Factors affecting the choice of granular activated carbon for brewery filters.
Granular activated carbon filters are commonly used to remove taints from potable water, including brewing liquor. The principal causes of such taints include substances produced by algae and fungi, as well as reaction products formed as a result of the use of chlorine based disinfectants. Activated carbon can be produced from a variety of plant materials, including fossilized plant matter. For potable water treatment purposes, coal and coconut shells are the preferred sources as they are less likely to carry taints of their own than other common sources such as wood or peat charcoal. The properties of activated carbon used as parameters for specification purposes include its surface area per unit of weight, its pore volume and its pore size distribution. Activated carbon made from coconut shells tends to have mainly small pores (under 2 nm) whereas in that made from coal most of the pores are larger (over 5 nm). This means that coconut carbon is more effective for the removal of small molecules such as trihalomethanes, while coal carbon is more effective against larger molecules such as pesticides. The effects on activated carbon filter performance of the level of natural dissolved organic matter in the water being treated, ozone treatment of water before activated carbon filtration, variations in the concentrations of the contaminants in the incoming water and competition between different substances varying in their propensity to be taken up by activated carbon are discussed and actual applications in liquor treatment at five commercial breweries are described.
Keywords : activated carbon brewing liquor decontamination performance selection