Table of Contents

PageContents i

Certificate iv

Candidate declaration v

Acknowledgement vi

List of Figures vii

List of Tables viii

Nomenclature ix

CHAPTER 1 Introduction

1.1 Background 1

1.2 Objective and Scope of Project Report 2

1.2 Organization of Project Report 3

CHAPTER 2 Introduction To Wastewater Treatment

2.1 Introduction - What Is Wastewater And What Is It Made Up Of? 4

2.2 Why Is It Necessary To Treat Human Waste Or Excreta 4

2.3 Deciding Which Treatment Option To Use 5

2.4 What Is Wastewater Treatment? 5

Levels Of Wastewater Treatment 7

2.6 Separation Of Solids 8

2.7 What Are Aerobic And Anaerobic Processes? 10

2.8 Sludge Accumulation 11

2.9 Elimination Of Nitrogen 11

2.10 Elimination Of Phosphorus 11

2.11 Elimination Of Toxic Substances 12

2.12 Removal Of Pathogens 12

2.13Conclusion 13

CHAPTER 3 Literature Review

3.1 Distillery Wastewater 14

3.1.1 Effect of Distillery Wastewater 15

3.1.2 Treatment of Distillery Wastewater 17

3.1.3 Zero Discharge of Distillery Wastewater 18

3.3 Membrane Technologies 19

3.2.1 The Growth of Membrane Technology 20

3.2.2 Component of membrane technology 20

3.2.3 Design Considerations 22

3.2.4 Type of Membrane Modules 22

3.2.5 Types of Membrane Technology 24

3.2.5.1 Pressure-driven membranes 25

3.2.5.2 Classes of pressure driven membranes 25

3.2.5.3 Electrically-driven membranes 28

3.2.6 Use of Membrane 29

3.2.7 Economic Importance of Membrane 30

3.2.8 Energy in Membrane Treatment Process 30

3.2.9 Problem with Membrane Technologies 31

3.3 Treatment of Distillery Using Wastewater Membrane Bioreactor 33

CHAPTER 4 Case study

4.1 Case Study on Microorganism for Distillery Wastewater Treatment 35

4.2 Improving Industrial Water Use 36

4.2.1 Water Balance 36

4.3 Case Study on Biofilteration 38

ii

CHAPTER 5 Summary 40

CHAPTER 6 References 41

iii

certificate

iv

candidate declaration

v

acknowledgement

vi

List of Figure

Page

Figure 2.1 Faecal-oral transmission 5

Figure 2.2 Composition of solids in raw wastewater. Source: Small

Wastewater System Operation and Maintenance 6

Figure 2.3: Treatment categorization and technologies 8

Figure 2.4 Schematic drawing of a stabilisation ponds system 9

Figure 2.5 Wastewater separation in a septic tank 9

Figure 2.6 Simplified illustration of Nitrogen cycle 12

Figure 3.1 Schematic production of distillery wastewater 16

Figure 3.2 Zero discharge system for distilleries 18

Figure 3.3 Process fundamental of membrane technology 19

Figure 3.4 Spiral membrane modules 24

Figure 3.5 Electrically driven membrane 28

Figure 3.6 Membrane bioreactors 34

Figure 4.1 Water balance 37

vii

List of Table

Page

Table 3.1 Typical characteristics of distillery spentwash 15

Table 3.2 Various membrane processes 22

Table 3.3 Characteristics of membrane modules 23

Table 3.4 Classes of pressure driven membranes 26

Table 3.5 Typical results of spent wash decolorization 27

Table 3.6 Economic importance of membrane 30

Table 3.1 Microorganism employed for the decolorization of

distillery effluent 35

viii

Nomenclature

BOD Biochemical Oxygen Demand

COD Chemical Oxygen Demand

CPCB Central Pollution Control Board

DWW Distillery Wastewater

EPS Extracellular Polymeric Substances

EDR Electrodialysis Reversal

MBR Membrane Bioreactor

MLSS Mixed Liquor Suspended Solids

MCABMembrane Coupled Anaerobic Bioreactor

MSW Molasses Spent Wash

MF Microfiltration

NF Nanofiltration

RO Reverse Osmosis

TSS Total suspended solids

TDS Total dissolved solids

TVS Total volatile solids

UF Ultrafiltration

ix

CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

The purification of waste water from various industrial processes is a world wide

problem of increasing importance due to the restricted amounts of water suitable for

direct use, the high price of the purification and the necessity of utilizing the waste

products. Maintaining the drinking water quality is essential to public health. Although

various water treatments is a common practice for supplying good quality of water from a

source of water, maintaining an adequate water quality throughout a distribution system

has never been an easy task. Municipal, agricultural and industrial liquid or solid wastes

differ very much in their chemical, physical and biological characteristics. The diverse

spectrum of wastes requiring efficient treatment has focused the attention of researchers

on membrane, ion-exchange and biological technologies. The most effective and

ecological technological systems developed during the past 20 years are as a rule based

on a combination of the chemical, physical and biological methods.

In recent years, membranes and membrane separation techniques have grown from a

simple laboratory tool to an industrial process with considerable technical and

commercial impact. Today membranes are used on a large scale to produce potable water

from the sea by reverse osmosis, to clean industrial effluents (distillery wastewater) and

to recover valuable constituents by electrodialysis. In many cases, membrane processes

are faster, more efficient and more economical than conventional separation techniques.

With membrane, the separation is usually at ambient temperature, thus allowing

temperature-sensitive solutions to be treated without the constituents being damaged or

chemically altered. There are two major types of waste inorganic waste and organic

waste. Organic wastewaters are potent sources of water pollution. Various organic

wastewaters that are known to cause serious problems may be attributed to distillery

effluents, pulp and paper effluents, textile effluents, and tannery effluents, among others.

1

Among these types distillery wastewater is highly charged with organic matter, when

dumped into water sources without treatment or with inappropriate treatment, causes

serious pollution. Among the raw material sources for distillery, two very important raw

materials are cane sugar molasses and beet sugar molasses. Molasses is a by-product of

the extraction process and is heavily used as a raw material in many distilleries around

the world. The discharge of wastewaters from wineries and distilleries is becoming

increasingly restricted as pressures from environmental regulations increase and as

awareness of the negative impacts of seasonal discharges of water containing high

nutrient and organic loadings into water courses spreads. Raw stillage discharge has a

highly deleterious effect on fish life. Stillage has been proposed for use as a fertilizer,

food supplement, biomass production agent, animal feed, and potash source (Pant et al.,

2007).

Municipal, agricultural and industrial liquid or solid wastes differ very much in their

chemical, physical and biological characteristics. There are various methods used in the

treatment of distillery wastewater. Physical-chemical treatment of distillery wastewater

has little success. This diverse spectrum of wastes requiring efficient treatment has

focused the attention of researchers on membrane, ion-exchange and biological

technologies. Anaerobic digestion, anaerobic filters, lagoons, activated sludge and

trickling filters have all been successfully applied to the treatment of distillery

wastewater. Membrane and membrane separation techniques with immobilized

microorganism or enzyme have very significant role in treatment of distillery wastewater.

