Charter

for
Zero Liquid Discharge (ZLD) in
Molasses Based Distilleries

Central Pollution Control Board

Contents
1.0 Introduction ......................................................................................................................................... 4
2.0 Quality of Molasses in North India .............................................................................................. 5
3.0 Quality of Indian molasses ............................................................................................................. 6
4.0 Manufacturing Process of Alcohol ................................................................................................ 6
5.0 Problem analysis and Spent wash characteristics ................................................................. 8
6.0 Review of practices of ferti-irrigation and pre-sown irrigation (one-time land
application): ....................................................................................................................................... 11
7.0 Objectives of the Charter implementation programme ..................................................... 15
8.0 Proposed Strategy with holistic approach .............................................................................. 17
9.0 Benchmarking of process technology vis-a-vis spent wash generation norms ....... 18
10.0 Water Consumption in Molasses based Distilleries ............................................................. 21
11.0 Guidelines for Molasses based Distilleries .............................................................................. 22
12.0 Available Effluent Treatment routes for achieving ZLD ..................................................... 24
13.0 Best Available Technologies ......................................................................................................... 29
13.1 Yeast Propagation ............................................................................................................................ 29
13.2 Fermentation ..................................................................................................................................... 29
13.3 Fermentation with spent wash recycle .................................................................................... 30
13.4 Distillation ........................................................................................................................................... 30
14.0 Distillery Effluent Treatment Technologies ............................................................................ 31
14.1 Bio-methanation ............................................................................................................................... 31
14.2 Reverse osmosis (RO) .................................................................................................................... 32
14.3 Multiple Effects Evaporators (MEE) ........................................................................................... 32
14.4 Bio-composting ................................................................................................................................. 33
14.5 Incineration of distillery spent wash ......................................................................................... 33
14.6 Drying of Spent wash ..................................................................................................................... 33
14.7 Condensate Polishing Unit (CPU) Technologies .................................................................... 34
15.0 Performance Norms and Output Conditions for Effluent Treatment Technologies . 35
15.1 Biomethanation................................................................................................................................. 35
15.2 Reverse osmosis............................................................................................................................... 35
15.3 Multiple-effect evaporation (MEE) of distillery spent wash .............................................. 36
15.4 Bio-composting ................................................................................................................................. 37
15.5 Incineration of spent wash ........................................................................................................... 37
15.6 Dryers for spent wash drying ...................................................................................................... 38
15.7 Technology for Recovery of FCO grade Potash Fertilizer and potash free
organics/de-potash vinasse (DPV) from Molasses-based Distillery Spent Wash . 38
15.8 Condensate polishing unit ............................................................................................................ 39
16.0 Prescribed Standards to be adopted by Molasses based Distilleries ............................ 40

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17.0 Annexure-I: Standard Operating Procedure (SOP) for Bio-composting operation
for Molasses based distilleries ..................................................................................................... 43
17.1 Specification of covered Bio-compost yard for Distillery operating throughout year
............................................................................................................................................................. 45
17.2 Specification of Bio-compost yard for Distillery operating 270 days(excluding rainy
season) ............................................................................................................................................. 47
18.0 Bio-compost area calculation:..................................................................................................... 49
19.0 Standard Operating Procedure (SOP) for Incineration boiler operation
for Molasses based distilleries.............................................................................................. 50

List of Tables

Table 1: Characteristics of sugarcane juice, B heavy molasses and C heavy molasses ...... 5
Table 2: Raw spent wash characteristics from C heavy molasses ................................................ 9
Table 3: Raw spent wash characteristics generated from different feedstock ......................... 9
Table 4: Typical Characteristics of Bio-methanated spent wash from C heavy molasses . 10
Table 5: Standards notified by MoEF vide GSR 176(E), April 02, 1996 for fermentation
industry ............................................................................................................................................. 17
Table 6: Comparison of different fermentation systems using C heavy molasses ............... 19
Table 7: Comparison between atmospheric and MPR distillation systems .............................. 20
Table 8: Process technology and corresponding specific fresh water consumption and
specific spent wash generation ................................................................................................ 21
Table 9: Biomethanation performance efficiencies ........................................................................... 35
Table 10: Reverse Osmosis Performance Parameters ..................................................................... 36
Table 11: Combined raw spent wash process condensate plus spent lees and treated
water characteristics ................................................................................................................. 39

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1.0 Introduction

India is the largest sugar consumer and second largest producer of sugar and
molasses. It is also the fourth largest producer of alcohol in the world while being the
leading producer of alcohol in the South-East Asian region with about 65% of the total
share. The major raw material for distilleries is molasses, a waste byproduct of sugar
mills and grains. Sugarcane, the raw material for sugar mills, is one of the major crops
of the country. Consequently, agricultural and rural economy is significantly dependent
on sugarcane farming and associated industries. Besides, sugar mills, distilleries and
associated industries also provide large employment potential and contribute
substantially to economic development of the country. As per Indian Sugar Mills
Association (ISMA), in 2018-19, the total estimated revenue realization from sugar and
byproducts was 1 lakh crore of which 81% was contributed by Sugar Industry while
distilleries contributed 13% and other byproducts contributed remaining 6%. It is
apparently the 2nd largest revenue contributor per annum for the government.

Molasses, a byproduct of sugar industries is the major raw material for distilleries in
India while a few distilleries also use grains such as sorghum, corn, rice, wheat, millet
etc., as raw material. Since sugar season 2019-20, Government of India (GOI) has
allowed use of either sugarcane juice, sugarcane syrup, B Heavy molasses or sugar as
feedstock for ethanol production, apart from the conventional C heavy molasses. As
compared to ethanol derived from C- heavy molasses route, diversion of B heavy
molasses reduces the sugar availability by 15-20 % and increases ethanol availability by
about 90-100%. On the other hand, diversion of sugarcane juice for ethanol production
reduces sugar availability by 100% and increases ethanol availability by about 580-
600%. Due to consistent surplus in sugar production and resulting depression in sugar
price, diversion of sugar cane juice and B heavy molasses in ethanol production can boost
both the ethanol economy as well as revive the sugar industry.

As per All India Distillers Association (AIDA), in 2019-20, there were 392 molasses
based distilleries and 113 grain based distilleries in the country with total installed
capacity of 6.93 billion litres per annum and 2.58 billion litres per annum respectively.
In India, distilleries are classified as “Red Category” since molasses based distilleries
consume significant quantities of fresh water and produce spent wash (vinasse) having
very high pollution load.

In India alcohol is produced in the form of either i) Rectified Spirit (95 to 96 % v/v
ethanol) that is mainly utilized for industrial purposes in the form of ordinary and special
denatured spirit (ODS or SDS), ii) Extra Neutral Alcohol or Neutral Spirit (96 % v/v

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ethanol that is used for manufacture of potable liquors and iii) Fuel Ethanol or Anhydrous
Alcohol that is mainly used for blending with petrol.

The average capacities of Indian molasses based distilleries ranges between 30 to

60 KLPD. There are very few distilleries above 100 KLPD capacities as well. However,
with aggressive implementation of Ethanol Blending Programme (EBP) by GOI, the
capacities of Indian distilleries are now gradually increasing.

2.0 Quality of Molasses in North India

Molasses, a byproduct of sugar manufacturing from sugar-cane, is the main raw material
for distilleries. The molasses (final or C molasses) produced from sugar mills in Uttar
Pradesh and its neighboring states ranges between 4.0 to 5.25 % of the sugar-cane
crushed. The B Heavy molasses is ranging in between 6.0 to 7.0 % of sugar-cane crushed.
The typical characteristics of C heavy molasses, sugarcane juice and B heavy molasses
available in Uttar Pradesh and its neighbouring states is given in Table 1.

The quality of Indian C heavy molasses is inferior as compared to the molasses available
in countries such as Brazil and Australia and also varies widely within the country. The
reason for inferior quality of molasses is manufacture of sugar by double sulphitation
method that involves three and half boiling and use of SO2 for sulphitation. However, the
quality of B Heavy molasses is superior as compared to C molasses in terms of its
fermentability. Yield of ethanol from final/ C heavy molasses is 235 litres/Ton while it is
310 litres/Ton from B heavy molasses.

Table 1: Characteristics of sugarcane juice, B heavy molasses and C heavy

molasses

S. N. Parameters C Molasses BH Molasses Cane syrup

1 pH 5.01 5.41 4.74
2 oBrix 88.0 86.0 57.00
3 Total Reducing Sugars % 50.08 61.00 52.58
4 Unfermentable Sugars % 5.01 2.60 0.67
5 Fermentable Sugars % 45.07 58.40 51.91
6 Carbonated ash % 10.0 9.8 1.0
7 Sulphated ash % 13.0 11.5 2.5
8 F/N 1.05 2.2 6.4
9 Volatiles acidity (ppm) 5000 2000 1000
10 Sp. Gravity 1.40 1.35 1.19
11 Total microbial count (CFU/gram) 5.6 103 8.8 101 7.5 101
12 Shelf life 1-2 years 1-2 years Perishable

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3.0 Quality of Indian molasses

As far as Indian molasses is concerned the quality of molasses is usually judged on

the basis of following:
i. Fermentable to Non-fermentable (F/NF) ratio: This should be as high as
possible but not less than 1
ii. Level of contaminants in molasses: The average contamination level in
molasses is about 103 CFU/g of molasses. Higher level than this results in poor
fermentation of molasses. (here, CFU/g- Colony Forming Unit per gm)
iii. Total Organic Volatile Acidity (TOVA) of molasses: For good quality molasses
the TOVA should be in the range of 3000-3500 ppm. Higher volatile acidity is an
indication of contamination of the molasses and the volatile acids generated retards
the fermentation rates.
iv. Sludge content of molasses: The normal range of sludge content of molasses is
8.0-12.0% (v/v). Higher sludge content results in lowering the effective volume of
fermenters and scaling problems in equipment and distillation columns.

4.0 Manufacturing Process of Alcohol

Production of alcohol comprises broadly of three sections, viz. (i) Fermentation (ii)
Distillation and (iii) Effluent treatment and disposal.
(i) Fermentation: Alcoholic fermentation is the process in which sucrose and reducing
sugars (i.e. glucose and fructose) present in molasses/sugarcane syrup are converted
into ethyl alcohol and carbon dioxide by the action of several enzymes present in
yeast.
(ii) Distillation: It is a purification step wherein the fermentation wash generated in the
fermentation section, is subjected to heat in the analyzer column to separate alcohol
from the wash on the basis of difference in boiling points. The alcohol is further
subjected to purification in the pre rectifier and rectifier columns to obtain rectified
spirit (95% v/v).
(iii) Effluent treatment: The effluent generated from analyzer column after distillation of
alcohol is known as spent wash while further purification of alcohol in pre rectifier and
rectifier columns results in generation of weak effluent known as spent lees. Treatment
of spent wash and spent lees is the last step in the production of alcohol.

Typical alcohol manufacturing process from molasses is illustrated in Fig 1 while

manufacturing process from sugarcane juice is illustrated in process flow diagram given in
Fig 2.

