BREWERIES AND DISTILLERIES EFFLUENT

MANAGEMENT

Akhil ShettySID: 13201003

M.E. 2nd SemEnvironmental Engineering

BREWING INDUSTRIES

• In the food industry, the brewing sector holds a strategic economic position with the annual world beer production exceeding 1.34 billion hectoliters

• Beer is the fifth most consumed beverage in the world behind tea, carbonates, milk and coffee.

• During production, beer alternately goes through three chemical and biochemical reactions (mashing, boiling, fermentation and maturation) and three solide liquid separations (wort separation, wort clarification and rough beer clarification)

• water consumption, wastewater and solid-liquid separation constitute real economic opportunities for improvements in brewing

DISTILLERY INDUSTRY

• The range of products from distilleries includes Industrial alcohol, rectified spirit, silent spirit, absolute alcohol, beverage alcohol etc.

• Production of ethyl alcohol in distilleries based on cane sugar molasses constitutes a major industry in Asia and South America.

• The world’s total production of alcohol from cane molasses is more than13 million m3/annum

• The aqueous distillery effluent stream known as spent wash is a dark brown highly organic effluent and is approximately 12-15 times by volume of the product alcohol.

• It is one of the most complex, troublesome and strongest organic industrial effluents, having extremely high COD and BOD values.

COMMON CHARACTERISTICS OF PRODUCTS FROM BOTH INDUSTRIES

• Products from both industries are obtained through the biochemical process of fermentation by yeast, using carbohydrates as the raw material.

• All the products contain ethyl alcohol in different proportions.

ORIGIN OF BREWERIES WASTE

Making of beer essentially consist of two stages• Preparation of malt from grains like barley • Brewing the barley

The malt from malt house is then transported to the brewing section, where the wort, the medium of fermentation is prepared by making a mash of coarse grained malt with hot water and by transforming the starch to sugar by boiling with hos

Brewery wastes originate in both

these stages

CHARACTERISTICS OF BREWERIES WASTE

• Spent water from steeping process from malt house contains a large amount of organic soluble solids indicated by a high BOD in the order of 400-800 mg/l and low suspended solids conc.

• Waste from brewing plant contains a high suspended solids and also a high BOD

• Malt house waste is alkaline in nature • Brewing plant waste is acidic

COMPOSITION OF MALT HOUSE AND COMBINED BREWERY WASTE

Malt house waste

Brewery waste

pH 6.9 - 9.5 4.0 – 7.0 COD, mg/l 31 – 175 30 – 1225BOD, mg/l 20 – 204 70 – 3000Total solids, mg/l 428 – 700 272 - 2724Suspended solids, mg/l 22 – 339 16 - 516Total Nitrogen (N), mg/l 14 - 56 7 – 42

Brewing process and main waste.

ORIGIN OF DISTILLERIES WASTE

• The beverage alcohol industries utilizes different grains, malted barley and molasses as raw material

• The Industrial alcohol industries use molasses (black strap type) exclusively as raw material

In beverage alcohol industry, the preparation of mash consist of i. Preparation of green malt ii. Preparation of cooked slurries of the grain iii. Mixing of the above two followed by pH adjustment, and nutrient

suplimentation

In molasses distillery, preparation of mash consist of i. Dilution by water to a sugar content of above 15% ii. pH adjustment to 4.0 – 4.5 to prohibit bacterial activity iii. Nutrient addition

CHARACTERISTICS OF DISTILLERIES WASTE

• Spent wash is the major polluting component of the distilleries and it is reported to be 10 to 15 times the final product in volume

• Other pollutants includes yeast sludge which is deposited in the bottom of fermentation vats.

• Malt house wastes also contributes towards pollution in beverage alcohol distilleries

• Floor washes, cooling water waste and waste from operation of yeast recovery also contributes.

CHARACTERISTICS OF COMBINED WASTE AND SPENT WASH

Combined waste Spent WashpH 3.9 – 4.3 3.5 – 3.65COD, mg/l 27900 – 118000 118000BOD, mg/l 12230 – 40000 41380 Total solids, mg/l 16640 – 26000 99000Suspended solids, mg/l 4500 – 12000 350Total Nitrogen ----- 1135Alkalinity 380 – 510 ----Color Dark BrownDO ----- NILRate of Waste flow 0.9 – 1.0 MLD ----

EFFECTS ON RECEIVING STREAMS

• All the types of wastes discussed earlier are not toxic to the aquatic life of the receiving stream.

• But due to high BOD content, they deplete the DO of the receiving water.• Anaerobic decomposition of organic solids causes nuisance over a fairly long

stretch of the stream. • The condition further deteriorates due to the strong growth of sewage fungi.

The dark color stream renders it unaesthetic.

EFFECT ON SEWERS

• Brewery is of comparatively lesser strength, so it can be discharged in a fresh condition into the sewage to the extent of 3-5% of the domestic sewage.

• A strongly acidic or putrefied Brewery waste will disrupt the normal biological activity of the waste treatment plants.

• The very high BOD content of the distillery waste makes it non amenable to the aerobic biological treatment, and as such it cannot be discharged into a municipal sewerage system directly.

TREATMENT OF WASTE

• Brewery waste being less strong can be treated by aerobic biological treatment, after screening and neutralization.

• Usually, the Biological treatment is accomplished by a two stage process for 90 – 94% BOD reduction.

• A two stage biological method of treatment consist of an anaerobic treatment, followed by an aerobic treatment of the waste has been widely accepted.

• A single stage digester is adopted for the anaerobic treatment when land availability is limited.

• For BOD reduction of 90.8% a BOD loading of 2.5 kg/m3/ day and detention time of 15 days is suggested (Subbarao et. al).

• Production of H2S impairs the anaerobic digestion, as soluble sulphides are toxic to the micro-organisms. Conversion of sulphides to insoluble ferric sulphides by addition of iron salts improves the condition

• Neutralization of waste help in eliminating odour nuisance • 90 – 95% BOD reduction can be achieved by two stage anaerobic lagoon

system• Effluent from digester or anaerobic lagoon has to be further treated in

aerated lagoon or in oxidation ditch. • Aerated lagoon effluent requires further treatment in a polishing lagoon for

24 hours detention time.

Flow sheet for the treatment of Brewery Waste

Flow sheet for waste treatment of a large Distillery complex

BY-PRODUCT RECOVERY

• Segregation of Yeast sludge for animal feed is practiced in some distilleries • Yeast powder of pharmaceutical grade can be obtained from yeast sludge

and spent wash mix• Animal feed is derived from the brewery waste• It has been reported that about 3.85 tonnes of Potash can be derived from

about 320m3 of spent wash.