2. Brewing industry
The word brewing means the combined process of preparing beverages from
infusion of sound grains that have undergone sprouting and subsequent
fermentation of sugary solution produced by yeast, whereby a proportion of
carbohydrate is converted to ethanol and CO2
Brewing process is energy intensive and uses large volumes of water and is
based on action of enzymes activated during malting and fermentation.
The Brewing industry employs number of batch type operations in processing
raw material to final beer product
3. Wastewater characteristics
CHARACTERISTICS AMOUNT
PH 6.5±4
COD(mg/l) 1250±100
NH3 –N(mg/l) 16±5
TN(mg/l) 24±3
SS(mg/l) 500±50
HEAVY METAL VERY LOW
WATER TO BEER RATIO 4-10 hl water/hl of beer
WASTEWATER TO BEER RATIO 1.3-1.8hl/hl less than water
to beer ratio
4. The brewing process
MILLING
The first step of Brewing is milling and carbon filtration takes place when malt grains are
transported from storage facilities and milled in a wet dry process.
During this process starch content of Mash is hydrolyzed producing liquor called ‘sweet
wort’. In infusion mashing process hot water of 160 o
f to 180o
f is used to increase efficiency
of wort extraction.
Wort boiling
This step involves wort boiling over a period of 1-1.5 hours at 4-12% evaporation rate .
The boiled wort is clarified via sedimentation, filtration and centrifugation and cooled .
Wort is cooled via air or liquid cooling medium at a pitching temperature of about 43-59o
f
and mixed with yeast while on its way to fermentation process .
Fermentation process
Occurs in large cylindrical vessels, where yeast metabolizes and fermentable sugar in wort
produces alcohol and CO2 .
After I-fermentation process yeast is removed by oscillating sieve, suction, conical
collector, centrifugation.
5. Beer Ageing /Conditioning
Beer is cooled and stored in order to allow yeast and other precipitates to settle and also
allows beer to mature .
Beer is held at conditioning temperature of 30o
f-50o
f for several days to a month and then
chill proofed and filtered .
Beer is sent to a bright beer tank before packing, specially treated water would be added
during conditioning .
Finally beer is cleaned of all harmful bacteria by heating at temperature of 140o
f before
bottling .
WASTEWATER TREATEMENT METHODS
Physical treatment
Chemical treatment
Biological treatment
7. Wastewater treatment methods
Physical treatment
FLOW EQUALIZATION : Flow equalization is a technique used to consolidate wastewater effluent
in holding tanks for “equalizing” before introducing wastewater into downstream brewery
treatment processes
SCREENING : The wastewater is first screened to remove glass, labels, and bottle caps, floating
plastic items and spent grains
GRIT REMOVAL : After the wastewater has been screened, it may flow into a grit chamber where
sand, grit, and small stones settle to the bottom.
GRAVITY SEDIMENTATION : Wastewater still contains dissolved organic and inorganic constituents
along with suspended solids. The suspended solids consist of minute particles of matter that can
be removed from the wastewater with further treatment such as sedimentation
Chemical treatment
Ph ADJUSTMENT : The pH of wastewater needs to remain between 6 and 9 to protect organisms.
FLOCCULATION : Enhances sedimentation performance by increasing particle size resulting in
increased settling rates.
8. Biological treatment :
AEROBIC :
ACTIVATED SLUDGE PROCESS : the wastewater flows into an aerated and agitated tank that is primed
with activated sludge. The suspension of aerobic microorganisms in the aeration tank, are mixed
vigorously by aeration devices which also supply oxygen to the biological suspension.
ATTACHED GROWTH FILM PROCESS : The second type of aerobic biological treatment system is called
“Attached Growth (Biofilm) Process” and deals with microorganisms that are fixed in place on a solid
surface. This “attached growth type” aerobic biological treatment process creates an environment
that supports the growth of microorganisms that prefer to remain attached to a solid material
ANAEROBIC :
UPFLOW ANAEROBIC SLUDGE BLANKET : , the wastewater flows in an upward mode through a dense
bed of anaerobic sludge. This sludge is mostly of a granular nature (1-4 mm) having superior settling
characteristics (>50 m/h). The organic materials in solution are attacked by the microbes, which
release biogas.The biogas rises, carrying some of the granular microbial blanket
MICROBIAL FUEL CELL TECHNOLOGY : MFC is a device to treat wastewater and produce electricity at
the same time. A variety of readily degradable compounds such as glucose and acetate, and
various types of wastewater such as domestic, starching and paper recycling plant wastewater, have
operated successfully as substrate in Microbial fuel cell
9. Practices to minimize the effluent flow
Heat exchangers : Compact heat exchangers are used to recover heat from hot
wart. Fermentation temperatures and cold liquor temperatures may vary for
different brews, so automatic temperature control will allow for flow optimization .
CIP : The cleaning of complete items of plant without dismantling or opening of the
the equipment, with little or no manual involvement. Process involves jetting or
spraying of surfaces under conditions of increased turbulence and flow velocity .
Good process design :Its good practice to design equipment with fewer parts and
no points where fluid accumulates, this will save cleaning time as well as water,
chemical and energy .
10. Fermentation vessels : Single pass cooling requires large amount of water
whereas closed loop systems will regulate the cooling water through
fermenters cooling system via pumps and control systems. It’s ensured that
pump size is adequate to cope up with the maximum flow of cooling tower
when all fermenters are in use.
fig: Heat exchangers fig: CIP tanks