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Figure 1: Typical process flow diagram for alcohol production from molasses ‘

MOLASSES WATER

DILUTER YEAST PROPAGATION

SECTION
FERMENTER

FERMENTER SLUDGE

ANALYZER SPENT
STEAM
WASH

RECTIFIER SPENT
LEES
ALCOHOL
SPIRIT RECEIVERS EFFLUENT
AND STORAGE SECTION TREATMENT

Figure 2: Process flow diagram for alcohol production from sugarcane juice

SUGARCANE

CLEANING

EXTRACTION OF SUGARCANE
SUGARS BAGASSE

JUICE TREATMENT
CLARIFIED JUICE

JUICE CONCENTRATION

JUICE STERILIZATION

FERMENTATION ANALYSER COLUMN SPENT WASH

Yeast

CENTRIFUGATION DISTILLATION & SPENT LEES

RECTIFICATION

YEAST ANHYDROUS
DEHYDRATION
TREATMENT ALCOHOL
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5.0 Problem analysis and Spent wash characteristics

Depending on the quality of molasses used, technology adopted for fermentation

and distillation system employed, the raw spent wash generation (before concentration)
can vary between 8.0 liters to 16.0 liters for every liter of alcohol produced. The general
characteristics of spent wash generated by different fermentation techniques is given in
Table 2. Comparative characteristics of spent wash generated from different feedstock in
fed-batch fermentation is given in Table 3.
Spent wash management is a challenge as disposal of the large volume of bio-
methanated spent wash and /or raw spent wash (on average 10-12 KL/KL of alcohol in
case of C heavy molasses) having high Chemical Oxygen Demand (COD) & Biochemical
Oxygen Demand (BOD) and salt load is a serious concern for the distilleries. Pollution
control authorities in the country have stipulated stringent norms for proper disposal of
spent wash as its uncontrolled discharge may affect the land surfaces and water bodies,
particularly the physical, chemical and biological properties of soil and water.
The enforcement of norms for effluent treatment and discharge in Indian distilleries
is to achieve fresh water conservation and prevention of pollution while taking into
consideration the limited availability of land for disposal as compared to the norms followed
in other countries.
Distillery spent wash has very high BOD, COD and high BOD/COD ratio. The amount
of inorganic substances such as chlorides, sulphates, phosphates, potassium and calcium
are also very high. Its recalcitrant nature is due to the presence of melanoidins, caramel,
polyphenols and variety of sugar decomposition products such as anthocyanins, tannins
and different xenobiotics compounds. The unpleasant odour of the effluent is due to the
presence of skatole, indole and other sulphur compounds, which are not effectively
decomposed during fermentation and distillation. Melanoidins are formed by Millard amino
carbonyl reaction and have antioxidant properties, which make them toxic to many
microorganisms. High COD, total nitrogen and phosphate content of spent wash can result
in eutrophication of natural water bodies. The highly coloured compounds of the spent
wash reduces sunlight penetration in water bodies, which in turn decreases both
photosynthetic activity and dissolved oxygen concentration thereby affecting aquatic life.
Uncontrolled or random application of distillery spent wash on land is hazardous to
the vegetation. It is reported to reduce soil alkalinity and manganese availability, thus
inhibiting seed germination. Use of bio-methanated spent wash for irrigation without
proper monitoring can affect the groundwater quality by altering its physicochemical
properties such as colour, pH, electrical conductivity etc. due to leaching of the organic
and inorganic ions.
The huge mass of effluent with highly objectionable organic matter renders the
spent wash from distilleries unfit for direct discharge on land, irrigation as well as discharge

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into rivers or streams. Decomposition of spent wash emits very bad smell causing
atmospheric pollution. Therefore, proper treatment of this effluent is necessary.

Table 2: Raw spent wash characteristics from C heavy molasses

Sr.No. Parameter Batch process Cascade Biostil process
process
1 Volume, L/L Alcohol 14-16 10-12 8-10
2 Colour Dark brown Dark brown Dark brown
3 pH 3.7-4.5 4.0-4.3 4.0-4.2
4 COD 80,000- 1,10,000- 1,40,000-
1,10,000 1,30,000 1,60,000
5 BOD 45,000-50,000 55,000-65,000 60,000-70,000
6 Total Solids 90,000- 1,30,000- 1,60,000-
1,20,000 1,60,000 2,10,000
Total Volatile 60,000-70,000 60,000-75,000 80,000-90,000
Inorganic dissolved 30,000-40,000 35,000-45,000 60,000-90,000
7 Chlorides 5,000-6,000 6,000-7,500 10,000-12,000
8 Sulphates 4,000-8,000 4,500-8,500 8,000-10,000
9 Total nitrogen 1,000-1,200 1,000-1,400 2,000-2,500
10 Potassium 8,000-12,000 10,000-14,000 20,000-22,000
11 Phosphorus 200-300 300-500 1,600-2,000
12 Sodium 400-600 1,400-1,500 1,200-1,500
13 Calcium 2,000-3,500 4,500-6,000 5,000-6,500
Note: All values from S. No. 4 -13 are in mg/l.

Table 3: Raw spent wash characteristics generated from different feedstock

Cane syrup
S. N. Parameters C Molasses BH Molasses Cane syrup
After recycle
1 pH 4.0 4.2 4.5 4.5
2 Color Dark Brown Yellowish brown Pale Yellow Pale Yellow
3 Quantity (L/L alcohol) 10 8 6 3
4 oBrix 12 8 2.5 4.5
5 COD (mg/L) 120000 80000 25000 45000
6 BOD (mg/L) 60000 40000 12000 22000
7 Dissolved solids (mg/L) 60000 50000 18000 24000
Suspended solids
8 30000 20000 3000 6000
(mg/L)
9 Total solids (mg/L) 90000 70000 21000 30000
10 Nitrogen (mg/L) 1000 700 400 600
11 Phosphorus (mg/L) 300 200 100 150
12 Potassium (mg/L) 10000 4000 1000 1500

Although several technologies have been introduced for treatment of raw spent
wash generated by distilleries, these include various biological treatments (anaerobic and
aerobic), controlled land application, physicochemical and thermal treatments among
others; the capital and recurring cost involved in the treatment of huge quantity of

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distillery spent wash to comply with stipulated standards is often equal to or higher than
the cost of the distillery plant itself. Therefore, there has been a shift from end of pipe
treatment to an integrated waste management comprising of control of manufacturing
process, solid waste management and recovery from waste.
Anaerobic digestion/bio-methanation is a commonly used primary treatment
method for spent wash generated from molasses based distilleries in India. The
characteristics of bio-methanated spent wash in case of C heavy molasses are given in
Table 4. However, even after bio-methanation, the COD and BOD levels are quite high and
the colour is dark brown/blackish thereby indicating that it is not possible to dispose this
primary treated spent wash though drains or through uncontrolled or indiscriminate land
application. The bio-methanated spent wash generated from use of B-Heavy molasses or
sugarcane syrup will have relatively lower COD, BOD and total solids as compared to spent
wash generated from use of C heavy molasses. Irrespective of the type of raw material
used, it is necessary to adopt an all-encompassing, environment friendly and economically
viable treatment system/s for bio-methanated/raw spent wash.
Table 4: Typical Characteristics of Bio-methanated spent wash from C heavy
molasses

Sr. No. Parameters Bio-methanated spent

wash
1 pH 7.0-7.5
2 COD 25000-35000
3 BOD 5000-8000
4 Total solids 35000-40000
5 Total volatile solids 6000-7500
6 Inorganic dissolved 25000-35000
7 Chlorides 5000-6000
8 Sulfates 2000-5000
9 Total nitrogen 1000-1200(1.0 kg/m3)
10 Potassium 8000-10000 (9 kg/m3)
11 Phosphorus 800-1200 (0.8 kg/m3)
12 Sodium 600-1200(1.0 kg/m3)
13 Calcium 4000-5000(4.5 kg/m3)
Note: All the values in mg/l except for volume and pH.

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6.0 Review of practices of ferti-irrigation and pre-sown irrigation
(one-time land application):

In 2003, CPCB issued charter on Corporate Responsibility for Environmental

Protection (CREP) for the existing molasses based distilleries wherein five technologies,
namely ferti-irrigation, one time land application (pre-sown irrigation application), bio-
composting practices, concentration-incineration system and controlled discharge of pre-
treated spent wash into deep sea, were identified for spent wash management so as to
minimize the impacts on recipient environment and distillery units were asked to comply
with any one or any combination of the five technologies within a period of three years.

Performance of distilleries practicing ferti-irrigation, one-time land application (pre-sown

irrigation), and bio-composting was assessed by CPCB on the basis of inspections
undertaken for a period of five years from 2006-2011 under the ESS programme and
major findings are summarized as follows:
- Of 111 distilleries inspected during the period 2006-2011, significant/serious
violations were observed in 70 distilleries (63% non-compliance).
- General treatment practice recommended for distilleries adopting ferti-irrigation or
one-time land application was bio-methanation followed by primary clarifier, two-
stage extended aeration system, secondary clarifier, sludge drying beds followed by
storage of partially treated effluent in lined/ unlined lagoons for ferti-irrigation/one-
time land application. However, most distilleries were found to undertake only
biomethanation.
- As per guidelines, for ferti-irrigation and pre-sown irrigation, the recommended BOD
level in treated spent wash was 800 mg/l and 7000 mg/l respectively. However,
inspection reports indicated use of spent wash with BOD > 20000 mg/l, COD ≥
80000 mg/l for land application. In case of pre sown irrigation, often raw spent wash
was found to be used.
- Due to the high organic load of spent wash, dilution of up to 12-20 times was
required to meet the critical water quality parameters thereby resulting in huge
consumption of fresh water.
- Based on the quantity of spent wash generated and dilution to meet the nutrient
requirements of the crops, land area of 20-25 ha/KL alcohol production was required
to match the spent wash disposal.
- Recommended command area for ferti-irrigation was radial distance of 20km but
most distilleries were found to have only few hectares of land and the available land
was scattered over large distances making monitoring and effective control over the
practice almost impossible.
- As per guidelines, nitrogen level in spent wash has to be adjusted before application

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 in accordance to the nitrogen requirement of the crop and soil type. Also, spent wash
to be applied on alternate years. However, this resulted in practical problems such
has high dilution levels, huge land requirement, one to two irrigations to achieve
desired nitrogen level, huge accumulation of spent wash in lagoons ultimately
leading to indiscriminate discharge on land and surface water.
- There was found to be zero compliance to the requirement of distribution networks
of impervious conduits, impervious liner system etc., thereby leading to leaching
and ground water contamination.
- Effluent flow through earthen channels was not permitted but all distilleries were
found to distribute spent wash only through earthen channels.
- The incidences of spent wash disposal along with storm water into nearby water
bodies through bypass pipelines/drains were also reported.
- Ground water samples were found contaminated having colour, high TDS, nitrate
and conductivity.
- As per guidelines, distilleries were permitted to have lagoon capacity equivalent to
one fourth of average yearly utilization of spent wash, but almost all distilleries were
found to store huge quantity of spent wash in lined and unlined lagoons. The main
reason for accumulation of spent wash was the high dilution factor required to meet
the nutrient requirements.
- For pre sown irrigation practice, it was recommended that maximum of one third of
the spent wash generated per year would be utilised for pre-sown irrigation, instead,
in practice, 50-60% of the total generated spent wash was disposed through
irrigation.
- Distilleries adopting pre sown irrigation practice for spent wash management were
to undertake monitoring of physico-chemical parameters of irrigated land two times
in a year but none of the distilleries were found complying with the same. Instead
inspection teams reported ground water contamination as well as increase in EC
values of the soil after application of spent wash and subsequent reduction with crop
growth which implied leaching.
- Report indicated that there was little or no compliance to the guidelines issued in
CREP for distilleries adopting pre sown irrigation practice.
- There was no compliance w.r.t submission of application by distilleries to SPCB and
record keeping of the transit by vehicles used for transporting spent wash for
irrigation. This resulted in indiscriminate disposal of raw spent wash on land and
surface water.
As per the guidelines for pre sown irrigation practice, application of spent wash should be
on the basis of nitrogen requirement of crops, soil type as per the advice of experts from
agricultural institutions. Also, application to be done at least 30 days in advance of sowing

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and onset of rains and nitrogen requirement of the crop to be applied in a single dose.
However, compliance to these guidelines required huge land area to match the disposal
of spent wash and led to accumulation of huge quantity of spent wash in lined and unlined
lagoons. Also, one irrigation required to achieve the nitrogen requirement hence further
irrigations carried out with only fresh water.
- Studies carried out by various agriculture universities found that pre sown irrigation
led to a. accumulation of salts in the soil and subsequent leaching over time; b.
decrease in soil alkalinity over a long period of time.
- Guidelines w.r.t monitoring of irrigation practices, included analysis of spent wash
stored in lagoons every 15 days; monitoring of physico-chemical characteristics of
soil two times in a year with one representative sample to be collected per 50 ha, at
30 and 60 cm depths; EC of saturation extract of the soil sample not to be allowed
to increase beyond 4.0 mmhos/cm and 20% increase in EC above the background
level should be a matter of concern; pH of the extract should be less than 8.5 and
exchangeable sodium percentage should not exceed 15. However, in practice there
was zero compliance to the aforementioned guidelines. No monitoring was carried
out due to practical constraints such as for soil samples ≥10000 samples were
required to be analysed per year.
- As per guidelines, ground water quality was to be monitored two times in a year (pre
&post monsoon) at one station per 50 ha in the command area. No monitoring
carried out since more than 2500 sampling locations were needed. Moreover, even
scientific studies undertaken by agriculture institutes did not cover ground water
quality.
- Guidelines suggested that values of BOD and Nitrate-N in ground water should not
exceed 3 mg/L and 10 mg/L, respectively. Value of TDS should not increase by 20%
of the background value subject to a maximum increase of 150 mg/L. In practice,
CPCB inspection teams reported wide scale ground water contamination with colour,
high nitrate, high TDS and conductivity.