1.2 Objective and Scope of Project Report

Now a day's wastewater treatment is not an easy task. For distribution of water to the

public it is necessary. The distillery wastewater has high amount of organic matter so

without treatment pull down in water stream is not ethical. Objective of my project report

is treatment of distillery wastewater using membrane technologies. The scope of my

project report is to first characterize the distillery wastewater and membrane technology,

then by these studies membrane techniques use for treatment of distillery wastewater.

2

1.3 Organization of Project Report

Firstly a full description of distillery wastewater which consist of composition of

distillery wastewater, source, effect, zero discharge system of distillery then about

membrane technologies which describe about membrane types, membrane modules, type

of membrane techniques, and also about how the membrane bioreactors are helpful for

treatment of distillery wastewater. Finally there are three case studies on microorganism

which are helpful for distillery wastewater and also about biofiltration how help in these

treatment processes.

3

CHAPTER 2

INTRODUCTION TO

WASTEWATER TREATMENT

2.1 Introduction - what is wastewater and what is it made up of? Human waste or more technically referred to as ‘excreta’ is defined by Chamber’s

Concise 20th Century Dictionary as “useless matter discharged by animal alimentary”,

animals being humans in this context. Excreta are made up of a solid matter, faces, and a

liquid matter, urine and are essentially an organic compound. The constituents making up

the compound are carbon, nitrogen, phosphorous, sulphur and hydrogen. Also present are

fats, carbohydrates, enzymes, proteins, trace elements, pathogens and many different

bacteria.

2.2 Why is it necessary to treat human waste or excreta?

It is necessary to treat human waste or excreta for many reasons, but the most important

reason is to preserve health. Untreated human excrement contains a variety of pathogenic

organisms, which include protozoa, bacteria, viruses and eggs of helminthes that are

disease-causing organisms. The presence of these in the environment transmits various

types of diseases. They could be:

• Water borne where pathogens are present in water supplies

• Soil–based where the excreted organism is spread through the soil

• Insect-vector borne where the pathogen is spread by insects that feed or breed in water

e.g. flies and mosquitoes.

• Faecal-oral transmission routes by which pathogens from faces reach the mouth by

either hand, clothes food etc.

4

Fig 2.1: Faecal-oral transmission

2.3 Deciding which treatment option to use. Once excrements have been produced, it is necessary to decide what to do with the waste

and determine the wastewater treatment option. There is a general distinction : Waste

being treated on-site via various treatment options e.g. VIP latrines, water seal toilets,

composting toilets etc. or by the use of water to carry the waste off-site to be treated

someplace else either not too far from the compound as with septic tanks or to specialized

treatment plants through sewer lines. This form of waste often is referred to as

wastewater or sewerage.

The total management of wastewater can be separated into four categories:

• Wastewater collection,

• wastewater treatment,

• treated wastewater disposal and,

• Sludge management.

Waste only becomes non-hazardous to human health after treatment.

2.4 What is Wastewater Treatment?

“The term treatment means separation of solids and stabilization of pollutants. In turn

stabilization means the degradation of organic matter until the point at which chemical or

biological reactions stop. Treatment can also mean the removal of toxic or otherwise

dangerous substances (for e.g. heavy metals or phosphorous) which are likely to distort

5

sustainable biological cycles, even after stabilization of the organic matter”. General

parameters to measure organic pollution.

COD (Chemical Oxygen Demand) is said to be the most general parameter to measure

organic pollution. COD describes how much oxygen is required to oxidize all organic and

inorganic matter found in the wastewater sample. BOD (Biological Oxygen Demand)

describes what can be oxidized biologically, with the help of bacteria and is always a

fraction of COD. Usually BOD is measured as BOD5 meaning that it describes the

amount of oxygen consumed over a five-day measurement period. It is a direct

measurement of the amount of oxygen consumed by organisms removing the organic

matter in the waste. SS (Suspended Solids) describes how much of the organic or

inorganic matter is not dissolved in water and contains settle able solids that sink to the

bottom in a short time and non-settle able suspended solids. It is an important parameter

because SS causes turbidity in the water causing clogging of filters etc. The mentioned

parameters are measured in 'mg/l'.

Fig 2.2 Composition of solids in raw wastewater. Source: Small Wastewater System

Operation and Maintenance

6

2.5 Levels of Wastewater Treatment Wastewater treatment options may be classified into groups of processes according to the

function they perform and their complexity:

Preliminary Treatment – includes simple processes that deal with debris and solid

material. The purpose of preliminary treatment is to remove those easily separable

components. This is usually performed by screening (usually by bar screens) and grit

removal. Their removal is important in order to increase the effectiveness of the later

treatment processes and prevent damages to the pipes, pumps and fittings.

Primary Treatment – is mainly the removal of solids by settlement. Simple settlement

of the solid material in sewage can reduce the polluting load by significant amounts. It

can reduce BOD by up to 40%. Some examples of primary treatment is septic tanks,

septic tanks with up flow filters, Imhoff tanks.

Secondary Treatment – In secondary treatment the organic material that remains in the

wastewater is reduced biologically. Secondary treatment actually involves harnessing and

accelerating the natural process of waste disposal whereby bacteria convert organic

matter to stable forms. Both aerobic and anaerobic processes are employed in secondary

treatment. Some examples of secondary treatment are UASB, reed bed systems, trickling

filters and stabilization ponds.

Tertiary treatment – is the polishing process whereby treated effluent is further purified

to acceptable levels for discharge. It is usually for the removal of specific pollutants e.g.

nitrogen or phosphorus or specific industrial pollutants. Tertiary treatment processes are

generally specialized processes. Some examples of tertiary treatment are bank’s clarifiers,

grass plots, etc.

The majority of secondary treatment processes are biological in their nature – i.e. they

use the natural activity of the bacteria to break down polluting material. Biological

treatment processes can themselves be divided into two general sub-divisions – aerobic

and anaerobic processes.

7

Advanced or quartiairy treatment are applicable only to industrial wastes to remove

specific contaminants.

Figure 3 gives an overview on technologies and their categorization

Figure 2.3: Treatment categorization and technologies

2.6 Separation of solids

Wastewater treatment also relies on the separation of solids, both before and after

stabilization. The choice of method of solid removal will depend on the size and specific

weight of pieces and particles of suspended solids.

Screening

For the larger pieces of solids for e.g. diapers, cloth, etc. in wastewater treatment. Screens

require cleaning at very short intervals. Materials captured through screening require a

safe place to be disposed of. Below is a diagram of waste stabilization ponds showing

screening as the first stage.

8

Fig 2.4 Schematic drawing of a stabilisation ponds system

Sedimentation

Separation of solids happens primarily by gravity, predominantly through sedimentation.

Coarse and heavy particles settle within a few hours or minutes while smaller and lighter

particles may need days and weeks to sink to the bottom.

Flotation

Flotation is the predominant method to remove fat, grease and oil. Unwanted flotation

occurs in septic tanks and other anaerobic systems where floating layers of scum are

easily formed. Accumulated scum could be removed manually or left purposely to seal

the surface of anaerobic ponds to prevent bad odour. Below is a diagram of a septic tank

showing scum floating on the surface.

Fig 2.5 Wastewater separation in a septic tank

9

Filtration

Filtration becomes necessary when suspended solid particles are to be removed that

cannot be forced to settle or float within a reasonable time. Most filters have a double

function, they provide a fixed surface for treatment of bacteria and they form a physical

obstacle for the smaller solid particles by creating adhesion of particles to their surfaces.

