Treatment scheme of waste water generated from dairy industry

1. TREATMENT SCHEME OF WASTE
WATER GENERATED FROM DAIRY
INDUSTRIES
PRESENTATION ON

2. CONTENTS
o Introduction
o Source of wastes
o Characteristics of waste water
 Physical Characteristics
 Chemical Characteristics
 Biological Characteristics
o Effluent standard given by CPCB
o Treatment Methods
 Physical Methods
 Chemical Methods
 Biological Methods
o Emerging Technology
o Flow Chart of waste water treatment
o By-products Recovery
o Utilization of by-products
o References

3. INTRODUCTION
 The dairy industry involves processing of raw milk into products such
as butter, cheese, yogurt, ice-cream, curd and milk powder.
 The unit operations involved in dairy industry are –
 The by-products of dairy industries are buttermilk, whey & their
derivatives.
 Wastewater from this industry contains high concentration of organic
material, suspended solids, BOD and COD values, nitrogen
concentrations, oil & grease.
1. Raw milk processing, reception and storage
2. Separation & Standardization
3. Homogenization
4. Pasteurization
5. Chilling
6. Packing and Storage.

4. SOURCE OF WASTES
• Rinsing and washing of bulk tanks or cans in receiving operations.
• Rinsing of residual product remaining in or on the surfaces of all
pipelines, pumps, tanks, vats, processing equipment & filling
machines etc.
• Washing of all processing equipment.
• Water-milk solids mixture discharged to drain during start up, product
changeover and shutdown of pasteurizers, heat exchangers,
separators, clarifiers, and evaporators.
• Sludge discharge from clarifiers.
• Fines from cheese and casein operations.
• Spills and leaks due to improper equipment operation and
maintenance, overflows, and incorrect handling.
• Waste of unwanted by-product (e.g. whey, butter milk)or spoiled
materials

5. CHARACTERISTICS OF WASTE
WATER
The three main characteristics of wastewater generated from dairy industry
are :-
1. Physical Characteristics:
PHYSICAL PARAMETERS DESCRIPTION
COLOUR The colour of the wastewater is usually
white which may turn dark grey or
black due to bacterial decomposition
under anaerobic conditions.
ODOUR The wastewater generated has an
unpleasant odour.
TEMPERATURE The temperature of wastewater is 17-25
degree Celsius.
pH 5.5-9.5
TURBIDITY High turbidity is seen due to presence
of suspended solids in wastewater.

6. 2. Chemical Characteristics:
CHEMICAL PARAMETERS DESCRIPTION
CHEMICAL OXYGEN
DEMAND(COD)
COD of dairy waste water is high (up to
12000 mg/L) due to high organic content
originating from the milk.
NITROGEN CONTENT The high N content originates from milk
protein which may be present in organic
form(protein, urea, nucleic acid) or in
inorganic form(nitrates/nitrites).
PHOSPHOROUS CONTENT P is present in inorganic form as
orthophosphate & polyphosphate.
SUSPENDED SOLIDS High level of suspended solids is due to
the presence of coagulated milk, cheese &
flavoring ingredients.
OIL & GREASE The concentration of oil & grease in the
waste water is more than 10 mg/L.
OTHER ELEMENTS Na , Mg , Ca , Ni is also reported.
Contd….

7. 3. Biological Characteristics:
BIOLOGICAL PARAMETERS DESCRIPTION
BIOLOGICAL OXYGEN
DEMAND(BOD)
Dairy waste water usually have high
BOD due to the presence of large amount
of organic matters. The effluent from
dairy industry has BOD up to 4500mg/L.
DISSOLVED OXYGEN(DO) DO values are from 0.38-1.42 mg/L in
wastewater. The lower value of DO is due
to higher BOD and COD value of waste
water.
Contd…

8. EFFLUENT STANDARD GIVEN BY
CENTRAL POLLUTION CONTROL
BOARD(CPCB)

9. TREATMENT METHODS
PHYSICAL CHEMICAL BIOLOGICAL
Screening
Grit Chamber
Skimming
Tank
Sedimentation
Chemical
Coagulation
Adsorption
Neutralizatio
n
Aerobic Treatment
Anaerobic Treatment
• Up Flow Anaerobic
Sludge Blanket
• Hybrid Reactor
Activated sludge
process, Sequence
batch reactor and
membrane
bioreactor.
Trickling filter
Rotating biological
contactors
Aerated
lagoons
Pond stabilization