Additionally, guidelines suggested setting up of at least five soil and water quality monitoring
control stations in areas where spent wash irrigation was not practiced and sampling from
these stations would be carried out every six months. In the event of first observation of
contamination, the effluent application to be stopped immediately and the distillery would
inform the SPCB accordingly. The concerned distillery shall be solely responsible for
reclaiming the soil and water quality at their cost and make good any damage. Alternate
drinking water supply to be provided in the affected area by the distillery. Again in reality
there was zero compliance and although environmental contamination was reported from
many places. Distilleries did not have resources for remediation programme.

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 - Distilleries adopting irrigation practices were directed to install five hand pumps, about
50 m from the storage tanks, encircling the entire area of the tanks, for collection of
samples, every six months. None of the distilleries were found complying.
- As per the irrigation management plan, spent wash shall not be utilized for irrigation
during rainy season and sowing period. Also, in areas where the rainfall is between
100 and 200 cm/year, irrigation may be required only during the dry spells of the rainy
season while ferti-irrigation may be carried out in rainy season in areas where the
rainfall is less than 100 cm/year. Thus, spent wash irrigation could be carried out only
for six months per year.
- For distilleries operating throughout the year, spent wash management through ferti-
irrigation and pre sown irrigation, were found inadequate to match with the spent wash
generation.

In the 147th meeting of the Central Board held on 23rd May,2008, the following observations
were made:

1. Composting, ferti-irrigation and one-time land application cannot be performed

during rainy season. Thus, in rainy season, distilleries had to stop these spent wash
management options as well as alcohol production in rainy season. However, in
practice distilleries continued with production and land application even during rainy
season leading to large scale surface runoff.
2. The distilleries extract huge volume of ground water for dilution of the treated effluent
to meet the requirements of prescribed standards for ferti-irrigation and one- time
land application, which is not an environmentally sound practice and against policy
of water conservation.
3. For ferti-irrigation, large amount of land (9 Ha per KL of alcohol) is required. Since
industries themselves don’t have access to such large area, they partner with local
farmers. However, it is practically impossible to monitor and control such large land
area scattered in the radial area of ≥20 km.
4. The practices of ferti-irrigation and one-time land application resulted in
accumulation of huge quantity of spent wash in lined and unlined lagoons.
5. Indiscriminate disposal of untreated SW on land/ frequent discharge into surface
water bodies.
6. Instances of environmental damage have been reported from Uttar Pradesh, Punjab,
Tamil Nadu and Karnataka due to violation relating to these practices.
7. Studies by the agriculture universities were unable to establish that the decrease in
available organic/ inorganic soil contents with time is due to uptake by crop only.
8. Most of the studies were aimed to assess manorial value and lacked proper ground
water quality impact assessment/leachability study of the soil mixed with spent

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 wash.

• Based on these observations, the Board considered and approved the following
recommendations which were forwarded to MoEF&CC vide letter dated 04.06.2008:
a. Although it is likely that these effluents due to their nutrient composition may
facilitate better yields in the beginning but continued and indiscriminate use can
lead to salt accumulation in the soil, endangering its productivity and
sustainability. Subsequent leaching with time leads to groundwater
contamination.
b. Chloride and sulphide concentration is high is spent wash and these compounds
pose serious threat to soil environment under long term use. Therefore, it
becomes essential to undertake detailed investigation into the dynamics of high
salt load in the soil, groundwater and atmosphere continuum system.
c. According to recent research, distillery effluent released on soil surface,
contaminate ground water. Due to high salt contents, spent wash retard seed
germination and plant growth.

• Thus, under these circumstances, in 2008, the Central Board resolved that distilleries
not complying with the required environmental standards may be asked to switch over
to emerging technologies from existing practices of composting, ferti-irrigation and one
time land application of spent wash in a time bound manner and shall achieve zero liquid
discharge.
• Zero Liquid Discharge was implemented in the distilleries operating in Ganga main stem
vide CPCB direction dated 07.12.2015 issued under Section (18) (1)(b).

7.0 Objectives of the Charter implementation programme

The implementation of a validated action plan by industrial units discharging their effluent
into River Ganga and its tributaries is considered an effective measure for prevention and
control of industrial pollution. Industrial effluent discharge is a major contributor to
pollution in River Ganga and in this regard, distilleries have been identified as one of the
main sectors contributing to industrial pollution in River Ganga.
The generation of large volume of spent wash with high pollution load by the distilleries
has led the pollution control authorities in India to initiate the implementation of strict
environmental norms including zero liquid discharge of process and non-process effluents
from distilleries.

CPCB has taken initiative to assess the effluent treatment plant performance and
achievement of the prescribed norms by distilleries in the Ganga basin. CPCB convened

Page 15 of 52
meetings of distilleries on 11-05-2017 and 24-05-2017 in Lucknow. In these meetings it
was decided that all concerned units will submit Effluent Treatment Plant (ETP) adequacy
reports and upgradation plan duly validated by reputed institutions like IITs or Vasantdada
Sugar Institute (VSI) or National Sugar Institute (NSI). Subsequently, CPCB issued
Direction during January to June, 2017 under Section 5 of the Environment (Protection)
Act, 1986, to 40 operating molasses based distillery units
CPCB has also constituted an expert committee to formulate Action Plan/ Charter
for upgradation of manufacturing process technology, effluent treatment system to
ensure adoption of best practices for effective spent wash management by distilleries
identified to be discharging effluent into river Ganga main stem and its tributaries.
The terms of references of this expert committee were as follows,
1) To identify and assess issues related to environmental pollution from Distilleries.
2) To assess availability and efficacy of cleaner/advance technology, state of the art
technology and to formulate an Action Plan/Charter for upgradation of manufacturing
process technology, effluent treatment system and adoption of best practices for
implementation of spent wash management by distilleries identified as discharging
effluent into river Ganga main stem and its tributaries and to prepare a time bound
road map for it.
3) To assess and validate reports related to manufacturing process technology, effluent
treatment system adequacy, augmentation/upgradation action plan, water audit
&mass balance, assessment of spent wash and other effluent generation and
action plans for implementation of the spent wash management, prepared by
individual distilleries identified to be discharging effluent into river Ganga main stem
and its tributaries.
The Expert Committee consisted of representatives from IIT, VSI, NSI, All India Distillers’
Association (AIDA), Indian Sugar Mills Association and industry representatives. The
Charter has been developed based on the deliberations that took place during the several
meetings of the Expert Committee.

The main objective of formulating the Charter is to encourage the distilleries operating in
the Ganga basin to comply with the prescribed environmental norms, accomplish desired
level of environmental protection and achieve the objectives of the National Mission for
Clean Ganga. The objectives can be achieved through upgradation of process and
downstream effluent treatment technologies, along with upgradation of practices and
environmental performance, besides substantial reduction of freshwater consumption as
well as wastewater generation.
The Charter takes a holistic approach for pollution prevention, adoption of best
practices, improvement/upgradation options in process and effluent treatment
technologies including reduction of freshwater requirement through water recycling and

Page 16 of 52
implementation of on-line monitoring system. However, it is mandatory for the distillery
industries to comply with the prescribed norms. The Charter will facilitate distilleries to
achieve prescribed norms as well as initiate sustainable pollution control measures.

8.0 Proposed Strategy with holistic approach

Distillery sector poses two main problems - one, it has extremely high pollution potential
and two, it is extremely water intensive.
- Pollution caused by distillery spent wash is one of the most critical environmental
problem. Therefore, strict effluent discharge standards were notified by Ministry of
Environment and Forest (MoEF), Government of India vide GSR 176(E), April 2,
1996, the effluent from distillery industry should have pH between 5.5-9.0,
suspended solids 100 mg/l, and maximum BOD level of 30 mg/l for disposal into
surface water and 100 mg/l for disposal on land. It also suggested that all efforts
must be done to remove colour and unpleasant odour, as far as possible. The
discharge standards for fermentation industries as per amendment are presented
in Table 5. Despite standards imposed on effluent quality, untreated or partially
treated effluent very often finds access to watercourses. Therefore, distillery waste
management through exploitation of its nutritive potential for production of various
high value compounds is a sustainable holistic waste management approach.

Table 5: Standards notified by MoEF vide GSR 176(E), April 02, 1996 for
fermentation industry
Industry Parameters Standard
Fermentation Concentration in the effluent
industry (Distilleries, not to exceed mg/l (except
Maltries & Breweries) for pH and colour & odour)
pH 5.5-9.0
Colour & Odour All efforts should be made to
remove colour & unpleasant
odour as far as practicable
Suspended solids
100 100 mg/l
BOD (3 days at 30 mg/l for disposal into inland
27°C) surface water/river/stream

100 mg/l for disposal on land or

for irrigation
1

- Management of water in the distilleries needs a two pronged action plan. First is to
reduce water consumption through process improvements along with reduction in
fresh water consumption through recycle and reuse of water. Several technological
and process improvement options are available to reduce net freshwater
consumption, thereby reducing the amount of effluent generated. Second is to

Page 17 of 52
 have quantum improvement in the individual Effluent Treatment Plants (ETPs) by
adding effective and additional treatment units. This would result in achieving
necessary material balance as well as producing industry grade water reusable for
molasses dilution or as make-up water in cooling towers.
The Charter is aimed at facilitating distilleries to shift from an end-of-pipe treatment
approach to an integrated water and waste management system based on green chemistry
concept.

Other suggested strategies include:

a. A strict metering of the water used and spent wash generated is recommended.
b. Extensive and regular monitoring protocol is to be followed by regulatory
authorities for improved environmental performance of the distilleries.
c. Third party involvement is recommended for planning, assessment, design and
monitoring of implementation measures as prescribed in the Charter. In this
regard, IITs, VSI and NSI as well as Distillers’ Associations can play a pivotal role
in facilitating the individual distilleries, concerned SPCBs as well as CPCB in
implementing the Charter in a time bound and efficient manner.

Various important factors viz. present capacity of each distillery in Ganga River Basin, raw
material being used (whether sugarcane juice, BH molasses or C heavy molasses), quality
of molasses available (in case if molasses is used), fermentation & distillation technologies
adopted, number of working days, generation of spent wash per liter of alcohol production,
present treatment scheme adopted for treatment and disposal of distillery effluent,
availability of filler material/press mud for scientific un-leachable bio-composting and
availability of utilities such as steam, power, water etc. for proposed spent wash
management scheme can be taken into consideration while preparing the action plan for
each distillery.