Filtration can be both on the upstream and the downstream. E.g. Upstream Anaerobic

Sludge Blanket. Anaerobic filters direct flow upwards through the filter material.

Trickling filters allow the wastewater to descend in a downward direction through the

filter material. The speed at which filtration occurs depends on the type of filter material

used. Smaller grain sizes and fine mesh sizes would cause filtration to be slower than

larger, wider-spaced material, but would cause the retention of many more solids and

clog faster.

2.7 What are aerobic and anaerobic processes?

With aerobic processes, bacteria use oxygen to feed on the organic material (which is a

food source) to produce carbon dioxide and water, with the production of quantities of

extra bacterial mass (sludge). Most aerobic processes require the mechanical addition of

oxygen and that can be expensive.

Anaerobic processes take place in the absence of oxygen and bacteria break down the

organic wastes to produce carbon dioxide and methane. This mixture of gases, called

Biogas, can potentially be harnessed as an energy source. Anaerobic process produces

much less excess sludge than aerobic processes however the treatment efficiency is not as

high as it is for aerobic processes.

The aerobic process happens much faster than anaerobic digestion and for that reason

always dominates when free oxygen is available. The high speed at which decomposition

occurs is caused by the shorter reproduction cycles of aerobic bacteria as compared to

anaerobic bacteria. Anaerobic bacteria leave some of the energy unused and it is this

unused energy which is released in the form of biogas. Aerobic bacteria use a larger

portion of the pollution load for production of their own bacterial mass compared to

anaerobic bacteria, which is why the aerobic process produces twice as much sludge as

10

the anaerobic process. Aerobic treatment is highly efficient when there is enough oxygen

available.

2.8 Sludge accumulation

Sedimentation and particles that escape filtration lead to sludge accumulation at the

bottom of vessels. This sludge gets compacted over time, consequently older sludge

occupies less volume than fresh sludge. Sludge removal is important and removal should

be performed as specified for each technology.

2.9 Elimination of Nitrogen

Nitrogen is a nutrient that causes algal growth in receiving waters and needs to be

removed from wastewater before discharge. It is also poisonous to fish in the form of

ammonia gases and also may become poisonous in the form of nitrite. The basic process

of nitrogen removal occurs in two steps, namely, nitrification (aerobic conditions)

followed by denitrification (anaerobic conditions) with the result that pure nitrogen

diffuses into the atmosphere. Nitrate is the most stable form of nitrogen and its’ presence

indicates complete oxidation.

2.10 Elimination of Phosphorus

Phosphorus is a nutrient that is water soluble, often recycled and is required to support

living plants and organisms. Bacteria cannot transform phosphorus into a form in which it

loses its fertilizer quality permanently. This implies that no appropriate biological process

either aerobic or anaerobic can remove phosphorous from wastewater. Phosphorus

removal from water normally takes place by removal of bacterial mass (active sludge) or

by removal of phosphate fixing solids via sedimentation or flocculation. This process is

normally performed in the tertiary stage of treatment.

11

Fig 2.6 Simplified illustration of Nitrogen cycle

2.11 Elimination of toxic substances

Most heavy metals are toxic or carcinogenic and therefore should not remain in the

wastewater because they harm the aquatic life of the receiving water or could enter the

human nutritious cycle when wastewater or sludge is used in agriculture. Since heavy

metals settle easy their removal is not difficult however soluble toxic substances may be

difficult to remove. There are numerous methods for converting toxins into non-toxic

substances for e.g. ion exchange procedures.

2.12 Removal of pathogens

Pathogens are present in many forms in excreta e.g. bacteria, viruses and protozoa and

accumulate in the sediment sludge and are largely retained inside the treatment system

where they stay alive for several weeks. Most bacteria and viruses caught in the sludge

die after shorter periods. Those bacteria, which are not caught in the sludge but remain

suspended in the liquid portion, are hardly affected, meaning, these bacteria and viruses

exit the plant fully alive. Exposure to UV rays has a substantial hygienic effect. High

pathogen removal can also be experienced in shallow ponds with long retention times.

12

Constructed wetlands with their multifunctional bacterial life in the root zones can also

be very effective. Using chlorination to kill pathogens is only advisable for hospitals in

the case of epidemics and other such special circumstances as chlorine kills all forms of

bacteria both beneficial and non-beneficial. Apart from this chlorine has an adverse

impact on the environment. Water is made unstable as chlorine itself has a high chemical

oxygen demand (COD).

2.13 Conclusion

Wastewater treatment involves a variety of processes performed at different levels of

treatment. The basic form of treatment is the breaking down of organic waste by bacteria

either aerobically or an aerobically or a combination of both which occurs in secondary

treatment. Primary treatment offers the settlement of solids. Tertiary treatment involves

the removal of phosphorus, nitrogen and toxic substances. Pathogen removal occurs

throughout treatment but becomes more effective mostly at tertiary levels through the use

of UV rays and chlorination. The higher the treatment efficiency the better the quality of

effluent produced.

13

CHAPTER 3

LITERATURE REVIEW

3.1 DISTILLERY WASTEWATER

Among the raw material sources for distillery, two very important raw materials are cane

sugar molasses and beet sugar molasses. Distillery wastewater (stillage) is the main

byproduct originating in distilleries, and its volume is approximately 10 times that of

ethanol produced. It is not surprising that the utilization of the stillage raises serious

problems, and that many attempts have been made all over the world to solve them.

Distillery wastewater is usually comprised of a high volume of greatly acidic matter

which presents many disposal and treatment problems. Waste streams generally contain

high levels of both dissolved organic and inorganic materials. There has been increasing

interest in the use of ethanol from biomass as a liquid fuel alternative. Ethanol

fermentation is examined in relation to distillery wastes. In the year 1999, there were 285

distilleries in India producing 2.7 × 109 L of alcohol and 319 distilleries, producing 3.25

× 109 L of alcohol generating 4 × 1010 L of wastewater each year. Generating a 40.4 ×

1010 L of wastewater annually. Reducing the volume of wastewater may be accomplished

by fermenting higher strengths of molasses (Basu, 1957).

To characterize distillery wastewater in detail so that proper insight may be gained in an

attempt to treat the waste to reduce the pollution hazards. Oxygen consumption values

can use to quantify the amount of organic matter present in wastewater (Basu, 1957).

However, considerable work has been reported in this field and should be taken into

account with the characteristics of distillery wastewater. Some of the work done on

distillery waste characterization by various parameters like: - pH, COD, BOD, phosphate,

total solids, total dissolved solids, total suspended solid, ammonia, sulfate, color and iron

etc as in the Table 2.1 (Saha et al., 2005).

