Mumbai university > Civil > SEM 8 > Industrial Waste Treatment

Marks: 10M

Year: Dec 2014, May 2013, May 2012

Characteristics of waste water of alcohol industry:

• Rate of flow: 1 MLD

• DO: -------

• BOD: 12000-40000 mg/l

• COD: 30000-75000 mg/l

• Alkalinity: 350-500 mg/l

Process of alcohol generation:

• The beverage alcohol industries utilize different grains, malted barley and molasses as raw materials. On the other hand the molasses (black strap types) are exclusively used as raw materials in the alcohol industry.

• The final stages being identical, the preparation of the fermenting medium or mash is slightly different in these two industries.

• In beverage alcohol industry, the preparation of mash consists of preparation of green malt, preparation of cooked slurries of the grains, mixing of the above two followed by pH adjustment and nutrient supplementation.

• On the other hand in molasses distilleries, the preparation of mash consists of dilution by water to sugar content of about 15%, pH adjustment to 4-4.5 to prohibit bacterial activities and nutrient addition.

• The yeast suspension is prepared separately in the laboratory with part of the diluted molasses and then inoculated into the mash for fermentation under controlled conditions.

• The fermented liquor containing alcohol is then sent taover head tank without separation of solid materials.

• The same is then degasified, and then the alcohol is stripped leaving a spent wash. The crude alcohol is then redistilled and stored in vats.

• Some of the beverage alcohols like gin attain their final form at this stage, some others like whisky require aging in charred oak wood barrels. The byproducts from the alcohol industry are: yeast spills, yeast sludge, spent wash, acids and salts, sugar spills and overflow waste.