DISTILLERY WASTEWATER TREATMENT AND DISPOSAL
Lt Col Mantha Nagaraj*, Dr Arvind Kumar**
*PhD Scholar, Environmental Engineering
Civil Engineering Department, Indian Institute of Technology (IIT), Roorkee – 247 667.
District Haridwar, Uttaranchal, India. (e-mail: manthanagaraj@yahoo.com)
**Professor & Head of Civil Engineering Department
Indian Institute of Technology (IIT) Roorkee – 247 667.
District Haridwar, Uttaranchal, India. (e-mail: prof_ak04@yahoo.com)
ABSTRACT
1.
One of the most important environmental problems faced by the world is management of wastes.
Industrial processes create a variety of wastewater pollutants; which are difficult and costly to treat.
Wastewater characteristics and levels of pollutants vary significantly from industry to industry. Now-a-days
emphasis is laid on waste minimization and revenue generation through byproduct recovery. Pollution
prevention focuses on preventing the generation of wastes, while waste minimization refers to reducing the
volume or toxicity of hazardous wastes by water recycling and reuse, and process modifications and the
byproduct recovery as a fall out of manufacturing process creates ample scope for revenue generation
thereby offsetting the costs substantially.
2.
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. Because of the high concentration of organic load, distillery spent wash is a potential source
of renewable energy. The paper reviews the status and appropriate treatment alternatives for disposal of the
distillery wastewater.
KEYWORDS
Distillery Spentwash, Revenue Generation, Byproduct Recovery.
INTRODUCTION
1.
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. Because of the high concentration of organic load, distillery spent wash is a potential source
of renewable energy.
2.
The 295 distilleries in India produce 2.7 billion litres of alcohol and generating 40 billion litres of
wastewater annually. The enormous distillery wastewater has potential to produce 1100 million cubic
meters of biogas. The population equivalent of distillery wastewater based on BOD has been reported to be
as high as 6.2 billion which means that contribution of distillery waste in India to organic pollution is
approximately seven times more than the entire Indian population. The wastewater from distilleries, major
portion of which is spentwash, is nearly 15 times the total alcohol production. This massive quantity,
approximately 40 billion litres of effluent, if disposed untreated can cause considerable stress on the water
courses leading to widespread damage to aquatic life.
MOLASSES
WATER
DILUTER
YEAST PROPAGATION
FERMENTER
FERMENTER SLUDGE
ANALYSER
RECTIFIER
ALCOHOL
SPENT WASH
SPIRIT RECEIVER
EFFLUENT TREATMENT
ALCOHOL MANUFACTURING PROCESS AND NATURE OF DISTILLERY
WASTEWATER
3.
In India bulk of the alcohol is being produced from sugar cane molasses. Molasses is a thick
viscous byproduct of the sugar industry which is acidic in nature, rich in salts, dark brown in colour and it
also contains sugar which could not be crystallized. For manufacturing alcohol, the Molasses is diluted with
water into a solution containing 15-16 % of sugars. This solution is then inoculated with yeast strain and is
allowed to ferment at room temperature. The fermented wash is distilled in a series of distillation columns
to obtain alcohol of adequate/ requisite strength and quality/specification. This alcohol is used for various
purposes including potable and industrial. For manufacture of alcoholic beverages, the alcohol is, if
required, matured and blended with malt alcohol (for manufacture of whisky) and diluted to requisite
strength to obtain the desired type of liquor/ Indian Made Foreign Liquor (IMFL). This is bottled in bottles
of various sizes for the convenience of consumers.
S.No.
Parameter
Range
1.
pH
4.3-5.3
2.
Total Suspended Solids
12,000-14,000
3.
Total Dissolved Solids
45,000-75,000
4.
B.O.D., 20 0C, 5 days
40,000-50,000
5.
C.O.D.
80,000-1,00,000
BIO-ENERGY POTENTIAL FROM DISTILLERY EFFLUENTS
4.