14

Table 3.1 Typical characteristics of distillery spentwash (Saha et al., 2005)

Parameter Range

pH 3.8-4.4

Total solids (mg/L) 60000-90000

Total suspended solids (mg/L) 2000-14000

Total dissolved solids (mg/L) 58000-76000

Total volatile solids (mg/L) 45000-65000

COD (mg/L) 70000-98000

BOD (for 5 days at 200C) (mg/L) 45000-60000

Total nitrogen as N (mg/L) 1000-1200

Potash as K2O (mg/L) 5000-12000

Phosphate as PO4 (mg/L) 500-1500

Acidity as CaCO3 (mg/L) 8000-16000

Temperature (after heat exchanger) (0C) 70-80

3.1.1 Effect of Distillery Wastewater on Environment

To characterize distillery wastewater in detail, so that proper attempt to treat the waste to

reduce the pollution hazards. In a distillery, sources of wastewater are stillage, fermenter

and condenser cooling water and fermenter wastewater. The liquid residues during the

industrial phase of the production of alcohol are liquor, sugar cane washing water, and

from the cleaning of the equipment, apart from other residual water. This extract is

extremely polluting as it contains approximately 5% organic material and fertilizers such

as potassium, phosphorus and nitrogen. The amount of water used in this process is large,

generating a high level of liquid residues as in the Figure 2.1(Chang et al., 2003).

The effluents from molasses based distilleries contain large amounts of dark brown

colored molasses spent wash (MSW). The molasses spent wash (MSW) is a potential

water pollutant in two ways. First, the highly colored nature of MSW can block out

sunlight from rivers and streams, thus reducing oxygenation of the water by

15

Freeferementer

Distilled molasses Yeast

CO2

Analyzer column

Spent wash

Rec

tifyi

ng

colu

mn

Spent less

Alcohol55%

photosynthesis and hence becomes problem to aquatic life. Secondly, it has a high

pollution load which would result in eutrophication of contaminated water sources. Due

to the presence of putriciable organics like skatole, indole and other sulfur compounds,

the MSW that is disposed in canals or rivers produces obnoxious smell.

Figure 3.1 Schematic production of distillery wastewater (Chang et al., 2003)

In India, there is a number of large scale distilleries integrated with sugar mills. The

waste products from sugar mill comprise bagasse (residue from the sugarcane crushing),

pressmud (mud and dirt residue from juice clarification) and molasses (final residue from

sugar crystallization section). Bagasse is used in paper manufacturing and as fuel in

boilers, molasses as raw material in distillery for alcohol production while pressmud has

no direct industrial application (Pant et al., 2007).

Ethanol manufacture from molasses generates large volumes of high strength wastewater

that is of serious environmental problem. The effluent is characterized by extremely high

chemical oxygen demand (COD) (80000 to 100000 mg/L) and biochemical oxygen

demand (BOD) (40000 to 50000 mg/L), apart from low pH, strong odor and dark brown

color (CPCB 1994, 2003). In India, which is the second largest producer of ethanol in

Asia with annual production of about 2300 million liters in 2006–07 alcohol distilleries

16

are rated as one of the 17 most polluting industries. Other than high organic content,

distillery wastewater also contains nutrients in the form of nitrogen (1660 to 4200 mg/L),

phosphorus (225 to 3038 mg/L) and potassium (9600 to 17475 mg/L) that can lead to

eutrophication of water bodies. Further, its dark color hinders photosynthesis by blocking

sunlight and is therefore problem to aquatic life. Studies on water quality of a river

contaminated with distillery effluent displayed high BOD values.

3.1.2 Treatment and Disposal of Distillery Wastewater

During the 1970s, land disposal was practiced one of the main treatment options, since it

was found to enhance yield of certain crops. In Brazil waste generated from sugarcane

juice fermentation is mainly used as a fertilizer due to its high nitrogen, phosphorus and

organic content. It is use to increase sugarcane productivity and also under controlled

conditions the effluent is capable of replacing application of inorganic fertilizers.

However, for the high strength molasses-based spentwash, the odor, putrefaction and

unpleasant landscape due to unsystematic disposal are concerns in land application. In

addition, this option is subject to land availability in the vicinity of the distillery, also it is

essential that the disposal site be located in a low–medium rainfall area. More recent

investigations have indicated that land disposal of distillery effluent can lead to

groundwater contamination. Deep well disposal is another option but limited

underground storage and specific geological location limits this alternative. Other

disposal methods like evaporation of spentwash to produce animal feed and incineration

of spent wash for potash recovery have also been practiced (Sangave et al., 2006).

3.1.3 Zero Discharge of Distillery Wastewater

Worldwide environment regulatory authorities are setting for discharge of wastewaters

from industries. In India for instance, distillery industry had been told to achieve zero

discharge of spentwash by December 2005 according to the Central Pollution Control

Board as in the Figure 2.2 (CPCB, 2003). All methods of wastewater treatment such as

lagooning, biodegradation wet air oxidation bio-methanation, membrane filtration

17

Raw Spent wash

Evaporation Water for recycling into plant

Concentrate

Spray drying

Powder of high calorific value

evaporation composing were tried for last 25 years, and found to be techno-economically

nonfeasible. The present work proposes the process-engineering approach based on

experimental data on the same and similar fluid system. The process is experimented with

achievements like zero discharge of waste water, generation of distilled water to reuse in

process, conservation of system energy, self refinance on utilize like steam, water and

power. It further says that till 100% utilization of spentwash is achieved, controlled and

restricted discharge of treated effluent from lagoons during rainy season will be allowed

by CPCB in such a way that the perceptible coloring of river water bodies does not occur.

Figure 3.2 Zero discharge system for distilleries (CPCB, 2003)

18

Up-stream

Feed A + B

Concentrate Enriched in B

Permeate Enriched in A Depleted in B

Down-stream

3.2 MEMBRANE TECHNOLOGIES

Physical, chemical and biological treatment approaches have been employed for the

treatment of distillery wastewater. The physical methods are Sedimentation, Screening,

Aeration, Filtration (Membrane Technologies), and Flotation. The chemical methods are

Chlorination, Coagulation, Adsorption, and Ion Exchange. The biological methods are

grouped into two types. Aerobic methods are activated sludge treatment, lagoons,

trickling filtration, and oxidation ponds, and anaerobic methods are anaerobic digestion,

septic tanks (Water treatment method and disposal, 2009).

Municipal, agricultural and industrial liquid or solid wastes differ very much in their

chemical, physical and biological characteristics. This diverse spectrum of wastes

requiring efficient treatment has focused the attention of researchers on membrane, ion-

exchange and biological technologies. The most effective and ecological technological

systems developed during the past 20 years are based on a combination of the chemical,

physical and biological methods. The below Figure 2.3 explain all the fundamental of the

membrane technology; Feed enters into stream and by membrane separated into

concentrate and permeate (Weber, 1972).

Figure 3.3 Process fundamental of membrane technology (Weber, 1972)

19

The fact behind the membrane technology, works without the addition of chemicals, with

a relatively low energy use and easy and well-arranged process conductions. Membrane

technology is a generic term for a number of different, very characteristic separation

processes. These processes are of the same kind, because in each of them a membrane is

used. Membranes are now competitive for conventional techniques. Membrane filtration

can be used as an alternative for flocculation, sediment purification techniques,

adsorption (active carbon and sand filter), extraction and distillation (Pant et al., 2007).

