Distillery Spent Wash Treatment

8/10/2019 Distillery Spent Wash Treatment

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Introduction

Distillery effluent or spent wash (SW) is usually considered as waste of distillery processes

and can be classified as a dilute organic liquid fertilizer with high potassium content. Inrecent years, due to expansion of distilleries in sugar cane growing countries, the disposal of

SW has become an acute problem.

In India, about 15,000 million litres of spent wash is produced annually from 246 distilleries

which is characterized by undesirable color, foul odor, high biological oxygen demand (BOD:

5,0008,000 mg l1) and chemical oxygen demand (COD: 25,00030,000 mg l1).

Distillery Spent Wash Treatment


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The Need for Treating Distillery

Effluent

The distillery sector is one of the seventeen categories of major polluting industries inIndia. These units generate large volume of dark brown coloured wastewater, which is known

as spent wash.

The principal pollution effects of the wastewaters of these fermentation industries on a

water course are multiple in natures.

High temperature of the wastewaters may instantaneously kill fish and other aquatic

organisms, thus destroying the flora and fauna of a river, when the wastewaters aredischarged into it.

High concentration of readily decomposable organic matters present in the waste waters.

Due to decomposition of soluble and suspended organic matters present in the

wastewaters, high BOD (Biochemical Oxygen Demand) and COD (Chemical Oxygen

Demand) . Unfit for propagating fish life and for the purpose of drinking, personal hygiene, recreation

and other purposes.

The distillery effluents, when drained into a water source, make it susceptible for the

propagation of harmful microbes. Thus creating serious biological hazards like the

generation and propagation of the water borne diseases.


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IMPACT OF DISTILLERY EFFLUENT

ON ENVIRONMENT

Following are the impacts of distillery effluent on environment:

Discharge of wastewater with high TDS would have adverse impact on aquatic life and to

make unsuitable water for drinking purpose, if used for irrigation reduce the crop yield

,corrosion in water system and pipe line.

Suspended solids in wastewater reduce the light penetration and plant production as

a result in receiving water by increasing turbidity it can also clog the fish gills.

High amount of BOD in the wastewater leads to the decomposition of organic matter under

the anaerobic condition that produces highly objectionable products including Methane

(CH4), Ammonia (NH3), and Hydrogen Sulphide (H2S) gas.

Low Dissolved Oxygen (DO) in water bodies affect the aquatic life as DO drops fish and otherspecies are threatened and may get killed.

Fall in DO levels causes undesirable odours, tastes and reduce the acceptability of

water for domestic purpose.

In steam generation, DO is one of the most important factors causing corrosion of the boiler

material.


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MOLASSES WATER

DILUTER

YEAST PROPAGATION

FERMENTER FERMENTER SLUDGE

ANALYSER

RECTIFIER

ALCOHOL SPENT WASH

SPIRIT RECEIVER

EFFLUENT TREATMENT

ALCOHOL MANUFACTURING PROCESS AND NATURE OF DISTILLERY

WASTEWATER


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Alcohol Industry - Molasses and Grain Plants

Today

focus for multi feed plant

Grain & molasses

Installed basemajorlocations :

Maharashtra

UP

Karnataka Tamil Nadu

Punjab

368 units

192 units


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Today

Grain plants contribute

25% to total operating

base in India

Grain Plants - Major

Locations:

Maharashtra

Andhra Pradesh MP

Punjab

Alcohol IndustryInstalled Base

Figures in Million Ltrs

5.3 Billion Ltrs

1.9 Billion Ltrs


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Today

Standalone Distilleries =

34% of total molasses

base

Standalone unitsMajor

Locations:

Karnataka

Tamil Nadu Maharashtra

UP

Molasses Distilleries - Attached & Standalone

295 Units

192 Units


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Today

Grain plants contribute

29% to total alcohol

production in India

Grain Plants - Major

Locations:

Maharashtra

Andhra PradeshMP

Punjab

Alcohol IndustryProduction Growth


2.7 Billion Ltrs

1.0 Billion Ltrs


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Today

Thin Slop generation =

7 Ltrs/ Ltr of alcohol

S/W generation=8 Ltrs/ Ltr of alcohol

Adaptation of various ETP

solutions for s/w or thin

slop volume reduction

Alcohol Industry - Spent Wash Generation


15 Billion Ltrs

28.5 Billion Ltrs

1990- S/W quantity = 15 Ltrs/Ltrs of alcohol


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Alcohol IndustryFresh Water Requirement


