany Billeton uses bacteria for leachingcopper from the sulphide ore in which it isfound. The bacteria, which works by oxidizingSource:ce: www.comstock.com/cathe sulphur and iron in the ore, saves the time,energy and expense associated with shippingthe ore to a smelter to extract the copper. It alsocuts emissions of sulphur oxides, arsenic andother toxic chemicals.Budel Zinc of the Netherlands uses bacteria totreat the wastewater from its zinc refineryprocess. The sulphate-reducing bacteria capturetrace amounts of zinc and other metals fromthe acidic wastewater and settle them out as aprecipitate. The process is more successful thanconventional methods for removing thesecontaminants from wastewater, and it avoids thebuild-up of heavy metal contaminated sludgethat was a byproduct of the conventional process.PRIMER ON BIOPRODUCTS37