9.0 Benchmarking of process technology vis-a-vis spent wash

generation norms

The manufacture of ethanol involves two main processes-fermentation and

distillation.

a. Fermentation: Alcoholic fermentation is the process in which sucrose and reducing

sugars (i.e. glucose and fructose) present in molasses are converted into ethyl
alcohol and carbon dioxide by the action of several enzymes present in yeast.
However, all the sugars cannot be converted into alcohol. Some sugars get
converted to products other than ethyl alcohol such as yeast cell biomass, glycerol,
succinic acid and other minor by-products leading to decrease in ethanol yield.
Typically, based on the quality of molasses available in UP and neighbouring states,

Page 18 of 52
 1 MT of C heavy molasses containing 38-40 % Fermentable Sugars (FS) (sucrose
+ glucose + fructose) can yield about 225 to 235 liters of Rectified Spirit (RS). As
mentioned earlier, the fermentable sugar content of the molasses plays an
important role in alcohol yield. The spent wash generation in distillery also depends
on fermentation process technology and alcohol concentration achieved in
fermented wash (Table 6). There are three major types of fermentation process
technology, namely, batch fermentation, fed batch fermentation and continuous
fermentation which are elaborated in Section 12.0. The higher the alcohol
concentration achieved in fermentation, lower will be (i) fresh water requirements
for molasses dilution, (ii) spent wash generation, and (iii) steam requirement for
distillation.
Table 6: Comparison of different fermentation systems using C heavy molasses
Sr Parameters Batch Fed-batch Cascade Biostil
No Fermentation fermentation continuous Continuous
Fermentation fermentation
1 Fermentation 87-88 88-90 89-91 90-91
efficiency
2 Alcohol % in 8.0-8.5 9.0-10.0 8.5-9.5 8.0-8.5
wash (v/v)
3 Molasses quality Can work with Can work with Requires good Requires good
poor quality of poor quality of quality quality
molasses molasses molasses molasses
4 Retention time, 28-30 28-30 22-24 8-9
hr
5 Spent wash 14-15 8-9 9-10 6-7
generation, L/L (with weak
of alcohol beer recycle)
6 Susceptibility to Not highly Not highly Highly Not
contamination susceptible susceptible susceptible susceptible

b. Distillation: It is a purification step wherein the fermentation wash generated in

the fermentation section, is subjected to heat in the analyser column to separate
alcohol from the wash on the basis of difference in boiling points. The alcohol is
further subjected to purification in the pre rectifier and rectifier columns to obtain
rectified spirit (95% v/v). Distillation is the most energy consuming process and
hence is provided with utmost automation and is designed for maximum energy
conservation. There are two types of distillation: conventional atmospheric
distillation and multipressure distillation systems. Multipressure distillation systems
offer several advantages such as reduced steam consumption, improved alcohol
quality because of improved separation of impurities, reduced scale formation,
reduced spent wash generation, PLC based automatic operations, reduced
formation of impure alcohol etc.

Page 19 of 52
 The comparison between atmospheric and MPR distillation systems is given in the
following Table 7.

Table 7: Comparison between atmospheric and MPR distillation systems

S. Particulars Atmospheric Multi Pressure
No. Distillation Distillation
1 Distillation Efficiency 97-98% 98.50%

2 Steam Consumption 3.5 Kg/Lit. of R.S. 2.2 Kg/Lit. of R.S.

production production
3 Impure spirit production 10-15% 5-6%

4 Down Time Very frequent due to Rare shutdown are

scaling problems in required for very short
wash boiling column duration
5 Plant operation Manual PLC/SCADA based
control
6 Spent wash generation 12-15 Lit/Lit of 9-10 Lit/Lit of alcohol
alcohol production production
7 Reuse of steam Nil 80 % condensate can be
condensate used as boiler feed
water
8 Finished products Configured to Two products can be
produce one at a produced depending on
time requirement
9 Quality of As per I.S. Better resolution of
R.S./ENA specifications impurities. Matches with
international
specifications
10 Selling price Lower than same Higher than same
alcohol produced in alcohol produced in
MPR distillation atmospheric distillation
plants plants

It is difficult to benchmark the process technology with spent wash generation as the spent
wash generation largely depends on the alcohol concentration achieved in fermentation
which in turn depends on the quality of raw material/molasses available, strain of yeast
used and other parameters maintained during the fermentation.
Depending upon the technologies used for fermentation, distillation and downstream
effluent treatment as well quality of molasses used, the spent wash generation can vary
from 1.5 to 15.0 liters per liter of alcohol produced in case of C heavy molasses.

As mentioned previously, GOI has allowed use of BH molasses or sugarcane juice/ syrup
from the sugar season 2019-20 for production of ethanol. With these type of cleaner
substrates, the quantity of spent wash generation is reduced and at the same time the
characteristics in terms of COD and BOD are also reduced ultimately resulting in reduced
pollution load on downstream effluent treatment system as well as reduction in fresh water
consumption in distilleries.

Page 20 of 52
In addition, it may be noted that distilleries are now achieving 12-13 % alcohol in wash
with BH molasses and 12-14 % with Syrup and therefore the volume of SW generation is
reduced with consequent decrease in fresh water consumption. Fermentation efficiencies
has also increased by at least 1 to 2 units with use of such cleaner substrates.

10.0 Water Consumption in Molasses based Distilleries

Distillery is a water intensive sector. Water is required for dilution of molasses during
fermentation, dilution of spirit during distillation (extractive distillation), for generation of
steam, as make-up water in cooling towers as well as for non-process application such as
for pump gland cooling, vacuum pump, floor and fermenter washing etc. Due to variations
in the process as well as quality of raw material (molasses), the total fresh water
consumption range from 10 to 20 liters per liter of alcohol production. As per the norms,
total fresh water consumption allowed in molasses based distilleries is 15.0 liters for every
liter of alcohol production. Higher the water consumption, higher is the volume of spent
wash generation having high pollution load. However, advancements in process
technologies has lowered fresh water consumption. Table 8 shows the specific fresh water
consumption corresponding to different process technologies in case of C heavy molasses.

Table 8: Process technology and corresponding specific fresh water

consumption and specific spent wash generation
Sr. No. Process technology Fresh water Spent wash
consumption generation
(KL/KL)
1. Typical batch fermentation+ 20 15
atmospheric distillation
2. Cascade continuous 18 12
fermentation+ atmospheric
distillation
3. Biostill continuous 14.5 9
fermentation+ atmospheric
distillation
4. Biostill continuous 12 8.0
fermentation+ MPR distillation
5. Fed batch fermentation+ MPR 12 8.5
distillation

Page 21 of 52
11.0 Guidelines for Molasses based Distilleries

1. Molasses based distilleries in India are now classified under the “Red Category”.
2. Ministry of Environment and Forest (MoEF), Government of India vide GSR 176(E),
April 2, 1996, notified the discharge standards for fermentation industries including
molasses based distilleries. As per the standard, the effluent from distillery industry
should have pH between 5.5-9.0; suspended solids 100 mg/l, and maximum BOD
level of 30 mg/l for disposal into surface water and 100 mg/l for disposal on land.
It also suggested that all efforts must be done to remove colour and unpleasant
odour, as far as possible.
3. The traditional aerobic and anaerobic methods were incapable of treating spent
wash to meet the environmental standards. Biomethanation of raw spent wash is
one of the prominent primary treatment methods used in Indian molasses based
distilleries. However, even after bio-methanation, the COD and BOD levels are quite
high and the colour parameter is extremely high thereby indicating that it is not
possible to dispose this primary treated spent wash though drains or through
uncontrolled or indiscriminate land application.
4. In 2003, CPCB issued charter on Corporate Responsibility for Environmental
Protection (CREP) for the existing molasses based distilleries wherein five
technologies, namely ferti-irrigation, one time controlled land application (pre-
sown irrigation application), bio-composting practices, concentration-incineration
system and controlled discharge of pre-treated spent wash into deep sea, were
identified for spent wash management so as to minimize the impacts on recipient
environment and asked distillery units to comply with any one or any combination
of the five technologies within a period of three years.
5. Between 2006-2010, performance assessment of CREP guidelines was carried out
by CPCB officials through surprise inspection of molasses based distilleries. As per
the assessment report, there was more than 60% cases of serious non-
compliances. Thus, it was resolved that all non-complying distilleries shall switch
over to emerging technologies from existing technologies of composting, ferti-
irrigation and one-time land application of spent wash in a time bound manner and
shall achieve zero liquid discharge.
6. In the 147th meeting of the Central Board held on 23 rd May, 2008, the following
decisions were made:
a. Proposals for establishing stand-alone distilleries involving composting, ferti-
irrigation and one-time land application of spent wash may not be considered
by SPCBs/PCC and MoEF.
b. Proposals for establishing distilleries attached with sugar unit may be
considered if they follow any one of the following options:

Page 22 of 52
 - Biomethanation followed by bio-composting; or
- Reboiler/Evaporation/Concentration followed by incineration of
concentrated spent wash in boiler (for power generation).
c. The proposals of existing stand-alone distilleries for increase of
production/expansion based on composting, ferti-irrigation and one-time land
application of spent wash may not be considered henceforth by
SPCBs/PCC/MoEF.
d. The existing distilleries (both stand alone and attached with sugar units) that
are not complying will be required to switch over to emerging technologies
from the existing technologies (composting/ferti-irrigation, one-time land
application) in a time bound manner.
7. In 2015, CPCB issued a direction dated 07.12.2015 under Section 18(1)(b) to all
SPCBs to ensure implementation of zero liquid discharge in all the molasses based
distilleries including yeast manufacturing units by following either of the two routes
as specified below;
a. Installing systems for solid separation for reduction in volume of spent wash
and evaporation – concentration or only evaporation – concentration so as to
reduce the volume to min. 40% with 30% solid conc. and water conservation
by using appropriate technology such as RO & MEE or only MEE followed by bio
composting with press mud from sugar industry.
Installing system for Evaporation – concentration by using appropriate
technology such as M.E.E. and Incineration boiler (Slope fired / mixed with aux.
fuel, etc.), using appropriate technology.
New standalone distilleries/expansion of existing standalone distilleries shall
achieve ZLD by concentration and incineration alone.
b. Installing advance process technologies (continuous fermentation, multi
pressure distillation, integrated evaporation, etc.) for reduction of spent wash
generation to 6-8 KL/KL of alcohol produced followed by evaporation –
concentration and incineration, using appropriate technology such as M.E.E.
and incineration boiler.
In addition, industries opting for bio composting shall be directed to comply with the
following within the given time frame;
a. Obtaining valid registration/certification for the production and quality of bio-
enriched Organic manure (bio compost) as per Gazette Notification S.O. 2776
(E) dated 10.10.2015 under the Fertilizer (Control) Fourth Amendment Order,
2015 issued by Ministry of Agriculture and Farmers Welfare (Dept. of
Agriculture, Cooperation and Farmers Welfare) from the Ministry of Agriculture/
concerned agency – within a time period of four months.

Page 23 of 52
 b. The final storage capacity of concentrated spent wash after R.O. & M.E.E. or
only M.E.E., utilized in bio composting shall be properly lined and made
impermeable and shall be strictly restricted to thirty days equivalent of
concentrated spent wash (40% by volume of spent wash generated) –by
31.03.2016.
c. The finished bio-compost shall be packed in sealed poly bags super scribed
with quality and composition of bio compost along with the name of the
manufacturer industry. Industries shall not be allowed to sale compost in open
tractors/trolleys.
d. The bio composting activity shall only be carried out under covered premises –
by 31.03.2016.
Industries opting for concentration-incineration system shall restrict the
impermeable storage of spent wash at any stage, to 07 days equivalent of production
and excess storage facilities beyond this shall be levelled/dismantled by 31.03.2016
or 30.09.2016 as applicable.

12.0 Available Effluent Treatment routes for achieving ZLD

The adoption of zero liquid discharge by molasses based distilleries led to reduction in
BOD load from 5.41 TPD in 2017 to 0.026 TPD in 2019 while compliance of distilleries
increased from 31% in 2017 to 87% in 2019. In addition, average fresh water consumption
for every litre of alcohol produced by distilleries has been reduced from 15 KL per KL of
alcohol in 2017 to 10.25 KL per KL of alcohol in 2019; while spent wash generated for
every litre of alcohol produced, reduced from 11.1 KL per KL of alcohol production in 2017
to 8 KL per KL of alcohol production in 2019.

The various combinations of effluent treatment technologies which have been adopted by
the distillery sector to achieve ZLD are briefly described below.

CPCB does not prescribe or suggest any specific technology to meet the
prescribed norms as a policy matter. It is the responsibility of the industry to
adopt suitable technologies to achieve ZLD.

Page 24 of 52
1.

concentrate
Bio-methanation MEE Bio-
composting

condensate

Treated water re-

CPU use in plant

In this route raw spent wash is fed to bio-methanation plant after cooling and bio-
methanated spent wash is further concentrated to about 30 % solids through a multiple
effect evaporator. The concentrated spent wash is further bio-composted with filler
material such as press mud cake. The evaporation plant process condensate and other low
strength effluents are then treated in a Condensate polishing Unit (CPU) of suitable
technology and treated water is recycled back for molasses dilution or as make-up water
for cooling towers.
2.