3.2.1 The Growth of Membrane Technology

Membrane systems have been used in specialized applications for more than 30 years,

largely for water treatment (distillery wastewater), including desalination of seawater and

brackish water. With technical advances and corresponding cost reductions, membrane

systems are now capable of decontaminating waters (including treated wastewaters) in

single step processes at competitive costs. About two-thirds of the market will be for

water, and one-third for wastewater. Membrane technologies are receiving special

recognition as alternatives to conventional water treatment and as a means of polishing

treated wastewater effluent for reuse applications. Membrane technologies are energy

intensive. New membrane technologies feature the use of low pressure systems that

significantly reduce energy use and operation and maintenance costs (Satyawali et al.,

2008).

3.2.2 Components of a Membrane System

Typical membrane systems consist of various steps which are describe below:

(1) Pre-treatment

(2) Pumping

(3) Cartridge filtration

(4) Membranes and

(5) Post-treatment.

20

The effluent collected from the distillery industry is highly acidic with a pH range of

around 3. Hence, it is neutralized using sodium hydroxide. The neutralized solution has a

lot of suspended solids, so the filtration is carried out to remove the suspended particles

with a fine-pore thin cloth. This pre-filtrate is used as feed. Pretreatment of alcohol-

distillery wastes with ceramic membranes is performed prior to anaerobic digestion.

Ceramic membranes of different pore size are chosen based on the particle size

distribution in raw wastes. In some pretreatment, chemical oxygen demand (COD) is

reduced from 36000 to 18000 mg/L and suspended solids are almost completely

removed. Mixed stillage exhibited higher fouling tendency than pure naked barley

stillage. Several cleaning methods are attempted to recover water flux. Although lumen

flushing is effective, hydrogen peroxide proved to be the most effective cleaning agent.

The negative flux recovery after nitric acid cleaning could be explained by the ligand

exchange theory. The performance of digester is greatly improved with membrane

pretreatment, especially in the case of naked barley based stillage. Pretreatment may

include the addition of chemicals to prevent organic materials or soluble salts from

fouling the membrane (Ramkritinan, et al., 2005).

Pumping is required to raise the pressure to the desired operating level and to maintain

sufficient velocity across the membranes. A cartridge filter is nearly always provided by

the membrane manufacturer, usually for the removal of particles.

The filter provides protection against an upset in the pre-treatment step that could cause

fouling of the membrane. The membranes are the heart of the treatment system. They

may be hydraulically connected in series or parallel configurations, depending upon the

feedwater composition or desired water recovery. Post-treatment may include: (1) a

degasifier to remove carbon dioxide and - hydrogen sulfide and (2) the addition of lime

or caustic to prevent corrosion of the subsequent piping or distribution system (Weber,

1972).

21

3.2.3 Design Considerations

In addition to levels of constituent removal required factors to be considered in the design

of membrane systems include membrane life, membrane fouling, and disposal of

concentrate. Typical membrane life is three to five years depending upon the type of

service and type of membrane used. Membranes used in wastewater treatment typically

have a life of four to five years. For distillery wastewater, the normal life of a membrane

is three to five years, and many have been in service for more than six years (Weber,

1972). For various membrane processes different types of considerations are taken into

account, some are given below into Table 2.2.

Table 3.2 Various membrane processes (Weber, 1972)

Process Function Driving Force

Reverse Osmosis Selective solvent transport Pressure gradient

Electrodialysis Selective ion transport Electrical potential

gradient

Ultrafiltration molecular size, shape and

flexibility

Pressure gradient

Dialysis Selective solute transport Concentration gradient

3.2.4 Type of Membrane Modules

There are four basic type of membrane modules are found in the literature which are used

for various processes by doing some modification in these membrane modules. A basic

guideline for selecting the right module geometry for a specific application is depends on

following parameters as shown in the Table 2.3 (Genesis membrane, 2009).

22

Table 3.3 General characteristics of membrane modules (Genesis membrane, 2009)

Characteristics Spiral

Wound

Hollow

Fiber

Tubular Plate and

Frame

Typical Packing

Density

(ft2/ft3)

245 1830 21 150

Required Feed

Flow Rate

(ft3/ft2-s)

0.8-1.6 0.016 3-15 0.8-1.6

Feed Side Pressure

Drop

(psi)

43-85 1.4-4.3 28-43 43-85

Membrane

Fouling

High High Low Moderate

Ease of Cleaning Poor Poor Excellent Good

Recommended

Applications

Clean dilute

streams such

as water for

desalination.

Not good for

high

concentration

& fouling

chemicals

Very

clean

streams

such as

water.

For high conc.

in dirty

streams or

streams

containing

fouling

chemicals,

such as dye

desalting &

concentration

Laboratory

work and

membrane

evaluations.

Good for

high

viscous

liquids.

Two types of membrane configuration used extensively for distillery wastewater

treatment are hollow-fibre and spiral-wound. In a hollow-fibre element, fibers made of

porous polymer material are bundled together and sealed in a pressure vessel. For some

UF designs, feedwater enters through a perforated central tube and flows radially outward

23

through the fibre bundle. Under pressure, water is forced through the hollow-fibre bores

and exits through one or more ports. For RO, feedwater enters from the outside surface of

the fibre and product water is removed from the bores. Spiral-wound elements usually

range from 2 to 10 inches in diameter and 10 to 60 inches in length as in the Figure 2.4.

They consist of two flat membrane sheets separated by a thin, mesh-like porous support

or spacer and are sealed on three sides like an envelope. The fourth side is fixed onto a

perforated plastic centre tube that collects the product water. The membranes are rolled

up around the tube in the form of a spiral. Feedwater is pumped through the layers and

product water passes through the membranes and follows the spiral configuration to the

central perforated tube. Water that does not penetrate the membrane exits the element as

concentrate. Spiral wound elements are used for MF, UF, and RO (Lenntech, 2009).

Figure 3.4 Spiral wound membrane modules (Lenntech, 2009)

3.2.5 Types of Membrane Technology

24

The membrane separation process is based on the presence of semi-permeable

membranes. The principle is quite simple, the membrane acts as a very specific filter that

will let water flow through, while it catches suspended solids and other substances.

Membranes are typically made from polymeric materials, although ceramic and metal

oxide membranes are also available. Cellulose polymers are inexpensive and widely

used. More recent polyamide thin-film composite membranes are more chemically

robust, have longer life, possess greater rejection of dissolved salts and organics, and

operate at lower pressures. They are more expensive than cellulose membranes. Ceramic

and metal oxide membranes are traditionally used for UF and are commonly available in

tubular form. Although ceramic and metal oxide membranes are more costly than other

types, they are used for many industrial processes because they can withstand very high

temperatures. There are two basic types of membrane separation processes; pressure-

driven and electrically-driven (Nataraj et al., 2006).

3.2.5.1 Pressure-driven membranes

Pressure-driven technologies include, in order of decreasing permeability, microfiltration

(MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). MF and UF

often serve to remove large organic molecules, large colloidal particles, and many

microorganisms. MF performs as a porous barrier to reduce turbidity and colloidal

suspensions. UF offers higher removals than MF, but operates at higher pressures. In

wastewater reclamation, MF or UF might provide a suitable level of treatment. In

drinking-water treatment, MF or UF might be used in tandem with NF or RO to remove

coarser material so that fouling of the less permeable membranes is minimized. The most

commonly used process for the production of drinking water is RO, but NF is now

emerging as a viable alternative to conventional water treatment because it can operate at

lower pressures and higher recovery rates than RO systems. NF is also cost-effective in

many groundwater softening applications where the incoming turbidity is low

(Kalyuzhnyi et al., 2005).