10. PHYSICAL METHODS
1. Screening:
 It is the first step for wastewater treatment system.
 Screening devices consists of parallel bars, wire mesh or perforated
plates to intercept large floating or suspended material.
 The main purpose of screening is to remove solid materials that could:
 Cause damage to other process equipment.
 Cause reduction in efficiency of the whole system & contaminate
waterways.
Types of Screen Size Of Openings Applications
Coarse Screens >6mm Remove large solids, rags & debris.
Fine Screens 1.5-6mm Reduced fine solids present in primary
effluents.
Very Fine Screens 0.2-1.5mm Helps in removal of very fine particles.
Micro Screens 0.001-0.3mm Upgrade 2˚effluent to tertiary standards.

11. 2. Grit Chamber:
 They are long narrow tanks that are designed to slow down the flow so
that solids such as large organic particles, sands etc. settles out of the
water.
 Its main purpose is to-
(1) Reduce formation of heavy deposits in aeration tanks, aerobic digesters,
pipelines and channels.
(2) Reduce the frequency of digester cleaning caused by excessive
accumulations of grit.
TYPES OF GRIT
CHAMBER
DESCRIPTION
Horizontal Grit Chamber It is a particular basin posed along sewer system &
accurately designed in length & area to assure the flow
speed reduction at 0.30-0.50m/s.
It permits the heavier grit to settle down but carry organic
particles.
Aerated Grit Chamber
It consists of standard spiral flow aeration tank which
allows lighter organic particles to move out of water
streams.

12. 3. Skimming Tank:
 The tank is in the form of a long, trough-shaped structure. The tank surface is
made as large as possible, and the sides narrow down at a steep angle.
 To prevent heavy solids from settling in the bed, compressed air is blown through
the diffusers placed on the floor of the tank.
 When compressed air is circulated, the oily matters rise upward and are
collected in the side trough, from where they are removed.
 The waste water enters the tank from the inlet, all the oily matters are collected in
the trough. The outlet conduit is given such a slope that grit is swept up on its
slope and is removed out of the tank.
 Its main purpose is to remove oil, grease, and fats from the waste water.
Figure: Skimming Tank. Source(Online Image): https://cutt.ly/0ky7k9a

13. 4. Sedimentation:
 It is widely used unit operation in waste-water treatment which involves
settling of suspended material by gravity.
 It is used for the removal of-
a) Particles such as clay or silts
b) Particulate matter in the primary settling basin
c) Biological floc in the activated sludge settling basin
d) Chemical flow when the chemical coagulation process is used.
 Sedimentation takes place in a settling tank.. There are three main types
of a settling tank-
a) Horizontal flow
b) Solid Contact Clarifiers
c) Inclined Surface Basins
 All of these tanks are divided into four zones-
i. Inlet Zone- It main purpose is to spread the water flow across the total
inlet of the tank.

14. ii. Settling Zone- It is the largest portion of the sedimentation basin. In
this zone settling of suspended particles takes place.
iii. Sludge Zone- It is located at the bottom of the tank and provides a
storage area for the sludge before it is removed for additional
treatment or disposal.
iv. Outlet Zone- It controls the amount of water flowing out of the
sedimentation basin. A good outlet ensures that only well-settled
water leaves the basin and enters the filter.
ADVANTAGES DISADVANTAGES
Simple, low cost method to reduce
settleable solids.
Very fine suspended particles cannot
be removed by this method.
Removal of settleable solids can
reduce turbidity and makes water
more susceptible to other treatment
methods to reduce microbes.
Contd…

15. CHEMICAL METHODS
1. Chemical Coagulation:
 It helps in removal of very fine suspended particles present in wastewater
which are not removed by sedimentation.
 In this process chemicals (coagulants) are added to the water to bring the
non-settling particles together into larger, heavier masses of solids
called floc.
Chemical
Coagulants
Organic Coagulants
• Used for solid & liquid separation
and sludge generation.
• For example-Melamine
formaldehydes and Tannins (used
for absorption of oil & grease).
Inorganic Coagulants
• It is particularly effective on raw
water with low turbidity (total
suspended solids concentration).
• For example- Alum, lime, ferrous
sulfate, ferric chloride.