Reject
Bio- concentrate
RO MEE Bio-
methanation composting

condensate
Permeate

Treated water
CPU
re-use in plant

In this route raw spent wash is fed to bio-methanation plant after cooling and bio-
methanated spent wash is first concentrated in a Reverse Osmosis (RO) membrane plant.
The reject from RO plant is further concentrated to about 30 % solids through a multiple
effect evaporator. The concentrated spent wash is further bio-composted with filler
material such as press mud cake. The evaporation plant process condensate, RO permeate
and other low strength effluents are then treated in a Condensate polishing Unit (CPU) of
suitable technology and treated water is recycled back for molasses dilution or as make-
up water for cooling towers.

Page 25 of 52
3.

concentrate
Reject

concentrate
Integrated Bio- RO MEE Bio-
MEE methanation composting

condensate RO Permeate condensate

CPU Treated water

re-use in plant

In this route raw spent wash is first concentrated though integrated multiple effect
evaporator. The MEE concentrated spent wash is then fed to biomethanation plant after
cooling and bio-methanated spent wash is then concentrated in a Reverse Osmosis (RO)
membrane plant. The reject from RO plant is further concentrated into MEE before bio-
composting with filler material such as press mud cake. The evaporation plant process
condensate, RO permeate and other low strength effluents are then treated in Condensate
polishing Unit (CPU) and treated water is recycled back for molasses dilution or as make-
up water for cooling towers.
4.

Supporting fuel
concentrate

Spent MEE Incineration Scientific Ash

wash boiler disposal

condensate

CPU Treated water

re-use in plant

In this route the raw spent wash is first concentrated though a combination of MEE plants
and concentrated spent wash at about 55-60 % solids is fired along with subsidiary fuel
(coal or bagasse or rice husk) in specially designed incineration boiler. The high pressure
steam produced in the incineration boiler after passing through a turbine is used as process
steam in the distillery and MEE plant. The turbine generates electricity necessary for

Page 26 of 52
distillery plant operation. The evaporation plant process condensate and other low strength
effluents are then treated in Condensate polishing Unit (CPU) and treated water is recycled
back for molasses dilution or as make-up water for cooling towers.
5.

concentrate
Bio- MEE Dryer (Spray/Agitated thin film
methanation evaporator)

condensate
Powder

CPU Treated
water re-
use in Sold as low Burnt in the
plant grade potash boiler with
supplementary
fuel

In this route raw spent wash is fed to bio-methanation plant after cooling and bio-
methanated spent wash is further concentrated to about 40-45 % solids through a multiple
effect evaporator. The concentrated spent wash is further dried to powder form through a
specially designed dryer system (spray or twin flash or Agitated Thin Film Evaporator
(ATFE)). The spent wash powder produced can be sold as low grade potash or can be burnt
along with some subsidiary fuel in a boiler. The evaporation plant process condensate and
other low strength effluents are then treated in Condensate polishing Unit (CPU) and
treated water is recycled back for molasses dilution or as make-up water for cooling
towers.

6. A new ZLD route for recovery of FCO grade Potash Fertilizer and potash free
organics/de-potash vinasse (DPV) from spent wash.

In this patented technology raw spent wash is concentrated to about 25% solids through
a multiple effect evaporator (MEE). The concentrated spent wash is then subjected to pre-
treatment steps, involving coagulation & clarification / filtration operations, to remove
suspended & colloidal particulates and undesired inorganic contaminants.

Page 27 of 52
 concentrate
Spent MEE Reactor-1,2,3,4 MEE De-potash
wash Vinasse

condensate condensate

CPU

FCO Grade Potash

Treated water Fertilisers
re-use in plant

Subsequently the treated & concentrated spent wash is reacted & filtered for recovery of
insoluble potassium salt (as residue) & lean spent wash (as filtrate). The potassium salt is
further processed for production of FCO grade potash fertilizer (KCl / K2SO4 / KNO3 /
KH2PO4 etc.) through reaction, filtration, evaporation & drying steps. Lean spent wash is
further treated & concentrated to produce De-potash Vinasse (DPV) [TS: 50-60%].
Condensate streams from evaporation operations (MEE) are treated in Condensate
polishing Unit (CPU) and treated water is recycled back for molasses dilution or as make-
up water for cooling towers. The process works in similar fashion with bio-methanated
spent wash also.

CPCB is open to other advanced technologies which have been evaluated for their
techno-economic viability and operational performance through reputed
institutions and which can lead to prevention, control and abatement of pollution
in distilleries.

Page 28 of 52
13.0 Best Available Technologies

13.1 Yeast Propagation

Most of the distilleries have yeast propagation system where pure yeast culture is
developed from laboratory shake flask level to the pre-fermenter scale. High alcohol
tolerant and fast fermenting yeast is required for achieving high fermentation efficiency
(FE) and high alcohol concentration in fermentation. Propagation of yeast in pure form is
the central and most critical aspect in molasses based distilleries. Propagation has to be
carried out under totally aerobic conditions with least alcohol generation and at the same
time, keeping contaminants at the lowest level. Molasses sterilization/pasteurization has
to be carried-out properly during the different stages of yeast propagation. Proper
precautions have to be taken to avoid contamination at all stages and for maximizing the
yeast count.

New readymade yeast cultures with high alcohol tolerance and high FE in the form
of active dry yeast will be available in the future which will be more expensive but will
reduce the efforts required and cost of propagation.

13.2 Fermentation

In molasses based distilleries fermentation is generally carried out either in batch,

fed-batch or continuous fermentation mode. The scientific information on these modes of
operations with pros and cons of the processes are given below.

It may be noted that batch fermentation has been a traditional method of

fermentation that ends up with lowest fermentation efficiency (FE) and has been replaced
either by continuous fermentation or fed-batch fermentation systems.

Continuous fermentation systems provide steady state conditions with respect to

time, results in maximum FE and easy to operate. However, continuous fermentation is
susceptible to contamination and poor quality of molasses. Cascade continuous
fermentation consisting of four fermenters has been most successful under Indian
condition.

Cascade continuous fermentation with cell recycle has also been tested in India but
suffered with severe contamination problems and thus was not very successful because of
inferior quality of C heavy molasses produced by Indian sugar mills.

Biostill continuous fermentation with cell and weak beer recycle has been used by
many distilleries and theoretically can result in maximum FE, lowest molasses dilution,
lowest water requirement as well as lower spent wash generation. However, there have

Page 29 of 52
been some issues with fermentation of poor quality molasses and quality of spirit produced
particularly from viewpoint of its potable use. Therefore, most of the Biostill fermentation
plants in UP and neighbouring states have been modified to cascade continuous or fed-
batch fermentation systems.

Fed-batch fermentation has been adopted recently in Indian molasses based

distilleries particularly to cope-up with poor quality of molasses and to achieve higher
concentration of alcohol in fermentation broth. Though the FE achieved is slightly less than
continuous fermentation systems, the advantage is substantial reduction in spent wash
(SW) generation because of higher alcohol concentration achieved in fermentation. Capital
investment for fed-batch fermentation system is also higher than other fermentation
systems. A four fermenter fed-batch system is commonly used in Indian molasses based
distilleries.

From the viewpoint of best available technology (BAT) for upgradation, it can be
said that depending on quality of molasses available, continuous or fed-batch fermentation
system are most suitable for Indian distilleries.

13.3 Fermentation with spent wash recycle

With stringent norms being implemented by pollution control authorities, scarcity

of water and the realization of the waste to wealth concept with regard to effluent
generated, has resulted in distilleries working towards better effluent treatment and
disposal strategies. For example, adoption of continuous fermentation process which
involves recycling of spent wash, has led to reduction in water requirement for molasses
dilution as well as reduction in volume of effluent generation. However, it may be noted
that recycling of spent wash can affect the final product quality, particularly in the case of
potable alcohol. Therefore, manufacturers of potable alcohol will have to show caution
while utilization of fermentation processes involving spent wash recycling.

13.4 Distillation

Traditional method of distillation has been the atmospheric distillation system.

However, it has been replaced by multipressure (MPR) distillation systems in many
distilleries. MPR distillation systems are based on heat integration concept and incorporate
some columns that run under vacuum, some under pressure and some under atmospheric
conditions. Reboilers are also incorporated for most of the columns that avoid direct
sparging of steam in the columns. Though the capital investment in MPR distillation
systems is higher, it offers several advantages such as reduced steam consumption,
improved alcohol quality because of improved separation of impurities, reduced scale

Page 30 of 52
formation, reduced spent wash generation, PLC based automatic operations, reduced
formation of impure alcohol etc. as compared to atmospheric distillation systems.

From the viewpoint of BAT for upgradation, it may be stated that MPR distillation systems
are advantageous with respect to reduction in spent wash quantity. Fed-batch
fermentation coupled to MPR distillation can result in lowest SW generation, depending on
quality of molasses available. It may also be noted that though the volumetric generation
of SW will be reduced, the total BOD/COD load (MT/day) will remain the same.

14.0 Distillery Effluent Treatment Technologies

There are many technologies available to treat the spent wash generated by distilleries.
Various biological treatments (anaerobic and aerobic), controlled land application,
physicochemical and thermal treatments have been used in the past. Often the capital
cost involved in the treatment of this huge quantity of distillery spent wash to the
stipulated standards is equal to or higher than the cost of distillery plant itself. Hence,
there has been a shift from end of pipe treatment to an integrated waste management
comprising of plant control, solid waste management and recovery from waste for
achieving Zero Liquid Discharge.
For treatment of spent wash, various technologies are now available such as
reboilers, integrated evaporation systems, bio-methanation, multiple effect evaporation
(of raw or bio-methanated spent wash), reverse osmosis (of bio-methanated spent wash),
bio-composting, incineration of concentrated spent wash, spent wash drying. Each of these
methods have certain advantages and limitations which are briefly described below.

14.1 Bio-methanation

Biomethanation of distillery spent is now a well-established effluent treatment system in

Indian distilleries with attractive returns in terms of generation of biogas as an energy
source (Biogas: 4500–5000 Kcal/m3) with substantial reduction in pollution load. It is also
characterized with low production of waste biological solids, low process energy
requirement, low nutrient requirement and improving the pH of acidic spent wash. High
loading rates can be achieved and active-anaerobic sludge can be preserved for many
months. Ideally, distilleries with bio-methanation should run throughout the year.
Therefore, bio-methanation is not suitable for seasonal distilleries. CSTR, UASB and
thermophilic type digesters are more suitable for molasses based distilleries. Biogas based
power generation or CNG (CBG) production can offer higher returns.

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14.2 Reverse osmosis (RO)

Reverse osmosis is a membrane based separation technique. The feed stream is physically
split into permeate and reject. The majority of the dissolved salts, low molecular weight
organic materials, heavy metals, bacteria, viruses and suspended solids etc. are retained
by the membrane and are discharged from the system with the brine. An RO membrane
typically rejects 99 % of most ions and most organics over 150 MWCO (molecular weight
cut off). About 100 RO plants have been installed in distillery industry in the country. Disc
and tube configuration is well established with average 50 % recovery of permeate from
BMSW. In operation of RO plants, suspended solids is the most critical factor and needs
to be maintained below 2000-3000 ppm. Frequent choking of RO membrane is a common
problem faced by distilleries. Permeate can be recycled after proper treatment as make-
up water in cooling towers or for molasses dilution. Operational cost is slightly less than
MEE plants.

14.3 Multiple Effects Evaporators (MEE)

Falling film or forced circulation or fluidized bed evaporators or combination of these are
now being used to concentrate raw or bio-methanated spent wash in distilleries. MEEs are
highly responsive to alterations of parameters such as energy supply, vacuum, feed rate,
concentrations, etc. When equipped with a well-designed automatic control system, they
can produce very consistent concentrated product. The fact that falling film evaporators
can be operated with small temperature differences makes it possible to use them for
concentration up to 30 % solids with low power consumption and short retention time.
MEE plants can be operated at much lower ΔT (difference between jacket and liquid boiling
temperature) that is favorable to vapour recompression and consequently, the energy
consumption can be reduced.
More than 200 MEE plants have been installed so far in the distillery sector of the
country. Scaling can be a severe problem when product concentration above 40 % solids
is attempted to be concentrated and it is difficult to remove the scaling. Process
condensate requires polishing treatment before reuse in process and non-process
applications. Therefore, additional treatment cost is involved. However, integrated raw
spent wash evaporation can result in reduction of final SW volume to 3.5 to 6.5 lit/lit
without additional steam requirement depending on fermentation technology employed.
It may be noted that evaporation of bio-methanated spent wash through MEE
system is not an easy task. The pH and dissolved gases in bio-methanated spent wash
can affect the performance of such type of evaporators.