3.2.5.2 Classes of pressure driven membranes

25

Pressure driven membranes have been classified into four categories based on the

membrane rejection properties as follows (Weber, 1972).

1) Microfiltration (MF) membranes: - have the largest pore size (0.1 to 3 micron),

require low transmembrane pressure (1 to 30 psi), and are used for turbidity

reduction, removal of suspended solids, parasites like bacteria and some viruses.

2) Ultrafiltration (UF) membranes: - have a smaller range of pore sizes than MF

membranes (0.01 to 0.1 micron) require low transmembrane pressure (1 to 30

psi), and are capable of removing viruses as well as some color, odor, and

organics removal, along with everything that the MF process can remove.

3) Nanofiltration (NF) membranes : - are relatively new porous membranes that have

a pore size less than 0.002 micron require moderate transmembrane pressure (75-

150 psi), and are primarily used for natural organic matter removal for controlling

disinfection byproduct precursor, water softening and sulfate removal.

4) Reverse osmosis (RO) membranes: - are effectively non-porous membranes that

require high transmembrane pressure (150-500 psi) and are used for monovalent

salt removal like Na+, K+.

Table 3.4 Classes of pressure driven membranes (Kalyuzhnyi et al., 2005)

Process Driving Force di (nm) Species Rejected

Microfiltration

< 50 nm

10-25 psi 100-

20,000

TSS, Protozoa,

Bacteria, Viruses

Ultrafiltration

2-50 nm

10-100 psi 2-10 Macromolecules,

Colloids, Proteins

Nanofiltration

< 2 nm

100-500 psi 0.5-2 Small molecules,

Hardness, Viruses

Reverse Osmosis

< 2 nm

100-1500 psi 0.3-0.5 NaCl, Mg2+, Ca2+,

SO42-, NO3-,Colour

Reverse osmosis technique generate about 50% clean colorless reusable water & the

balance 50% concentrate can be easily composted by available press mud. This method

26

thus creates an opportunity to arrive at zero discharge status. Thus it can be concluded

that the above mentioned specific membrane configuration has the distinct ability of

processing both the raw & biogas treated distillery spentwash, to obtain two streams, one

containing clear & colorless water & the other a concentrated spentwash. Their

quantitative proportion was average 50: 50. Thus the processing of the spentwash by this

technique offers an opportunity to reduce the volume by 50%, facilitating its convenient

composting. The overall press mud & land requirement also is reduced to 50%, thus

saving operating cost. The clear & colorless water may offer another opportunity to

recycle the same, which could be a great boon to distilleries operating in water scarce

areas or those spending large amounts of money for their water supply. Alternatively it

can simply be given to irrigation to benefit the farmers (Mohammad, et al., 2006).

Table 3.5 Results of spentwash decolorization by RO (Mohammad, et al., 2006)

Parameters Spentwash

INPUT

Color Black brown

Volume (L/hr) 450

Feed COD (ppm) 30000

Feed TDS Inorganic (ppm) 25000

OUTPUT

Color Colorless

Volume (L/hr) 225

Permeate COD (ppm) < 750

Permeate TDS Inorganic (ppm) < 1000

RECOVERY 50 %

3.2.5.3 Electrically-driven membranes

27

Electrodialysis reversal (EDR) is an improvement over the original electrodialysis

process. Electrodialysis reversal (EDR) is an electrochemical separation process that

removes ions and other charged species from water and other fluids. EDR uses small

quantities of electricity to transport these species through membranes composed of ion

exchange material to create a separate purified and concentrated stream. Ions are

transferred through the membranes by means of direct current voltage and are removed

from the feed water as the current drives the ions through the membranes. This

innovation improves both efficiency and the operating life of membranes. Ion exchange

membranes are the heart of the membrane process. Cation selective and anion-selective

membranes are alternately placed in a membrane. Distillery wastewater flows between

the membranes, and when direct current is applied across the stack of membrane, positive

ions move toward the cathode and negative ions move toward the anode as shown in

Figure 2.5 (Genesis membrane, 2009).

Figure 3.5 Electrically driven membrane (Genesis membrane, 2009)

3.2.6 Use of Membrane

28

As the cost of wastewater disposal increases, more emphasis is being placed upon the

recovery and recycling of the valuable chemicals contained within these streams.

Membranes are commonly used for the removal of dissolved solids, color, and hardness

in drinking water. Membrane technologies have also been proposed by the USEPA for

particle removal, reducing disinfection by-products such as trihalomethanes (THMs) and

haloacetic acids (HAAs) and eliminating illness-causing microorganisms such as Giardia

and Cryptosporidium in drinking water applications. In wastewater reclamation and

reuse, Water quality requirements may call for reductions in suspended solids, total

dissolved solids, and selected constituents such as nitrates, chlorides, and natural and

synthetic organic compounds. Membrane treatment, applied to the end of conventional

wastewater treatment systems, is a viable method of achieving desired effluent quality

levels at reasonable costs.

A hybrid nanofiltration (NF) and reverse osmosis (RO) pilot plant was used to remove

the color and contaminants of the distillery spent wash. The feasibility of the membranes

for treating wastewater from the distillery industry by varying the feed pressure (0–70

bar) and feed concentration was tested on the separation performance of thin-film

composite NF and RO membranes (Kalyuzhnyi et al., 2005). Color removal by NF and a

high rejection of 99.80 % total dissolved solids (TDS), 99.90 % of chemical oxygen

demand (COD) and 99.99 % of potassium was achieved from the RO runs, by retaining a

significant flux as compared to pure water flux, which shows that membranes were not

affected by fouling during wastewater run. The pollutant level in permeates were below

the maximum contaminant level as per the guidelines of the World Health Organization

and the Central Pollution Control Board specifications for effluent discharge (less than

1000ppm of TDS and 500ppm of COD).

3.2.7 Economic Importance of Membrane Technology

29

Engineers designing cross flow membrane equipment into process flow-sheets must

balance capital cost and operating expense just as they do for other process equipment.

For membrane equipment, the capital contributions and typical fraction of the total are as

in the Table 2.6(Weber, 1972).

Table 3.6 Economic importance of membrane technology (Weber, 1972)

Capital item % of total capital

Pumps 30

Replaceable membrane element 20

Housings for membranes 10

Pipes, valves and framework 20

Controls 15

Other 5

US membrane material demand will rise 8.2 percent annually through 2012, driven by on

going interest in higher purity process fluids and increasingly strict water/wastewater

quality rules. The best opportunities will emerge in pharmaceutical and medical markets,

while water and wastewater treatment remain the largest markets. This study analyzes the

$2.9 billion US membrane industry, with forecasts for 2012 and 2017 by type (e.g.,

cellulosic membranes, polysulfone and nylon membranes, ceramic membranes);

application (e.g., microfiltration, reverse osmosis, ultrafiltration); and market (e.g., water

and wastewater treatment, food and beverage processing, pharmaceuticals and medical

uses, chemical processing, industrial gas processing).

3.2.8 Energy Requirement in Membrane Treatment Process

Membrane processes use a significant amount of energy. Even low pressure membranes

use approximately 100 kwh per million gallons (3.785 million liters) of water produced.

