Distillieries - Environmental Clearance

Distilleriesa) MaltryMalt is produced from grains, usually barley and less commonly wheat or other cereals.The major process steps are steeping, germination and kilning. Steeping is done to cleanthe grain and initiate germination. The operation comprises adding water in adequatequantity, along with certain additives if required. The water is changed two-to-four timesand a total steep cycle of 24-60 hours is employed, as determined by the subjectivejudgement of the maltry depending on a variety of factors, from dormancy of the grain toclimatic conditions. The germination or malting may be done in a variety of ways. InIndia, the common practice is floor malting. In this the steeped grain is put in a couch,and when germination begins, it is spread on the floor for 7-10 days, depending on thenature of the grain and germination conditions. When it is judged that an optimumamount of enzymatic breakdown of the original high molecular weight compounds hastaken place, the green malt is kilned to arrest germination and fix the desirable propertieslike flavour, aroma and viability. The kilning process comprises of initial drying at 30-40°C followed by curing at 70-105 °C.The plant practices that lead to pollution are:Throwing the skimmings from steep vessels on the floor, which are eventuallydrained during floor washing.Spillage of grains during manual transfer from one germination box to another;Spillage of rootletsIn general, the wastewater in open drains of maltries is rich in suspended solids andcreates a characteristic foul odour due to deterioration.b) BreweryIn the breweries, the malt is milled to very coarse flour called ‘grist’, which is thenextracted in water in a process called ‘mashing’. There are three chief methods ofmashing, viz. infusion mashing, decoction mashing and double mashing. In India, thecommon practice is decoction mashing in which, unlike in the other systems, cooking ofthe malted cereal is not involved. The extract from the mashing step, called ‘sweet wort’is fed into ‘Iauter tun’ where about 25-30% of the grain fed for mashing is removed. Thesweet wort is then boiled in the ‘brew kettle’ to arrest the enzymatic action, sterilize it andprecipitate some protein matters. Hops, which impart the characteristics flavour andbitterness to the beer, and sugar are also added in the brew kettle. The spent hops areseparated in a ‘hop jack’ or on a strainer, and the ‘bitter wort’ is passed throughwhirlpools, where it entraps some air and some of the resins are precipitated. The bitterwort is cooled to 10-15°C and fermented by yeast over a period of 6-14 days, the usualcycle in India being 10 days. The ‘green beer’ so obtained is lagered for 1-2 months,during which much of the suspended matter settles down. It is then filtered, bottled andpasteurised.The brewery in general is a clean industry. Most plants are imported and foreign plantpractices are generally followed, as the brew masters are usually trained abroad. In someplants hop extract is used instead of hops, when there are no spent hops to be disposedoff.TGM for Distillery Industry 3-4 August 2010