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14.4 Bio-composting

Bio-composting of distillery spent wash (concentrated 40% by volume of spent wash

generated and 30% solid concentration) with filler material such as press mud cake is a
well-established solid phase fermentation technology that can result in ZLD with negligible
power requirement. This technology is suitable to the distilleries attached with sugar mills.
Bio-compost produced is rich in organic and inorganic micronutrients, which can be sold
to farmers and substantial amount of income can be generated. Availability of sufficient
quantity of filler material and operation during rainy season are the bottle-necks in
operation of bio-composting system.

14.5 Incineration of distillery spent wash

Concentrated spent wash can be combusted along with supplementary fuel and entire
effluent can be converted into potash rich ash. The thermal energy generated during
incineration can be converted in to steam and power and the unit can become self-
sufficient in captive consumption of steam and power. There are about 40 spent wash
incineration units established in Indian distilleries. Early units have faced serious problems
of scaling in evaporators and inherent challenges of ash deposits and clogging in the heat
transfer areas of the incinerator. Boiler cleaning frequency is ranging between 15 to 45
days. Due to frequent stoppages and the cleaning process, the incinerator undergoes a
cyclic thermal shock resulting in reduced life of the equipment. Desired emissions norms
can be achieved by installing multi-cyclone separators or bag filters or electrostatic
precipitator. Process Condensate streams can be treated and recycled back for process
and non-process applications leading to Zero Liquid Discharge.

14.6 Drying of Spent wash

In effluent treatment system, drying is usually the last stage of the system and involves
final removal of effluent from the material to convert it in a solid material. Drying is defined
as removal of small amount of water from a material by application of heat. Drying
commonly involves removal of all or most of the liquid by supplying latent heat to cause
thermal vaporization.
Drying makes material (or effluent) more convenient in storage, packaging,
transportation, preserving and at the same time improves the quality of final product.
Different types of dryers have been used for spent wash drying such as spray dryer,
double drum dryer, spin flash dryer, agitated thin film dryer/evaporator etc.
Other technologies such as aerobic treatment, one time controlled land application
of bio-methanated spent wash, ferti-irrigation, mist evaporation etc have been used in
past but are now not allowed/encouraged.

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14.7 Condensate Polishing Unit (CPU) Technologies

In molasses based distilleries there are two types of effluent, one is high strength effluent
i.e. spent wash and the second is usually a mixture of low strength effluents i.e. process
condensate (from evaporation of BMSW as well as from evaporation of RSW), reverse
osmosis (RO) permeate, spent lees, cooling tower blow down, floor washing, laboratory
water etc. The low strength effluents in distillery can be recycled back for process and
non-process applications after proper treatment. The technology which is used for
treatment of low strength effluents is generally called as Condensate Polishing Units (CPU).
By using CPU, the low strength effluent quality can be transformed into suitable water
quality for process and non-process applications.
Treatment of MEE condensate and RO permeate is necessary before utilization in
process activities such as dilution water in fermentation process and as cooling tower make
up because MEE condensate and RO permeate contain high COD and volatile fatty acids
which contribute to low pH and chemical impurity. Condensate with low pH can lead to
retardation of yeast activities and subsequent yield reduction if it is utilized for fermenter
dilution. Also, utilization of condensate with low pH as cooling tower makeup water can
lead to corrosive damage to the pipelines. Therefore, utilization/recycling of MEE
condensate and RO permeate along with other low strength effluents is not feasible unless
it is treated in Condensate Polishing Unit to alkalize the treated condensate to a desirable
range of pH (6 - 6.5).
A CPU enables the treatment of all low strength effluents generated during
treatment of spent wash. This CPU treated water can be recycled back in process/ non-
process activities within the distillery premise and hence no liquid will have to be
discharged outside by the distillery. Therefore, the role of CPU has become very important
in achieving ZLD.
There are several CPU technologies introduced during last 5 years in the distilleries.
The following CPU technologies are generally used in distillery industry:
1. Conventional (anaerobic followed by aerobic followed clarification followed by
polishing) technology with or without ozonation.
2. Aerobic treatment (such as diffused aeration) followed by clarification system
followed by Ultra Filtration (UF) or Reverse Osmosis (RO)
3. Membrane (RO) Technology-Pretreatment followed by RO technology
4. CPU Technology based on Stripping with steam, followed by Ozonation followed by
RO
There are different merits and demerits of these technologies and properly selected
technology has to be adopted depending on fresh water requirements in the distillery.
Conventional technology seems to be well established providing desired results in terms
of treated water quality and percentage recovery. However, other cost-effective

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technologies are also being developed and will be used by distilleries in future. There is a
need to evaluate such technologies and therefore, sufficient time should be given to
molasses based distilleries to implement them. Distilleries that are proposing to any other
advanced technology than what is mentioned above shall follow a defined procedure for
verification and ratification of the process which should ultimately ensure that the low
strength effluents are treated as per the prescribed standards and recycled back for
process and non-process applications to achieve Zero Liquid Discharge (ZLD).
Distilleries consume significant quantities of fresh water and it would be appropriate
if distilleries voluntarily to take measures of fresh water conservation.

15.0 Performance Norms and Output Conditions for Effluent

Treatment Technologies

15.1 Biomethanation

About 70 to 80 % distilleries in the country have adopted bio-methanation of distillery

spent wash as the primary treatment method. It is one of the well-established technologies
for distillery effluent treatment with excellent returns in terms of valuable biogas
generation.
Table 9: Biomethanation performance efficiencies
Parameters Values
pH Slightly alkaline
BOD removal efficiency 85-90%
COD removal efficiency 60-65%
Specific biogas generation (NM3/kg of COD destroyed) 0.45 – 0.55
% of Methane in biogas 55-65 %
Output Conditions:
1. Characteristics depends on above mentioned performance efficiencies.
2. Temperature- 36-380C for mesophilic reactors.
3. Volume remains the same.

15.2 Reverse osmosis

Reverse osmosis is a membrane based separation technique. A membrane is a selective

barrier that permits the separation of certain species in a fluid by a combination of sieving
& sorption mechanisms. The feed stream is physically split into permeate (or filtrate)
comprising molecules that pass through the membrane and reject (or retentate or
concentrate) that is composed of the molecules retained by the membrane.

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Table 10: Reverse Osmosis Performance Parameters
Sr. Particulars Type of spent wash used
No. (Permeate From Raw spent From Bio-methanated
characteristics) wash spent wash
1. Permeate recovery, 35-40 45-50
%
2. pH 2.9-3.5 6.8 - 7.2
3. COD, mg/l. 620.0 119.5- 235.0
4. TDS, mg/l. 400.0 200.0-350.0
5. TSS, mg/l. 220.0 NIL
Output Conditions:
1. Characteristic of treated effluent (reject) will depend on the input characteristic of
feed spent wash.
2. General characteristic of permeate will typically be as given in above table and can
vary depending on the input characteristic of feed spent wash. Permeate should be
treated in CPU and recycled back for process and/or non -process applications.
3. Treated effluent volume will depend on percentage recovery of permeate.

15.3 Multiple-effect evaporation (MEE) of distillery spent wash

The function of a MEE is to concentrate a non-volatile solute from a solvent, usually water.
Depending on the number of effects used in an evaporator the quantity of water
evaporated per kilogram of steam increases.
Performance Measures
Main measures of evaporator performance:
1. Capacity (kg vaporized/time)
2. Economy (kg vaporized/kg steam input)
3. Steam Consumption (kg/hr)
4. Characteristics of process condensate (COD, BOD, TDS, pH etc.)
5. Characteristics of concentrate (COD, BOD, TDS, pH etc.)
6. Cleaning frequency and cleaning duration.

Output Conditions:
1. Characteristic of concentrate will depend on the input characteristic of feed spent
wash.
2. General characteristic of process condensate can vary depending on the input
characteristic of feed spent wash. Condensate should be treated in CPU and recycled
back for process and/or non -process applications.
3. Concentrate volume will depend on evaporation duty of the MEE plant.

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15.4 Bio-composting

Composting has come to be accepted as one of the good solution to the problem of
distillery effluent treatment. Properly operated bio-composting can result in to zero
effluent discharge. It can be used either as a secondary treatment after anaerobic
digestion or as a tertiary treatment after concentration of spent wash.
Performance norms:
1. It should result in Zero Discharge.
2. There should be no odour or fly nuisance.
3. The finished product should be free from any repulsive odour.
4. The finished product should be baggable product, easy to handle and transport.
5. Bio-compost characteristic should be as per FCO.
6. Bio-compost yard should be made impervious.
7. The spent wash (concentrated) should be stored in impervious tank
8. For 5 to 12 % solids containing spent wash, the filler material (PMC) to spent wash
ratio prescribed is 1: 2.5 for 45 days cycle and 1:3.5 for 60 days cycle.
9. For concentrated spent wash (25 to 30 % solids), the filler material (PMC) to spent
wash ratio prescribed is 1: 1.6 for 60 days cycle.
10. Impervious compost yard area based on material balance (plus ready compost
storage area) should be made available.
11. During rainy season, bio-composting process has to be stopped.
12. However, bio-composting can continue provided covered compost yard of required
area is available.
13. Record of filler material used (PMC) and bio-compost produced/sold should be
maintained.
14. The quality of bio-compost produced should be certified by Ministry of Agriculture

Output conditions:
1. Bio-composting process should result in Zero discharge.
2. The resultant bio-compost of above mentioned quality should be stored on
impervious yard.
3. The bio-compost produced should be should be stored on impervious compost yard.
(Note: Please refer to Annexure-I for Standard Operating Procedure (SOP) for
Bio-composting operations for molasses based distilleries.)

15.5 Incineration of spent wash

Incineration of concentrated spent wash along with some subsidiary fuel in a

specially designed boiler is one of the potential technologies for achieving Zero Discharge.
Concentrated spent wash at about 60 % solids is fired in boiler along with subsidiary fuel

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such as coal or bagasse or other biomass. Either fluidized bed or travelling grate type of
incineration boilers are in use. They can run for 300 or more days in a year.
Performance norms:
1. It should result in Zero Discharge.
2. The boiler should run at the rated capacity and at rated ratio of concentrated spent
wash to subsidiary fuel.
3. The incineration boiler should have installed necessary emission control system such
as ESP or bag filters and should achieve the prevailing norms of boiler emissions.
4. The boiler should have installed on-line stack monitoring system.
5. The boiler cleaning frequency and cleaning duration should be minimum.
Output conditions:
1. Steam should be generated at rated capacity and pressure consistently.
2. The ratio of concentrated spent wash to subsidiary fuel should remain constant.
However, it may be noted that the ratio will change with change in raw material i.e.
in case of B heavy molasses or sugarcane juice or syrup.
3. The ash generated should be disposed of properly.

15.6 Dryers for spent wash drying

Different types of dryers have been used for spent wash drying such as spray dryer, double
drum dryer, spin flash dryer, agitated thin film dryer/evaporator etc.
Performance norms:
1. It should result in Zero Discharge.
2. The dryer should run at the rated capacity producing dry powder without
caramelization and with specified moisture content.
3. The vapour coming out of the dryer should be condensed and the uncondensed
gases/fraction should be properly scrubbed before letting out them to the
atmosphere.
4. The dryer cleaning frequency and cleaning duration should be minimum.
Output conditions:
1. It should produce dry bagable product.
2. Dried product should be stable and not hygroscopic.
3. Condensate collected should be treated in CPU and recycled back for process or
non-process applications.