The development of new composite membranes has reduced the operating pressures

considerably. Lower pressure operation means lower energy consumption.

30

3.2.9 Problems with Membrane Technology

Various type of membrane problem are occurs during operation of membrane the some

important specific membrane related problems such as membrane fouling, clogging,

scaling and cleaning.

Fouling of membranes can be broken into four distinct categories. They are fouling by

particulate matter, organic fouling, biological fouling, and inorganic scaling. Fouling with

particulate matter and suspended solids, If not properly dealt with, particulate matter and

fine suspended solids present in the feed water are problematic and will reduce the water

throughput of the membranes with time. Depending on the feed water quality, a filtration

system needs to be designed to reduce the influent suspended solids and particulate

matter before feeding the water. Fouling with organic materials, membranes are

susceptible to organic fouling depending on the source water quality. ED anion-exchange

membranes are particularly susceptible to organic fouling due to the negative charge

associated with natural organic matter. This can lead to process failures. Large organic

anions cannot penetrate the anion exchange membrane and will accumulate and adsorb to

the membrane surface, increasing the stack resistance. Small organic molecules can also

be problematic because they penetrate the membrane, but their electro mobility is low

and they remain inside the membrane. Fouling of this kind can make it quite difficult to

clean and restore these membranes to their original electrical resistance. NF and RO

membranes are fouled by organic adsorption as the membrane rejects these materials and

membrane permeates are produced. It is difficult to determine the organic fouling

potentials using aggregate organic measurements in the feedwater. Biological Fouling,

biofilm control is important in virtually every unit process, which sets out to accomplish

mass transfer in an aqueous system. Membrane manufacturers have come a long way in

reducing the biodegradability of the membranes themselves, but most modern RO and

NF membranes are sensitive to oxidants (Nataraj et al., 2006). Without the use of

oxidizing disinfectants, it is unlikely that biofilm control will ever be adequately

achieved. Although turbulent cross-flow is maintained in all membrane systems, bacteria

are still capable of adhering to the membrane surface and excreting extracellular

polymeric substances (EPS) to create a strong bond to the membrane surface. Once

31

attached to the membrane, a complex community of microorganisms is created that is

held together and fixed to the membrane with EPS. Biofilm result in decreased membrane

permeability in pressure driven applications and increased electrical resistance in

potential driven processes, increasing the operational and maintenance costs of

membrane processes. The rejection of targeted contaminants can also be adversely

affected. Fouling from the formation of inorganic scale, rejection of dissolved solids with

membranes segregates salts into a waste stream commonly referred to as concentrate or

brine. If the concentrations of these salts exceed their solution saturation, precipitates will

form a scale of inorganic salts (e.g. Fe2O3, CaCO3, CaSO4, SiO2, CaF2, BaSO4, etc.) on

the membrane surface. Scaling usually develops in the final stage of the RO or EDR

process at the membrane surface because this is the active point of ion separation where

concentrations are highest. By adjusting the feedwater recovery, the design engineer can

estimate the concentrations of the dissolved solids and specify a system that does not

suffer from inorganic scaling. Inorganic scaling, like other forms of fouling, will increase

the operational costs and require operator attention to clean and restore the membrane

system (Chang, et al., 2003).

Membrane fouling mechanisms during the longtime operation of a membrane coupled

anaerobic bioreactor (MCAB) system designed for the treatment of alcohol-distillery

wastewater. This system provided interesting information on anaerobic digestion and

membrane performance associated with the fouling mechanisms in the membrane

bioreactor. Enhanced COD removal was achieved with the complete retention of biomass

either inside the anaerobic reactor or on the membrane surface. Membrane fouling was

mainly attributed to external fouling, which was closely related to the movement of cell

population to the membrane surface and inorganic precipitation at the membrane surface.

There are two factors that determine the affectivity of a membrane filtration process;

selectivity and productivity. Selectivity is expressed as a parameter called retention or

separation factor. Productivity is expressed as a parameter called flux. Selectivity and

productivity are membrane-dependent.

3.3 Treatment of Distillery Using Wastewater Membrane Bioreactor

32

Membrane bioreactors (MBRs) are being increasingly recognized as an effective method

for the treatment of industrial (distillery) wastewaters. MBRs offer the advantages of total

solids retention at all biomass concentration, low sludge yield and better treated effluent

quality. In addition, the high mixed liquor suspended solids (MLSS) concentration

encourages the treatment of high strength wastewater. The widespread application of

MBRs is however, limited by two reason high initial membrane cost and progressive

membrane fouling, which leads to frequent membrane cleaning and eventual

replacement, thus contributing to the high operating costs. There are very few

investigations on distillery wastewater treatment in an MBR. The COD removal

efficiency was 94.7%. Membrane coupled anaerobic bioreactor (MCAB) using 0.2μm

polypropylene and 0.14 μm zirconia skinned inorganic tubular membranes has also been

investigated for the treatment of 40000 mg/L COD distillery wastewater at 55◦C. High

COD removal (90%) was observed in both the anaerobic MBRs as in the Figure 2.6

(Satyawali et al., 2008).

Anaerobically treated spentwash from sugarcane molasses based distilleries has a high

COD and requires further aerobic treatment. So the objective to investigate the optimum

start up method and continuous operation of aerobic MBR using anaerobically treated

spentwash as feed. The main objective behind using MBR was to provide long SRT

(sludge retention time) so that the degradation of high molecular weight compounds

could be achieved in the reactor. Nylon mesh was used instead of commercial

microporous membranes to decrease the cost. During MBRs study, the initial sludge

acclimatization phase where the focus was on biomass growth and sludge properties,

followed by continuous operation that mainly deals with reactor operation and filtration

performance (Gupta et al., 2008).

33

Bioreactor Membrane filtration

Air outlet

TreatedWater

Excess sludge

Aeration

Wastewater

Figure 3.6 Process of Wastewater Treatment Using Membrane bioreactors (Satyawali et

al., 2008)

34

CHAPTER 4

CASE STUDY

4.1 Case Study on Treatment of Distillery Wastewater using

Microorganisms

The microorganisms used for distillery wastewater treatment are given below which may

directly immobilized on the membrane or their enzyme is immobilized on the membrane

as in the Table 3.1 (Pant et al., 2007). Major finding of this work is the microorganism

used for decolonization is identified, which includes both bacterial and fungal

microorganisms.

Table 4.1 Microorganism employed for the decolorization of distillery effluent (Pant et

al., 2007)

Name Color Removal (%)

BACTERIA

Xanthomonas fragariae 76

Bacillus cereus 82

Acetobacter acetii 76.4

Pseudomonas pudita 60

Pseudomonas fluorescens 94

Pseudomonas aeruginosa 67

FUNGI

Trametes versicolor 82

Geotrichum candidum 80

Aspergillus niger 80

Mycelia sterilia 93

Rhizopus sp. 90

Aspergillus oryzae 75

35

4.2 Improving Industrial Water Use

Alcohol distilleries are highly water intensive units generating large volumes of high

strength wastewater that poses a serious environmental concern. This case study aimed at

identifying options for improved water use in this sector through a case study in a local

distillery. It emerged that optimization of cooling tower operation, innovative ways to

reuse wastewater streams like spent lees and spentwash and employing

semi-continuous/continuous fermentation could reduce water use in distilleries.

