Distillieries - Environmental Clearance

Distilleriesformed by fermentation and present in cider, mead, beer, wine, and spirits to varyingdegrees), or for production of so-called silent spirits. These, however, have no practicalrelevance to pollution.3.3 Distilling Processes Based on Raw MaterialsIn terms of raw material and process differences, two types of distilleries are in existencein India. Process descriptions of each are discussed in subsequent sections.3.3.1 Distilled liquor based on cerealsSequentially, cereal-based distilleries involve the following major process steps.Milling - Reduction of particle size prior to hydrationCooking - Hydration and gelatinization of starchConversion - Enzymatic hydrolysis of starchFermentation - Production of ethyl alcoholDistillation - Product recoveryThe processes of milling, cooking, conversion and fermentation in cereal baseddistilleries are similar to those followed in breweries with the exception that the brewingstep is not carried out. In these distilleries, mashing, which includes cooking andconversion as in the case of breweries, is carried out in different types of mash tuns whichare large cookers. Conversion of grain and malt occurs at a temperature of 50-70°C.Requirement of water during cooking is 5-7 L/kg of grain and that during malt slurrypreparation is 8-9 L/kg of malt.Mashing normally takes between 2.5 and 3 hours, at the end of which, the mash is cooledto a temperature of 25-30 o C and transferred to fermenters where it is inoculated withcultured yeast.Preparation of yeast for inoculation of the fermenters is done initially in the laboratoryand the yeast population is grown in successively increasing stages in the plant wheremalt mash of about 15% solid concentration is inoculated in each stage with 2 to 5% byvolume of culture from the preceding stage. Each inoculation stage lasts for about 24hours. The final composition in the main fermenters is generally maintained at 8-12 L ofwater for every kg of grain processed.The fermented beer which contains 6.5 to 8.5% ABV is pumped into the upper section ofthe beer still (distillation column). Direct steam, entering the bottom of this column,strips the alcohol from the beer and passes into another distillation column known as thealdehyde column where it is again steam stripped and the main stream of alcohol at lowproof is pumped from the base of the aldehyde column into the rectifying column forfurther purification. Alcohol of about 190° proof is drawn from the top of the rectifiercolumn while water is discharged from its base.Fusel oil is a by-product withdrawn three or four plates above the feed point in thealdehyde column and constitutes about 10% of the product stream. The lighter fractions,known as the heads and consisting mainly of aldehyde, esters, etc., are withdrawn fromthe top of this column and constitute about 5% of the product stream.TGM for Distillery Industry 3-6 August 2010