15.7 Technology for Recovery of FCO grade Potash Fertilizer and potash
free organics/de-potash vinasse (DPV) from Molasses-based
Distillery Spent Wash

In this process, potassium is selectively precipitated as insoluble salt from pre-treated &
clarified spent wash. Subsequently, the potassium salt is converted to FCO grade potash

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fertilizer & lean spent wash is further processed & concentrated to produce De-potash
Vinasse. Water recovered from MEE is processed through CPU for reuse in distillery
operations. This process involves general unit operations practiced in the Industry & can
operate round the year (nominally 330 days). The process works in similar fashion with
bio-methanated spent wash also.
Performance norms:
1. The process would comply with Zero Discharge / Waste concept.
2. Potash recovery efficiency (as K+) would be more than 80%
3. Equipment cleaning & maintenance to be schedule driven (preventive) to eliminate
downtime
4. Plant to be operational round the year (nominally 330 days)
Output conditions:
1. Potassic salts produced should comply with FCO specifications.
2. DPV produced should comply with requirements of cattle feed industries
3. Condensate collected should be treated in CPU and reused in distillery operations.

15.8 Condensate polishing unit

Of the various available technologies available, the conventional technology (anaerobic

followed by aerobic followed by polishing) is well established with desired results. The
typical characteristics of input feed and treated water generated in a conventional CPU are
given below in Table 11.
Table 11: Combined raw spent wash process condensate plus spent lees and
treated water characteristics
Parameters Test values
Feed Outlet of Outlet of UF Outlet of RO
sand filter
pH 3-4 6.5-7.5 6.5-7.5 6.5-7.5
COD, mg/l 6000 100 ˂ 60 ˂ 10
BOD, mg/l 3000 30 ˂ 20 ˂5
TDS, mg/l ˂ 1000 ˂ 1000 ˂ 1000 ˂ 100
Temperature, °C 34-35 --- --- ---

Output conditions:
1. It should produce treated water quality with TDS of less than 2100 ppm
2. Treated water should be suitable for recycle for process (including fermentation) and
non-process applications with pH 6.5-7.5, COD< 100 mg/l, BOD <30 mg/l.
3. Losses should be minimum with yield of treated water in the range 80-98 %.
4. The reject of CPU system (from UF or RO) if any, should be recycled back to effluent
treatment system.
It may please be noted that apart from the conventional technology for treatment of
low strength effluents there are other potential technologies also available as

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 mentioned previously. Irrespective of CPU technology adopted, the charter
prescribes that distilleries should treat the low strength effluents and recycle them
for process and non-process applications.

16.0 Prescribed Standards to be adopted by Molasses based

Distilleries

CPCB does not prescribe or suggest any specific technology to meet the prescribed
norms as a policy matter. It is the responsibility of the industry to adopt suitable
technologies to achieve ZLD as well as to comply with the following:

1. Distilleries shall ensure reduction of spent wash generation to 6-8 liters for every
liter of alcohol produced.
2. Distilleries shall minimize fresh water consumption to 8-10 liters for every liter of
alcohol produced.
3. Distillery sector is a water intensive sector. Therefore, distilleries shall maximize
water conservation and water recycling thereby ensuring ~80% water recovery.
4. Industries opting for bio composting shall ensure the following:
a. For concentrated bio-methanated spent wash (30 % solids), the filler material
(PMC) to spent wash ratio prescribed is 1: 1.6 for 60 days’ cycle.
b. Strict compliance to ‘Standard operating procedure (SOP) for Bio-composting
operation for Molasses based distilleries’.
c. The final storage capacity of concentrated spent wash utilized in bio-composting
shall be properly lined and made impermeable and shall strictly be restricted to
thirty days equivalent of 40% by volume of spent wash generated and 30% solid
concentration. Excess storage facilities beyond this shall be levelled and
dismantled.
d. The distilleries shall obtain valid registration/certification for the production and
quality of bio-enriched organic manure (bio compost) as per Gazette Notification
S.O. 2776 (E) dated 10.10.2015 under the Fertilizer (Control) Fourth
Amendment Order, 2015 issued by Ministry of Agriculture and Farmers Welfare
(Dept. of Agriculture, Cooperation and Farmers Welfare) from the Ministry of
Agriculture/ concerned agency – within a time period of four months.
e. Bio-composting yard has to be impervious with leachate/run away collection
sump well. The impervious bio-compost yard and ready bio-compost storage
area has to be prepared as per the CREP norms with HDPE lining.
f. Refer Annexure I (Standard Operating Procedure for bio-composting operation
in molasses based distilleries) for more details.

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5. Industries opting for incineration shall
a. Restrict the impermeable storage of spent wash at any stage to seven days
equivalent of production and excess storage facilities beyond this shall be
levelled and dismantled.
b. Scientific ash handling, disposal and record keeping.
c. Refer Annexure II (Standard Operating Procedure for incineration operation in
molasses based distilleries) for more details.
6. Industries opting for potash recovery shall ensure
a. potash recovery efficiency of ≥80%.
b. potash rich salts produced should comply with FCO / other regulatory
specifications.
c. proper pre-treatment and treatment of mixture of cleaning agents and
contaminants generated following each CIP routine. Recycling of cleaning
agents/solutions used for CIP following proper treatment should be such that
reuse rate of CIP cleaning agent is more than 95%.
7. All non-process effluents/weak strength effluents should be treated through
adequate Condensate Polishing Unit (CPU) and recycled back. Recovery of reusable
water should vary between 80-98%. The reject of CPU, if any, should be recycled
back to effluent treatment system. Treated water from CPU should meet the
following criteria
a. TDS of less than 2100 ppm
b. Water quality suitable for recycle in process (including fermentation) and non-
process activities with pH 6.5-7.5, COD< 100 mg/l, BOD <30 mg/l.
8. Online Continuous Effluent and Emission Monitoring Services (OCEMS) requirement:
a. Stand-alone distilleries or distilleries having independent boiler should
install on-line emission monitoring system (PM or depending on fuel being
used) as per the CPCB guidelines.
b. PTZ Cameras with night vision to be installed.
c. In case of bio-composting, one PTZ camera with night vision to be installed
in bio-composting yard and one at impervious spent wash storage lagoon.
9. It would be necessary for all distilleries to identify recipient drains/ rivulets and their
u/s & d/s locations in consultation with respective SPCBs, for monthly monitoring by
industry to ensure ZLD from distilleries. The distilleries will have to get the samples
collected from upstream and downstream locations, analysed from EPA/NABL
approved laboratories and the essential parameters to be included are DO, Colour,
BOD, COD, pH, and TSS.
10. Distilleries shall submit monthly report on alcohol production, spent wash generation
and stepwise spent wash treatment.

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11. In case of installation of any new spent wash management system or change in route
for adoption of ZLD, the concerned distillery shall submit an adequacy report duly
validated by recognized technical institutions like VSI, NSI or IITs.

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17.0 Annexure-I: Standard Operating Procedure (SOP) for Bio-
composting operation for Molasses based distilleries

Sr. No. Particulars Time Range

1. Distilleries with covered shed bio-composting may be
allowed to operate throughout the year and those without
covered shed shall be operated 270 days (excluding
monsoon season)

2. Press mud may be directly laid in the bio-compost yard or

properly stored for consumption the rest of the year.

3. Feed stock received as combination of press mud, yeast

sludge and boiler ash in press mud yard or plant as per
requirement from sugar industries.

Average Moisture content after testing : 70±5%

4. Areas for Press mud storage, Bio-compost operation,
Finished goods storage must be properly demarcated.

5. Windrows laid shall be as per the machine size and

length as per the Bio- compost yard (Windows size- 3.5
M width X 1.5 M Height). Distance between two windows
1 M min. (for top mounted aerotiller m/c.)
4th – 8th day
6. On completion of laying & dressing of windrows, initial
turning started to reduce moisture content from 70±5 %
to 50±5 %. Time required for achieving desired moisture
level, in summers 3 to 5 days, winters 4 to 7 days.

7. On achieving 50± 5 % moisture , bio culture (as a seed)

in windrows added and turning of windrow started for
proper mixing of culture seed and allow to increase
windrow’s temperature at around 70 Oc.
8th – 10th day
8. Prepared windrows left idle for 2-3 days to proper growth
of microbes.
9. Growth/ development of microbes in windrows is
observed by measuring its temperature. In normal
condition temperature of windrows are between 60- 70°.
This temperature gain is result of microbial activity.

10. When desired temperature achieved (within 2-3 days),

start turning of press mud through aero tiller machines
without any major deviation in shape & size of windrows.

11. Measure temperature manually with the help of

thermometer.
12. Receive concentrated effluent from plant or lagoon at the
bio compost yard through flow meter.
Spray concentrated spent wash not more than 10% of
13.
press mud weight on alternate days using the aero tiller
or on suitable interval based on windrow temperature &

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 moisture content. (The overall consumption of
concentrated spent wash shall be 1.6 m3/MT of Press
Mud).
Alternatively spent wash can be sprayed on the basis of
moisture content i.e. spraying can take place when
moisture content has come down to 45 to 50% so as to
increase moisture content to about 65 to 70%. During
active Bio composting process the moisture will tend to
go down because of heat generation.
14. During turning & spraying of effluent, monitor the
windrow’s temperature on daily basis and note in the log
book. The quantity of sprayed effluent must be noted down
in the log book.
10th-50th day
15. Concentrated spent wash and turning of windrows
continues for 50-60 days or till the windrows temperature
up to 55+ 5°C maintained.
50th-60th day
16. If no temperature rise is observed, then stop the
concentrated spent wash spray on windrows and continue
the turning of bio-compost till moisture content reaches
35±5 %, Heap the bio-compost about 2 M height to have
aerobic condition.
17. Store the prepared bio-compost under covered condition
during rainy season
18. Bio-compost shall be analyzed for parameters as per the
Fertilizer Control order with latest amendments and shall
be packed as per the customer requirement.

19. Personal Protective Equipment (PPE) as per job

requirement shall be used by personnel working in the bio
–compost yard.
20. Check the top level of concentrated spent wash storage
lagoon on daily basis so as to maintain below Red mark.

21. Bio-compost yard should be cleaned before start of every

monsoon season
Once in month
22. Monthly report has to be submitted to respective SPCB and
during distillery
CPCB which includes quantity of raw spent wash produced, operation
Quantity of Concentrated spent wash produced, Quality of
press mud consumed, quantity of other filler material used
in bio-compost if any along with bio-compost analysis
report

23. Green belt should be developed at bio-compost site as per

CREP norms.
NB: Requirement of Press mud depends on the size of aerotilling machines which are
available in different sizes and also with side mounted turner and top mounted turning
equipment. Further, the windrows require dressing with JCB machine after every turning
for which a spacing of about 3.0 meters is required between each windrow.

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17.1 Specification of covered Bio-compost yard for Distillery operating
throughout year

1. Yard Length: depending upon plot size available covered yard shall be made
after leaving proper circulation area for movement of machinery; on an average
15-20% area may be allocated depending on the shape of the yard, e.g., square
or rectangular yard may need the minimum circulation area where as stepped
yard have the different windrow length need more circulation area.
2. Windrow markers indicating windrow number, date of formation, date of
inoculation and date of the last application of spent wash. Marker shall be made
of MS sheet with rod support, grouted in concrete. Marker shall be painted with
white background and letters in black paint. The windrow marker should be
located in front of windrow after leaving the distance of movement of machines.
3. Bays: Approximately 12.0 meter span, having spacing between vertical columns
5-6 meters, rain water gutter height 6.2 meter, gutter slope of minimum 1 in
200. Gutter MOC HDPE / PE/ GI sheet, discharging into RCC / Cement Plastered
Brick masonry channels connected to leachate collection pits. In case of multiple
down-comers slope is not mandatory. Ridge height will vary upon truss design.
Truss design may have provision of ventilation at the top (North light pattern)
or semi elliptical.
4. Down comers for rain water: Compost shed shall be provided with Rain
gutters and the rain gutters shall be connected to the storm water drain using
HDPE/PE pipe of at least 150 mm ID down-comers discharging into channel.
Channel MOC RCC (M20)/brick masonry cement mortar plastered (1:6)
discharging to either rainwater harvesting pit or to natural stream.
5. Protection against cross wind rain: Rain water entry into the shed shall be
prevented by either providing protection along the sides or by providing Louvers.
6. Leachate collection pits: MOC- RCC (M20) / brick work cement mortar
plastered (1:6). Size: not less than 1.5 meter X 1.5 meter having top level / free
board 300 mm above the ground level.
7. Leachate collection drain: MOC- RCC (M20)/brick work cement mortar
plastered (1:6). Size: 0.3 meter (width) X 0.25 (depth). The depth will increase
along the length towards collection pit. Bed slope: 1 in 200 approx. with smooth
finishing to prevent sludge (press mud) deposition on the base.