In India there are 295 distilleries producing 3.20 billion litres of alcohol generating 45 billion litres
of wastewater annually. The enormous distillery wastewater has potential to produce 1200 million cubic
meters of biogas. The post methanation wastewater if used carefully for irrigation of agricultural crops can
produce more than 85000 tonne of biomass annually. This biogas normally contains 60% methane gas,
which is a well-recognized fuel gas with minimum air pollution potential. If this source of energy is tapped,
it will fetch additional energy units worth 5 trillion-kilo calories annually. Besides, the Post Methanation
Effluent (PME) can provide 245000 tones of potassium, 12500 tones of nitrogen and 2100 tones of
phosphorus annually. Thus the manorial potential of effluent can be measured by the fact that one year’s
effluent can meet the potassium requirement of 1.55 million hectare land, nitrogen requirement of 0.13
million hectare land and phosphorus requirement of 0.025 million hectare land if two crops are taken in a
year.
Annual Bio energy Potential of Distillery Effluent in Various States of India
State
Units
AP
Assam
Bihar
Goa
Gujarat
Karnataka
MP
Maharashtra
Punjab
Tamilnadu
UP
WB
Rajasthan
Kerala
Pondicherry
Sikkim
Nagaland
J&K
HP
Haryana
Total
24
1
13
6
10
28
21
65
8
19
43
6
7
8
3
1
1
7
2
5
285
Capacity
(M Ltr/Yr)
123
2
88
15
128
187
469
625
88
212
617
24
14
23
11
7
2
24
3
41
2703
Effluent
(M Ltr/Yr)
1852
24
1323
218
1919
2799
7036
9367
1317
3178
9252
371
202
343
165
98
24
366
39
615
40,508
Biogas
(M m3)
50
0.7
35.7
6
51.8
75.6
190
253
35.6
86
250
10.1
3
9.3
4.5
5.5
0.7
11
1
16.6
1096.1
Total N
(tones)
566
7
397
65
576
840
2111
2810
395
953
2776
111
61
103
50
29
7
110
12
185
12,154
Total Ka
(tones)
11115
144
7940
1304
11511
16794
42219
56217
7902
1971
55512
22223
1215
2064
990
585
144
2196
234
3690
263,070
Biomass
(tones)
3704
48
2646
436
3838
5598
14072
18734
2634
6356
18504
742
404
686
330
196
48
732
78
1230
81016
PRESENT STATUS OF TREATMENT AND DISPOSAL
5.
Spent wash treatment is proposed by three different routes currently viz; (a) Concentration
followed by incineration, (b) Anaerobic digestion with biogas recovery followed by aerobic polishing and
(c) Direct wet oxidation of stillage by air at high temperature with generation of steam followed by aerobic
polishing. All of these processes are capital intensive. The incineration process involves an investment of
the order of 400% of the distillery cost, whereas the other two processes along with the secondary treatment
require an investment of 200-300% of the distillery cost. The unfavourable economics make it difficult to
implement these treatment processes on the plant scale. Because anaerobic digestion and wet oxidation are
less expensive, these alternatives are more attractive. However, there is a need for development of a
suitable process with lower investments and higher energy recovery. Many distilleries in India are
allowing their effluent for application on land as direct irrigation water, spent wash cake and spent washpress mud compost. The advances manifesting the possibilities of energy conservation are also discernible
in the case of distilleries. The methane gas generated in the digesters is used as a fuel to compensate the
energy needs of the industry. A general estimate suggests that the cost of an anaerobic biological digester is
recovered within 2-3 years of installation because of substantial saving of coal and other fuels.
COST RECOVERY METHODS FROM THE DISTILLERY EFFLUENTS
6.
The wastewaters generated during the distillery and brewery operations contain high organic
loads. It has a BOD from 30,000 to 60,000 mg/1. So due to this high organic contents, the wastewaters can
be subjected to treatment for the production of biogas, composting, aquaculture and potash recovery.