34 Billion Ltrs

62.5 Billion Ltrs

1990- fresh water req. = 34 Ltrs/Ltrs of alcohol

Today

Fresh Water requirement=

18 Ltrs/ Ltr of alcohol for

molasses plant

Fresh Water requirement=

13 Ltrs/ Ltr of alcohol for

grain based plant

Reduce, recycle and reuseoptions for fresh water

requirement in distillery


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Distillery effluentscan be treated by a number of methods, either singly or incombination

The selection of the effluent treatment route is dependent upon:-

- Effluent characteristics (before treatment)

- Requirements of effluent characteristics (after treatment) for recycle

or disposal- Other factors :

operating economics

initial/capital cost

land and power requirement

ease of operations etc.

ETP OptionsSelection Criteria by industry


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Way Ahead...

Perfect existing waste water treatment technologies

Develop innovative technologies which will help to

operate ETP solutions in more economical way

Technology for reducing water footprint to greater extent

Contribute to environment by reducing GHG emissions

1

2

3

4


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Key Challenges Faced by Alcohol Industry

Key Challenges for Indian Distillery Industry

(1) Raw Material -

Shortage of molasses and grain

High prices of feedstock (especially in off-season)

Deteriorating quality of feedstockstarch or fermentable sugar

(2) Effluent Management

Effective handling of huge volume of spent wash

Operation during rainy season

Zero Liquid Discharge solutionsneed of more robust solution


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Present Treatment Process

Biomethanation to produce biogas.

Outlet of treated spent wash has following properties:

COD - 30000 - 35000 mg/lit

BOD - 5000 - 8000 mg/lit

Total solids 45000 mg/lit

Color 750000 IU

This is further taken for evaporation!


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Why Evaporation?

Spraying spent wash to pressed mud for composting is

allowed by pollution control board and is found to be the

legal way to dispose spent wash.

One factory, as an example produces 45000 MT pressed mud

by crushing about 10 lac MT cane

It has 60 KLPD distillery producing 800 m3 spent wash per

day for 300 days!

1kg pressed mud can absorb 2.5 liter spent wash, thus

volume must be reduced to less than 200 m3from 800 m3

per day


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The problem of color is not solved, in fact it is aggravated byconcentration

Such compost, when used in the field, is likely to leach the color

contaminating water bodies

Huge amount of precious energy is wasted for concentrating theproblem

Spent wash is highly corrosive; equipment used for

concentrating will have to be replaced in few years

Present process, unsolved issues:


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VM Biotech technology

for spent wash

Spent wash after treating in biogas digester is feed to this

Novel system.

The technology will produce water with parameters as

follows..

COD less than 10000 mg/lit

BOD less than 1000 mg/lit

Color less than 100 000 IU (Transparent yellow to

brown/red)

And 0.3% solids having about 3100 calorific value


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for spent wash

Treated spent wash can be safely used for composting

pressed mud that can absorb about 810 liter treated spent

wash per kg pressed mud

Thus entire quantity of treated spent wash is used forcomposting, no evaporation.

The composting will be complete as there are no inhibitors

present and will be of International standard and can be

sold at more than INR 8000 per MT


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for spent wash

Capital cost to treat 800 m3spent wash isabout INR 3.80 Cr

Cost of treatment of entire spent wash for yearis about INR 2.40 Cr

Color problem solved completely

No evaporation, thus Saves more than INR 20Cr per year

Separated solid can generate 4 MW Powerevery day

High Quality compost is bonus!


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VM BIOTECH Technology ..

Advantages.

Most enviro-friendly treatment process.

Low cost, yielding huge profits!

No water pollution from distillery

No evaporation, saves about INR 20 Cr

Good grade of treated water output.

It can be directly used for making internationalgrade compost fertilizer.

Problem of color solved completely. The process generates significant profit to treatpollution!

VM BIOTECH, Pune, INDIA


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VM Biotech technology, flexibility

Treated spent wash can be concentrated using MEV

or RO system to recover water

Finally solids, rich in potash can be recovered as

value added product Or concentrated liquid can be used for composting

VM BIOTECH, Pune, INDIA

Documents

Distillery Spent Wash Treatment