16.  Pros:
 Reduces BOD up to 70%.
 Aids the settling of finer colloidal particles and mineral contaminants.
 Cons:
 The addition of chemicals results in the production of a large volume of
sludge which is hazardous due to the nature of the constituents being
added.
 The volume and toxicity of the sludge can drive up disposal costs as its
not easily dewatered.
Figure: Illustration of the chemical coagulation process to remove colloidal pollutants.
Source: Carlos E. Barrera-Daz Patricia Balderas-Hernandez Bryan Bilyeu, in Electrochemical Water and
Wastewater Treatment, 2018.
Contd…

17. 2. Adsorption:
 It is a process where soluble molecules
(adsorbate) are removed by attachment to the
surface of a solid substrate (absorbent),
primarily by Van der Waals force.
 Its main purpose is to remove organic
materials including detergents and toxic
compounds.
 The most widely used adsorbent is activated
carbon, which can be produced by pyrolytic
carbonization of biomass.
 Activated carbon is a form of carbon
processed to have small, low-volume pores
that increase the surface area available
for adsorption.
 Activated carbon is of two types based on
their size:
i. Powdered Activated Carbon(<200 mesh)
ii. Granular Activated Carbon(>0.1mm)
Figure: Adsorption process.
Source(Online Image):
https://cutt.ly/skuqVb6

18.  Pros:
 It is easy to use.
 Helps in the removal of the heavy metals.
 It is used to remove chemicals that give objectionable odors or tastes to
water.
 Helps in reducing the COD of the wastewater.
 Helps in the reduction of total suspended solids present in the wastewater.
 Cons:
 Adsorption by activated carbon increases the cost of the process.
 Relatively requires high investment.
 Performance depends on the type of materials used.
Contd…

19. BIOLOGICAL METHODS
1. Aerobic Treatment:
A. Activated Sludge Process:
 It is used for treating industrial wastewaters using aeration and a biological
floc composed of bacteria & protozoa.
 The basic component of this process is:
 Aeration Tank
 Settling Tank
 Return Activated Sludge(RAS)
 Waste Activated Sludge(WAS)
 In dairy plant it is of two types:
 Extended Aeration
 Low-loaded Activated Sludge.
 Its main purpose is to oxidizes carbonaceous biological matter and
nitrogenous matter.

20.  Pros:
 It provides high treatment efficiency for BOD, COD, N &P.
 Cost of installation is low.
 Cons:
 Bulking of sludge can occur.
 Large areas of land needed for their operation.
Contd…
Figure: Activated Sludge Process.
Source(Online Image):
https://cutt.ly/kkr6JeD

21. B. Sequencing Batch Reactor(SBR):
 It is a modified form of activated sludge
process.
 The principle of SBR is same as that of
activated sludge process with one
exception: there is only one tank for
aeration and clarification.
 Pros:
 Enhances the removal of N, P & TSS.
 Has BOD removal efficiency of 80 -90%.
 Cons:
 High level of maintenance is required.
 Has low pathogen removal efficiency.
Figure : Various stages of SBR.
Source(Online Image) :
http://biodos.org/SBR_02.htm

22. C. Membrane Bioreactor(MBR):
 It is the combination of a membrane
process with the activated sludge
process.
 Its main purpose is to provide an
advanced level of organic and
suspended solids removal.
 Pros:
 Has high COD removal efficiency(90-
95%).
 Reduces BOD to <5mg/L and TSS to
<2mg/L.
 Cons:
 High operation and capital costs
(membranes).
 Membrane complexity and fouling.
Figure: Schematic representation of MBR.
Source: Fundamentals of Membrane
Bioreactors by Bradley LadewigMuayad
Nadhim Zemam Al-Shaeli.

23. 2. Anaerobic Treatment:
 Anaerobic digestion is a process by
which microbes are used in absence
of oxygen for stabilization of organic
matter by conversion to biogas.
 This process involves four stages:
 Hydrolysis
 Acidogenesis
 Acetogenesis
 Methanogenesis
 The three types of reactors used
are:
 Up Flow Anaerobic Sludge Blanket
(USAB)
 Hybrid Reactor
 Anaerobic Sequencing Batch
Reactor(ASBR)
Figure: Anaerobic digester.
Source(Online Image): https://cutt.ly/akoge4U