In general, reduction in industrial wastewater can be achieved through one or a

combination of the following measures.

1) Process modification or change in raw materials to reduce water consumption,

2) Direct reuse of wastewater,

3) In-plant reuse of reclaimed wastewater, and

4) Use of treated wastewater for non-industrial purposes.

4.2.1 Water Balance

The unit uses 1133.5 kilolitres water/day and generates around 668 kilolitre/day of

effluent. The effluent volume has been calculated on the basis of contributions from

water used for molasses dilution, yeast preparation, steam generation, fermenter washing

and effluent treatment. It has been assumed that other processes do not contribute to

effluent generation. Molasses dilution, cooling requirement and steam generation in the

boiler are the most water intensive processes. Thirty-four percent of total daily water

input to the distillery is in the form of cooling tower make-up volume that is a

consequence of evaporative loss, drift loss and blow down. Optimization of the cooling

tower operation and maintenance can contribute significantly to makeup water

requirement as shown in Figure 3.1 (Saha et al., 2005).

36

Figure 4.1 Water balance (Saha et al., 2005)

There is significant scope to improve water utilization in Indian distilleries through

conservation and reuse. Though good housekeeping measures such as proper metering of

water flow in individual units and maintenance of piping contribute to water savings,

specific interventions should also be targeted. Our study identified optimization of

cooling tower operation, innovative ways to reuse segregated wastewater streams and

replacing batch with semi-continuous/continuous fermentation to be appropriate

interventions to reduce water use in distilleries.

37

4.3 Case Study on Biofilteration

In common biological treatments, microorganisms are mixed with the waste material.

The microorganisms decompose the waste material and convert it to microbial biomass

and energy. There is no separation between the microorganisms and the treated waste.

One such treatment system is the activated sludge in waste treatment, in which the

microorganisms are suspended within the treated liquid. A second step of treatment is

needed in this system to separate the microbial biomass from the treated fluid. To

overcome from these problem biofiltration a technique is applied (Yariv, 2001).

Biofiltration is distinguished from other biological waste treatments by the fact that there

is a separation between the microorganisms and the treated waste. In biofiltration systems

the microorganisms are immobilized to the bedding material, while the treated fluid flows

through it. Recently, a vast amount of literature has been written on single experiments

involving the treatment of fluids by immobilized microorganisms. Several artificial

immobilization methods have been examined and impressive results have been achieved

in the treatment of fluids with one of the artificial immobilization methods - the

entrapment of microorganisms within polymer beads. This method, even though it needs

to be improved, seems to have a future potential in commercial biofiltration systems. The

methods of artificial immobilization of microorganisms within biofiltration systems have

several advantages, but also suffer from several disadvantages in comparison to the

treatment of fluids by naturally attached microorganisms. Understanding the mechanisms

and forces responsible for the attachment of microbes to the bedding material, in attempt

to improve this attachment is important. Further improvement of the artificial entrapment

of microorganisms within polymers will allow the exploitation of the advantages of this

method in the treatment of fluids. There are two methods of immobilization processes –

the self-attachment of microorganisms to the bedding material and the artificial

entrapment of microorganisms within polymer beads. Apart from the immobilization

process, biofiltration systems can be divided into two different treatment systems based

on the phase of the treated fluid, i.e., systems treating gas and those treating liquids.

38

There is a considerable difference in the operation of systems treating different phases of

fluid, even though based upon the same bedding material.

In biofiltration systems the pollutants may be removed from the fluid in several ways.

They can be adsorbed to the microbial film or to the bedding material. In biofilters

treating gas, the pollutants might be adsorbed to the water that clings to the bedding

material. The main way of pollutant removal in biofiltration systems, however, is the

biological degradation of the waste. In this way the contaminants are incorporated into

the microbial biomass or used as energy sources.

39

CHAPTER 5

SUMMARY

Drinking water quality is essential to public health. Although water treatment is a

common practice for supplying good quality of water from a source, maintaining an

adequate water quality throughout a distribution system is never an easy task. Municipal,

agricultural and industrial liquid or solid wastes differ very much in their chemical,

physical and biological characteristics. There are two type of waste like inorganic waste

and organic waste are potent source of water pollution. Organic wastewater that is known

to cause serious problems may be contributed by distillery effluent, pulp and paper

effluent and textile effluent etc. Among the raw material sources for distillery, two very

important raw materials are cane sugar molasses and beet sugar molasses. Distillery

wastewater is usually composed of a high volume of acidic matter which presents many

disposal and treatment problems. Waste streams of distillery wastewater generally

contain high levels of both dissolved organic and inorganic materials. There has been

increasing interest in the use of ethanol from biomass as a liquid fuel alternative. Ethanol

fermentation is examined in relation to distillery wastes. Reducing the volume of wastes

may be accomplished by fermenting higher strengths of molasses. There are various

methods used in the treatment of distillery wastewater. Physical-chemical treatment of

distillery wastewater has little success. Anaerobic digestion, anaerobic filters, lagoons,

activated sludge and trickling filters have all been successfully applied to the treatment of

distillery wastewater. This diverse spectrum of wastes requiring efficient treatment has

focused the attention of researchers on membrane, ion-exchange and biological

technologies. Membrane and membrane separation techniques with immobilized

microorganism or enzyme have very significant role in treatment of distillery wastewater.

40

CHAPTER 6

REFERENCES

Basu, A.K. (1975). “Characteristics of distillery wastewater”, Water Pollution Control

Federation, Vol. 47, pp. 2184-2190.

Chang, M.C., Tzou, W.Y., Chuang, S.H. and Chang, W.K. (2003). “Application of non-

woven fabric material in membrane bioreactor processes for industrial wastewater

treatment”, 5th International Membrane Science and Technology Conference, Sydney,

pp. 10-14.

Gupta, R., Satyawali, Y., Batra, V.S. and Balakrishnan, M. (2008). "Submerged

membrane bioreactor using fly ash filters: trials with distillery wastewater", Water

Science & Technology, Vol. 58, pp. 1281-1284.

Kalyuzhnyi, S., Gladchenko, M., Starostina, E., Shcherbakov, S. and Versprille, A.

(2005). “Combined biological and physico-chemical treatment of baker’s yeast

wastewater”, Water Science & Technology, Vol. 52, pp. 175-181.

Mohammad, P., Azarmidokht, H., Fatollah, M. and Mahboubeh, B. (2006). “Application

of response surface methodology for optimization of important parameters in

decolorizing treated distillery wastewater using Aspergillus fumigatus UB2 60”,

International Biodeterioration & Biodegradation, Vol. 57, pp. 195-199.

41

WEBSITEURL 1: http://www.iitb.ac.in/~cep/brochures/2007/dikshit-bro-07.html .

URL 2: http://www.lenntech.com/membrane-technology.htm .

URL 3: http://water.me.vccs.edu/courses/ENV149/methods.htm .

URL 4: http://www.p2pays.org/ref/09/08972.pdf .

URL 5: http://www.industrialeffluenttreatment.com/molasses-based-distilleries.html.

URL 6: http://www.genesismembrane.com/membrane_modules.html

42