(a)
BIOGAS.
For the production of biogas from distillery effluent, anaerobic
biomethanation of the effluent is adopted, generally. High rate anaerobic technologies are utilized
for biogas generation. Fluidised Bed Reactors and Up flow Anaerobic Sludge Blanket (UASB)
Reactors are mostly utilized for the production of biogas from the effluents. Some of the biogas
production processes being commercial1y established in India at present are:
BIOTHANE PROCESS: This process uses the UASB reactor for the production of
biogas. This is a stable and automatic process with low operational costs.

BIOBED PROCESS: It is similar to Bio thane process. It uses UFB reactors. It needs
less installation area and its construction cost is lower compared to any other system.

BIOPAQ PROCESS: In this process anaerobic bacteria are used to treat the distillery
effluents for the production of biogas. UASB process is utilized here. The separated
sludge in this process makes excellent manure. The generated biogas is used to produce
steam for the distillation of alcohol and thus it replaces 50-60% of the total required
energy in the process of distillation. For a plant having 40-45,000 kg COD/day 75-80%
of COD can be reduced and nearly Rs. 25.50 lakhs can be saved annually for a distillery
having 300 working days in a year. The generated biogas from UASB reactor of BioPaq
process can be collected and be used as a fuel in gas/dual engine. Through suitable
coupling the engine can be coupled with the A/C generator for generation of electricity
from biogas. For a 45 klpd distillery 11 KV of power is generated which is then utilized
in the distillery thus cutting down the power consumption.

SULZER' S PROCESS: The technology of this type of biogas plant is provided by
Sulzer Brothers Limited, Switzerland. It is specifically made for Indian conditions. A
biogas plant at the distillery of Padmashri Dr. Vitthalrao Vikhe Patil S.S.K. Ltd.,
Pravaranagar, Ahmednagar District, Maharashtra is based on Sulzer's technology. The
capacity of this distillery is 6,000 lpd which generates 900 m3 of spent wash per day.
The biogas production is in the range of 16,550 to 21,870 m3 per day. The savings in
the cost of fuel is in the range of Rs. 312 lakhs to Rs. 652 lakhs per year.
o
ECONOMICS OF THE BIOGAS PLANT OF SULZER’S DESIGN
These calculations are made for a distillery producing 30,000 litres of alcohol per
day. The effluent characteristics are for conventional batch type fermentation
process.
o
EFFLUENT CHARACTERISTICS
Flow m3/day
pH
BOD mg/l
COD mg/l
Before Treatment
After Treatment
450
450
4.0 to 4.5
7.0 to 7.8
45,000 to 50,000
6,000 to 8,000
80,000 to 1000,000
25,000 to 35,000
o
PERFORMANCE
Reduction of BOD %
Reduction of COD %
Biogas Production Nm3/day
Specific Biogas Production Nm3/kg of COD degraded
% of methane in biogas
o
80 to 85 %
65 to 70 %
12,300
0.4 to 0.5
60 to 65 %
ECONOMICS
Calorific value of biogas
Calorific Value of Coal
Coal equivalent of Biogas per day
Cost of Coal at Rs 1800 per tonne
Annual fuel savings
Capital cost of plant
Interest at 15 % on 75 % of the capital cost**
Maintenance costs
Staff Salary
Power 40 KW at Rs 2/- per unit
Total Annual Cost
Net Savings per year
Total Pay back period
6000 Kcal/ Nm3
4000 Kcal/Kg
18.45 tonnes
Rs 33,210 pd
Rs 99.63 lacs
Rs 230 lacs
Rs 26,73,750
Rs 2,00,000
Rs 1,50,000
Rs 5,76,000
Rs 36,00,000
Rs 99.36 – 36
= Rs 63.63 lacs
= 230 / 63.63
= 3 to 4 years.