8. Truss members: Members size (Diameter, wall thickness) depending on the

safe structural design capable to with stand against design wind load and
rainfall. Material of construction shall be preferably GI pipes/ Galvanized angles
/channel sections / RCC columns. Pre-engineered profiles may also be used.

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 The GI pipes/ channels should be grouted in concrete in the bio compost yard
floor and should be protected by providing concrete cover of at least 150 mm
all-round, at least 300 mm height to prevent corrosion due to direct contact on
the base.
9. Roofing: Poly film minimum 200 micron film with qualities of UV stability, anti-
drip, anti-dust, Light Diffusion minimum 50% film fixing only on roof and gables
and up to hockey purlin/GI sheet/Precoated laminated sheet
10. Floor lining: The floor lining shall be impervious, strong enough to prevent
settlements due to machine load. Minimum thickness 100 mm. The underlining
sheet shall be minimum 150 micron HDPE film below the floor. Clay layer cushion
of 300 mm below the liner and 50 mm above the liner should be provided. In
case of RCC flooring, the construction joint should be sealed using the water
bar/hot bitumen.
11. Ground water monitoring facilities.

a. Location of piezometer wells: Minimum at 4 places along the periphery

of the bio-compost yard such that one is in the upstream of the Ground water
flow direction and one in the downstream direction. For Bio-compost yard of
more than 5 acres area, one additional Piezowells shall be constructed for
every 5 acres and shall be in the downstream direction placed sufficient away
from each other to assess any seepage /ground water contamination tested
quarterly. (Example: for 20 acre Bio-compost yard the total number of
Piezowells shall be 4+3 =7nos. One upstream and 6 down steam uniformly
distributed). Piezo-wells shall be constructed as per the standard procedure
and specifications.
b. Hand pump: at least 30 meters depth, located within 500 meters to 1 Km
from yards. Water quality of hand pump should be tested quarterly.
12. Data recording: Log book at yard should be maintained mentioning the date
of formation of windrow, quantity of press mud, feed stock, date of last aero-
trilling, date of last spent wash spray, quantity of spent wash spray, temperature
date-wise, date of maturity, moisture content etc. Data should also be entered
into the computer for record and computation. The press mud and ready
compost must be weighed and records of the same shall be maintained.
13. Approach Road to bio-compost yard: The entrance of the Bio-compost yard
should be paved all- weather road for approach of vehicles.
14. Storage facilities for ready compost: Covered shed having platform.
15. Camera as per OCEMS guidelines shall be installed in the bio-compost yard to
monitor the bio- compost operations inside the shed.

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17.2 Specification of Bio-compost yard for Distillery operating 270 days
(excluding rainy season)

1. Yard Length: depending upon plot size available yard shall be made after
leaving proper circulation area for movement of machinery; on an average 15-
20% area may be allocated depending on the shape of the yard, e.g., square or
rectangular yard may need the minimum circulation area where as stepped yard
have the different windrow length need more circulation area.
2. Windrow markers indicating windrow number, date of formation, date of
inoculation and date of the last application of spent wash. Marker shall be made
of MS sheet with rod support, grouted in concrete. Marker shall be painted with
white background and letters in black paint. The windrow marker should be
located in front of windrow after leaving the distance of movement of machines.
3. Leachate collection pits: MOC- RCC (M20) / brick work cement mortar
plastered (1:6). Size: not less than 1.5 meter X 1.5 meter having top level / free
board 300 mm above the ground level.
4. Leachate collection drain: MOC- RCC (M20)/brick work cement mortar
plastered (1:6). Size: 0.3 meter (width) X 0.25 (depth). The depth will increase
along the length towards collection pit. Bed slope: 1 in 200 approx. with smooth
finishing to prevent sludge (press mud) deposition on the base.
5. Floor lining: The floor lining shall be impervious, strong enough to prevent
settlements due to machine load. Minimum thickness 100 mm. The underlining
sheet shall be minimum 150 micron HDPE film below the floor. Clay layer cushion
of 300 mm below the liner and 50 mm above the liner should be provided. In
case of RCC flooring, the construction joint should be sealed using the water
bar/hot bitumen.
6. Ground water monitoring facilities.

a. Location of piezometer wells: Minimum at 4 places along the periphery

of the bio-compost yard such that one is in the upstream of the Ground water
flow direction and one in the downstream direction. For Bio-compost yard of
more than 5 acres area, one additional Piezowells shall be constructed for
every 5 acres and shall be in the downstream direction placed sufficient away
from each other to assess any seepage /ground water contamination tested
quarterly. (Example: for 20 acre Bio-compost yard the total number of
Piezowells shall be 4+3 =7nos. One upstream and 6 down steam uniformly
distributed). Piezo-wells shall be constructed as per the standard procedure
and specifications.
b. Hand pump: at least 30 meters depth, located within 500 meters to 1 Km
from yards. Water quality of hand pump should be tested quarter.

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7. Data recording: Log book at yard should be maintained mentioning the date of
formation of windrow, quantity of press mud, feed stock, date of last aero-trilling,
date of last spent wash spray, quantity of spent wash spray, temperature date-wise,
date of maturity, moisture content etc. Data should also be entered into the computer
for record and computation. The press mud and ready compost must be weighed and
records of the same shall be maintained.
8. Approach Road to bio-compost yard: The entrance of the Bio-compost yard
should be paved all- weather road for approach of vehicles.
9. Storage facilities for ready compost: Covered shed having platform.
10. Camera as per OCEMS guidelines shall be installed in the bio-compost yard to
monitor the bio- compost operations inside the shed.

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18.0 Bio-compost area calculation:

The requirement of Press mud depends on the size of the aerotilling machine that comes
in varying dimensions. Also, aerotilling machines comeswith side mounted turner and top
mounted turning machine. Further, the windrows require dressing with JCB machine after
every turning for which a spacing of 3 meters is required between each windrow.

The area of biocompost area required shall be calculated based on the followingsample
basis of calculation:
License capacity of distillery = 36,000 KL/Annum
Spent Wash generation = 9 KL/KL
Total Spent Wash generation = 36,000*9
= 3,24,000 KL
Concentrated Spent Wash@60% volume reduction = 1,29,600 KL/Annum

1.6 KL concentrated spent wash (CSW) is applied per MT of Press mud i.e., Press
mud: CSW = 1:1.6

Press mud requirement @ 1/1.6 MT/KL = 1,29,600/1.6

= 81,000 MT
The land requirement for press mud should therefore be designed based on the
windrow size following the sample calculation as below based on 850 MT/Acre/cycle of
press mud
No. of Cycle =4
Press mud/Cycle = 81,000/4 = 20,250 MT
Land Area Required = 20,250/850
= 23.8 Acres
No. of Cycle =5
Press mud/Cycle = 81,000/5 = 16,200 MT
Land Area Required = 16,200 /850
= 19.0 Acres

In case of specially designed aerotiller machine, bio-compost yard area will becalculated
as per the windrow size specification mentioned by the machine manufacturer.

Land requirement for press mud storage: Equivalent to one cycle

Land requirement for storage of ready compost: 15% of additional area (that of area
calculated for biocomposting process on the basis of material balance).

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19.0 Standard Operating Procedure (SOP) for Incineration
boiler operation for Molasses based distilleries

Incineration of Spent wash

Incineration of concentrated spent wash (55-60 °Brix) along with some subsidiary fuel
in a specially designed boiler is one of the potential technology for achieving Zero
Discharge of molasses based distillery effluent. Concentrated spent wash at about 55-
60 % solids is fired in boiler along with subsidiary fuel such as coal or bagasse or other
biomass. Either fluidized bed or travelling grate type of incineration boilers are in use.
They can run throughout year.

1. Distilleries with Incineration boiler shall be in operation throughout the year.

2. Boiler should have online continuous stack emission monitoring system
3. Online Continuous Mass flow meters for measurement of spent wash at the inlet
and outlet of the MEE should be installed with connectivity to SPCB and CPCB
server.
4. The slope carrying pipe line from MEE plant to Boiler feed tank should have On
line flow meters with data recording facility which should be transmitted online
to CPCB and SPCB shall be installed at the raw spent wash/whole stillage
generation line and the concentrated spent wash/whole stillage / thick syrup line
connecting to incineration boiler.
5. The supporting fuel i.e. bagasse, rice husk, coal, biomass etc. are to be stored
under a suitable covered area in order to avoid mixing of rain water.
6. The firefighting arrangement should be in operation in the area of fuel storage
area and boiler area.
7. Slop carrying pipeline should have proper heating element arrangement to avoid
spent wash choking in pipeline.
8. Concentration of spent wash in the range of 55-65% solids and then slop along
with supporting fuel may be burn in incineration boiler.
9. Moisture content of different types of supporting fuel should be minimum
approximately in the range as mentioned below:
Coal : 10 - 12 %
Rice Husk : 10 - 12 %
Bagasse : 48 - 50 %
Other Biomass : 10 - 15 %

10. When boiler is in operation and before put in operation the safety measures to be
taken are as follows,
a. Electrical supply to all prime mores such as ID & FD fans, water feed pump,
spent wash feed pump, ESP/Bag filter, coal feeder & Conveyor etc.

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 b. Generate & storage DM water as per requirement of makeup water.

c. Start the DCS system of boiler with all calibrated parameters.

d. Start DM water feed in the boiler as per the drum design level.

e. Keep ESP/Bag filter in operation.

f. Keep FBC/travelling grate/Reciprocating bed in operation.

g. Keep Fuel and ash conveyor in operation

h. Keep optimum staff for boiler operations, such as boiler attendant, water
attendant, fire man, DCS operator etc.

11. The operator must read all the instruction manual/operational manual of the
concern manufacturer of the boiler before start up and during operation of boiler.

12. Boiler warm up should be initiated by using coal/bagasse/fire wood/rice

husk/diesel.

13. Maintain the water level in the boiler drum.

14. The appropriate draught system should be maintained and monitored.

15. Maintain appropriate temperature of live steam, feed water, air, flue gas.

16. Maintain live steam pressure.

17. Following parameters to be maintained,

a. Bed temperature – 750 to 800 °C (as per instruction manual)

b. Draught at FBC/travelling grate as per design.

c. Hot air temperature as per design.

d. Boiler feed water temperature after de-aerator about 150 °C or as per design.
e. Slope brix, quantity, temperature as per design.

f. Ensure stack temperature should be in the range of 180 °C to 190 °C.

g. Ensure the Coal or other supporting fuel quantity and feed rate as per design
before cold start of the boiler
18. Initially the boiler will be started on supporting fuel such as coal/bagasse/rice
husk.
19. Switch on the slope feeding on bed using spray guns/atomizers.
20. Stabilize the operation & check the ratio of coal to slope or bagasse to slope. (for
coal base it can range between 25-30:70-75 (coal: slope) and for bagasse base
it can range between 35-45: 55-65 (Bagasses: slope))
21. Flue gas SPM should not more than 50 mg/m3 which should be monitored by

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 stack analyzer (real time/online continuous monitoring system connected to
SPCB & CPCB servers).
22. Ash collection will be through screw/belt conveyor from common silo and should
be disposed of as fertilizer or for any other use.
23. Proper record/log book of following consumption/generation should be kept
a. Feed water consumption, m3/h

b. Feed water analysis once in months

c. Chemical consumption if any MT/h for WTP or Boiler.

d. Slope consumption, MT/h

e. Live steam Flow, Pressure and Temperature.

f. Draft system Flow, Pressure and Temperature

g. Solid content of the slope (% Solid of the slope)

h. Supporting fuel consumption, MT/h

i. Steam generation, MT/h

j. Ash generation, MT/h

k. Boiler blow down generation, m3/h

l. Boiler working hours, h/day.

m. Boiler stoppage hours, h/day.

n. Cleaning time required, h/month. (Time duration between two cleaning)

o. Analysis of slope and supporting fuel being used in boiler (once in month)
24. Proper record of Ash generation & disposal should be kept;

Date Ash generated (MT) Ash disposed off Purpose of using Ash

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