24. A. Up Flow Anaerobic Sludge Blanket (UASB):
 It is a single tank process. The wastewater enters the reactor from
the bottom, and flows upward.
 A suspended sludge blanket filters and treats the wastewater as the
wastewater flows through .
 The main components are:
 An influent distribution system
 Gas-solid separator
 Effluent draw off facilities.
 Pros:
 It has high COD removal efficiency(80-90%)
 Biogas production can be used as
a energy source.
 Cons:
 Constant source of electricity is required.
Figure: Schematic representation of
USAB.
Source(Online Image):
https://cutt.ly/ekurWP4

25. B. Hybrid Reactor:
 It is a combination of a UASB reactor
with an anaerobic filter.
 This combination is an advanced form
enabling improved solid retention time
in the treatment of waste water.
 It converts organic waste to
recoverable green energy.
 The waste sludge obtained is suitable
for land application as liquid fertilizer
due to high nutrient content.
 Pros:
 It removes 90% of BOD.
 It removes 70% of COD.
 Cons:
 High cost of equipment and process.
Figure: A hybrid reactor.
Source(Online Image):
https://slideplayer.com/slide/3411242/

26. EMERGING TECHNOLOGY
MICROFILTRATION
• It has a pore size of 0.1-
10 micron.
• It allows only dissolved
components to pass
through the membrane.
• It is used for bacteria &
spore reduction, fat
removal in milk
&whey, as well as for
protein & casein
standardization.
ULTRAFILTRATION
• It has a pore size of
0.002-0.1 micron.
• It allows most
dissolved components
& some non-dissolved
components to pass.
• It is widely used in
concentration of whey
protein concentration
and milk protein
concentration.
 Membrane Filtration

27. NANOFILTRATION
• It has a pore size of
0.001 micron.
• It allows predominantly
monovalent ions to pass
through the membrane.
• It is used for special
applications such as
partial demineralization
of whey, lactose-free
milk or volume
reduction of whey.
REVERSE
OSMOSIS
• It has a pore size of
0.0001 micron.
• It allows only water to
pass through the
membrane layer.
• It is used for
concentration or
volume reduction of
milk and whey, milk
solids recovery and
water reclamation.
Contd…

28. FLOW CHART OF WASTE WATER
TREATMENT
Primary
Clarifier
Secondary
Clarifier
Waste
activated
sludge
Aeration
Tank
Disinfection
Primary
sludge
To sludge
treatment &
disposal
INFLUENT
recycle
Activated
sludge
EFFLUEN
T
Air

29. BY-PRODUCT RECOVERY
 It is done by using cross-flow
ultrafiltration method (CFUF).
 In this method the feed is passed
through a membrane as a result the
solid gets trapped in the filter &
the filtrate is released at the other end.
 The principal advantage of this is that
the filter cake is washed away during
the filtration process, increasing the
length of time that a filter unit can be
operational.
 When whey waste is treated by CFUF,
lactose & salts get permeates through
the membrane. Protein is used as animal
& human food while permeate is used
for lactose preparation.
Figure: Cross-flow ultrafiltration.
Source(Online Image): https://cutt.ly/1kyE6Y9

30. UTILIZATION OF BY-PRODUCT
They can be used for the
production of bio-plastics like
polyhydroxyalkanotes.
They are used for the production
of organic acids like propionic
acid which is used as a
preservative for animal feed &
human food.
They are used as a carbon source
for the production of biofuels.

31. REFERENCES
 A. Allwyn Sundarraj, A. Angeline Rajathi, Simon Cruz Vishaal , D.
Rohit, M. Saran Prakash , A. Alexander Sam , S.S. Seihenbalg(2018).
Food biotechnology applications in dairy and dairy products. Journal
of Pharmacy Research,12(4),520-525.
 Preeti Birwal, Deshmukh G, Priyanka and Saurabh SP(2017).
Advanced Technologies for Dairy Effluent Treatment. Journal of
Food, Nutrition and Population Health,1:1.
 Aleksandar Kolev Slavov(2017). General Characteristics and
Treatment Possibilities of Dairy Wastewater – A Review. Food
Technology and Biotechnology ,55(1),14–28. doi:
10.17113/ftb.55.01.17.4520.
 Bharati S. Shete A and N. P. Shinkar(2013). Dairy Industry
Wastewater Sources, Characteristics & its Effects on Environment.
International Journal of Current Engineering and
Technology,3(5),1611-1615.