(b) COMPOSTING In this process, press mud generated from sugar mill is utilised to produce
compost by mixing distillery effluent. Both anaerobic and aerobic composting systems are
practiced. In some plants composting with treated effluent treated through bio-methanation plant is
also practiced. This system can achieve zero effluent if the press mud quantity matches with the
effluent generated.

ECONOMICS OF BIOEARTH COMPOSTING
Capacity of the Distillery
Number of working days in a year
In the Distillery
In the Composting Plant
Generated spentwash
Solid content in spentwash
Spentwash to Press mud Ratio
Man Power Required
Culture Requirement
Press mud requirement
Cost of Culture
Cost of Press mud
Man Power cost
Capital Cost
Land Requirement
Bio Earth Production
Annual Maintenance Costs
% Costs of Funds

50 KLPD
300
275
350 KLPD (Biostil Plant)
17 %
2.5 KL : 1 MT
50
31.5 MT/annum
43,000 MT/ annum
Rs 1.75 lakhs per MT
Rs 12 per MT
Rs 50 per day
Rs 175 lakhs (excluding land)
25 acres
38,000 MT per year
1.5 % of equipment costs
20 % per annum
OPERATION COSTS
Cost of Culture
Average Cost of Funds
Cost of Diesel
55.13 lakhs
17.5 lakhs
11.32 lakhs
Cost of Press mud
Cost of Transportation of Press mud
Annual Man Power Cost
Depreciation (@ 10 %)
Maintenance
Annual Operational Cost of Compost Plant
5.16 lakhs
0.00
6.88 lakhs
15.00 lakhs
2.25 lakhs
113.24 lakhs
Cost of One Metric Tonne of Bioearth
=Annual Operational cost of plant
Compost Produced in MT
=
=

NET COST/BENEFIT FOR DIFFERENT SELLING PRICES OF COMPOST
SP of Bioearth
in Rs
Net Cost / Benefit
in Rs
0
100.00
200.00
298.00
350.00
400.00
500.00
-11324000.00
-7524000.00
-3724000.00
0.00
1976000.00
3876000.00
7676000.00
Net annual cost/benefit of Compost

11324000
38000
Rs 298.00 per MT
=
Sales value of 38000 MT of
compost less annual operating costs
COMPUTATION OF PAY BACK PERIOD
1.
SP of Bioearth
Initial cash outflow
Net annual cash inflow
Pay Back Period
-
Rs 250.00
Rs 17500000.00
Rs 1738000.00
10.06 Years (17500000/1738000.00)
2.
SP of Bioearth
Initial cash outflow
Net annual cash inflow
Pay Back Period
-
Rs 350.00
Rs 17500000.00
Rs 5226000.00
3.34 Years (17500000.00/5226000.00)
3.
SP of Bioearth
Initial cash outflow
Net annual cash inflow
Pay Back Period
-
Rs 500.00
Rs 17500000.00
Rs 10926000.00
1.6 Years (17500000.00/10926000.00)
(c)
POTASH RECOVERY It is done by incinerating the distillery spent wash. In this
process, the raw distillery spent wash is first neutralized with lime and filtered. This is further
concentrated to about 60% solids in multiple-effect forcer circulation evaporators. Now this thick
liquor from the evaporator is burnt in an incinerator and is converted into ash. The dry solids of
the spent wash in the form of coke in the incinerator has an average calorific value of 2 Kcal/kg,
which is sufficient for supporting self-combustion of the thick liquor in the incinerator. The
resulting ash is found to contain about 37% of potash as potassium oxide on an average. This ash
is further leached with water to dissolve the potassium salts. Then it is neutralized with sulphuric
acid and is evaporated. The potassium salts are crystallized in a crystal1izer. The crystallized
mixed potassium salt contains 73.5% of potassium sulphate (K 2SO4) 16.5% potassium chloride
(KCl) and 5% of sodium salts. It is estimated that a distillery discharging about 300 m3 of spent
wash per day could recover 3 tonnes of Potassium as Potassium oxide or about 5.34 tonnes of
Potassium sulphate and 1.2 tonnes of Potassium chloride per day. This potassium is used as a
fertilizer.
(d)
DISTILLERY WASTEWATER UTILISATION IN AGRICULTURE Being very
rich in organic matters, the utilisation of distil lery effluents in agricultural fields creates organic
fertilization in the soil which raises the pH of the soil, increases availability of certain nutrients
and capability to retain water and also improves the physical structure of soil. Mostly the distillery
wastewaters are used for pre-sowing irrigation. The post-harvest fields are filled with distillery
effluents. After 15-20 days, when the surface is almost dried, the fields are tilled and the crops are
sown and subsequent irrigation is given with fresh water. However, the effluent is diluted 2-3
times before application on crops. Apparently, the irrigation with distillery wastewater seems to be an
attractive agricultural practice which not only augments crop yield but also provides a plausible solution
for the land disposal of the effluents. One cubic metre of methanated effluent contains nearly 5 kg of
potassium, 300 grams of nitrogen and 20 grams of phosphorus. If one centimetre of post methanation
effluent is applied on one hectare of agricultural land annually, it will yield nearly 600 kg of potassium,
360 kg of calcium, 100 kg of sulphates, 28 kg of nitrogen and 2 kg of phosphates. The distillery effluent
contains 0.6 to 21.5 percent potash as K O , 0.1 to 1.0 percent phosphorus as PO and 0.01 to 1.5 percent
Nitrogen as N2. The irrigational and manorial potential of distillery wastewaters is given below:

i)
Total Volume available in Million m3 /annum
:
6.87
ii)
Nutrients Contribution Potential (tonnes/annum)
:N
PO
KO
-
69380
11335
27480
ECONOMICAL ASPECTS
When the distillery effluents are used for i r r i g a t i o n in fallow lands, the microbes present
in it transform the lands into fertile ones, giving high yields of paddy and sugarcane.
Farmers could save nitrogenous fertilisers worth Rs 1335 crores per annum if at least 200
distilleries of out country recycled their wastes to the agricultural fields. However, it is
predicted that the utilisatio n of distillery effluent for irrigation of land would make a v a i l able nitrogen, phosphorous and potash valued at about Rs 500 crores each year. The added
advantage of this application would be that these fertilisers would be a v a i l a b l e to s o i l in
organic form. As the secondary and tertiary systems for the treatment of distillery effluent are
highly energy intensive and according to the estimates of the Union Ministry of Energy a total
connected load of 200 M.W. would be required to energising these systems if 246 distilleries
endeavour to reduce the BOD level of effluent to the extent possible. The generation of the
desired energy would need an installed load of 350 M.W. which would require capital
investment of the order of about Rs 1400 crores. So it will be an attractive practice to utilise the
distillery effluents for ferti-irrigation of land after primary treatment, as land is available in
abundance around the distilleries which are located in the sugarcane belts.
RECOMMENDATIONS
7.
Reviewing the magnitude of pollution potential of distillery wastewaters and the experiences gained over
years on recovery of residues and treatment of wastewater the following recommendations are made : In-plant control measures for conservation and reuse of water and good house-keeping for prevention
of spillage and leakages should be the prerequisite.
 For recovery from the treatment of distillery spentwash, depending on the availability and cost of
land in a particular area, simple treatment in anaerobic lagoon to generate biogas followed by treatment in
aerated lagoon or oxidation ditch may be considered. Where the availability and cost of land are the main
constraints, activated sludge type of aeration treatment in a deep oxidation ditch would be more
economical than the conventional or extended aeration sludge process.
 For the treatment of distillery spent wash, removal and/or recovery of yeast should be prerequisite to
reduce the load and eliminate certain undue problems in the waste treatment/recovery plants. This
recovered yeast can be utilised as a good cattle feed. Recovery of spent grains and yeast and their
utilisation as animal feed and feed supplement might be encouraged not only for reducing the pollution
load form the wastewaters but also in providing for a reasonable return on their capital investment of the
industry.
 Where the availability of land is a severe constraint, evaporation and incineration of distillery spent
wash to recover potash would appear to be the only choice. In spite of high capital investment required for
such type of plants, heat recovery would defray significantly the organisation and maintenance costs and
contribute towards conservation of energy.
 In the countries like ours, where indigenous sources of potash are scarce or not available, recovery of
potash from crude ash by evaporation and incineration of spent wash would appear to be an economically
attractive alternative. If heat recovery is simultaneously used, the pay back period of the plant can be
substantially reduced.
 Anaerobic digestion of spent wash in a closed digester followed by its treatment under an activated
sludge process, especially in an oxidation ditch to reduce costs, might be adopted as the most costeffective system for the distilleries which are located away from sugar factories. Moreover, the treated
effluent can be conveniently used for irrigation of cane fields or other crop lands, subsequently.
 Biogas generated from the distillery effluents, can be effectively utilized in production plant boilers
thus saving about 50 to 60 percent fuel/steam. The treated effluent having almost all the potash retained in
it may be utilised for irrigation purposes.
 The utilisation of the distillery effluent in agricultural fields will not only enrich these further with
essential plant nutrients like nitrogen, phosphorous and potash but also compensate the expenditure on
fertilizers for crop growth. This practice will result in revenue generation and further lead to offsetting the
costs substantially.
 Similarly spentwash utilization in bioearth composting, where adequate land is available, being a
simple process and not involving any heavy machinery is also one of the cost effective methods of
disposal. Moreover it is feasible alternative for utilization of treated effluent; as the same generates
revenue thus offsetting the costs and further leading to reduction in pay back period.
CONCLUSION
8.
One of the most important environmental problems faced by the world is management of wastes.
Now-a-days emphasis is laid on waste minimization and revenue generation through byproduct recovery.
Pollution prevention focuses on preventing the generation of wastes, while waste minimization refers to
reducing the volume or toxicity of hazardous wastes by water recycling and reuse, and process
modifications and the byproduct recovery as a fall out of manufacturing process creates ample scope for
revenue generation thereby offsetting the costs substantially.
9.
The cost of effluent treatment in distilleries is likely to be compensated substantially by
availability of methane gas. Effluent application will reduce the nutrient requirement through fertilisers.
However, high salt load, mainly potassium and sulphur, into the soil system may hamper the sustained crop
yields due to continued long-term application of effluents. Therefore the effect on crop productivity has to
be visualised on long-term and sustainable basis. Application of post methanation effluent suitably diluted
according to crop requirements and soil conditions seems to be viable alternative. If all the distilleries
present in India resort to biomethanation, then approximately 2.0 million cubic metres of biogas shall be generated
per day, with a calorific value of approximately 5000 Kcal/m. This is equivalent to saving of 2240 tonnes of
coal per day, in turn avoiding CO of about 3100 tonnes per d ay.
10.
The present study coupled with the corresponding techno market survey has been aimed at
reviewing the existing technological status of treatment and disposal of distillery spentwash in our country
and comparing with that of the contemporary international technologies, thus identifying the gaps in the
technologies and suggesting an action plan for overcoming these. Some relative issues in the areas of
quality criteria with respect to gaps in technologies and financial implication in implementing the
technological options, has been highlighted in this study. It has to be stressed that recovery from the
distillery effluents is a better way to reduce the cost of wastewater treatment for decreasing its pollution
level which is actually a very costly affair. So this is a matter great importance for the Indian distilleries
and breweries. Various recommendations are given for the establishment of recovery plants in India. It has
also been elucidated during the study that several technological options that are available in our country
need to be exploited to the maximum so that, this will help to control the pollution created by the distillery
wastewaters and also enable to derive by-products which are commercially beneficial.
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