Unit 3POLLUTION FROM MAJOR
INDUSTRIES
P.MUTHURAMAN, V VCOE
POLLUTION FROM MAJOR INDUSTRIES
Sources, Characteristics, waste treatment flow sheets
for selected industries such as Textiles, Tanneries,
Pharmaceuticals, Electroplating industries, Dairy,
Sugar, Paper, distilleries, Steel plants, Refineries,
fertilizer, thermal power plants – Wastewater
reclamation concepts.
Textiles Industry
Textiles Industry
• Textile wastewater includes a large variety of dyes and
chemical additions that make the environmental challenge
for textile industry not only as liquid waste but also in its
chemical composition.
•Main pollution in textile wastewater come from dyeing and
finishing processes.
•These processes require the input of a wide range of
chemicals and dyestuffs, which generally are organic
compounds of complex structure.
•Water is used as the principal medium to apply dyes and
various chemicals for finishes.
•Because all of them are not contained in the final product,
became waste and caused disposal problems.
•Major pollutants in textile wastewaters are high
suspended solids, chemical oxygen demand, heat, colour,
acidity, and other soluble substances.
•Substances which need to be removed from textile
wastewater are mainly COD, BOD, nitrogen, heavy metals
and dyestuffs1,2
Textile mill uses cotton, wool or synthetic
fibers.
Waste water generated depends upon
type of fiber used.
The pollutants in the wastewater include
- The fibers used and
- Chemicals used in processing
Tannery IndustryIndustrial Waste
Treatment
Pharmaceutical Industry Waste Management System
Diary Industry Waste Management System
The dairy industry involves processing raw milk into
products such as consumer milk, butter, cheese, yogurt,
condensed milk, dried milk (milk powder), and ice
cream, using processes such as chilling, pasteurization,
and homogenization.
Typical by-products include buttermilk, whey, and their
derivatives.
Dairy industries have shown tremendous growth in size
and number inmost countries of the world .
Introduction
These industries discharge wastewater which is
characterized by high chemical oxygen demand,
biological oxygen demand, nutrients, and organic and
inorganic contents.
Such wastewaters, if discharged without proper
treatment, severely pollute receiving water bodies.
Dairy processing plants can be divided into two categories:
Fluid milk processing involving the pasteurization and
processing of raw milk into liquid milk for direct consumption,
as well as cream, flavored milk, and fermented products
such as buttermilk and yogurt.
Industrial milk processing involving the pasteurization
and processing of raw milk into value-added dairy products
such as cheese and casein, butter and other milk fats, milk
powder and condensed milk, whey powder and other dairy
ingredients, and ice cream and other frozen dairy products.
DAIRY PROCESSING
Raw Milk Collection, Reception and Storage
Separation and Standardization
Homogenization
Heat Treatment and Cooling of Milk Products
Milk and Dairy Product Production
• Milk production
• Cheese production
• Butter production
• Milk powder production
Packaging of Milk and Dairy Products
Diary Processing Activities
The first steps in preserving the quality of milk should be taken at the farm.
To achieve the best quality raw milk at intake, milking
conditions must be as hygienic as possible.
The milk must be chilled to below + 4oC immediately after
milking and be kept at this temperature during transport to
the dairy.
Raw milk is collected and transported to the processing plant
in stainless steel
Raw Milk Collection, Reception and Storage
Centrifugal separation and clarification is common in dairy
processing to ensure further processing of standard
products avoiding quality variations.
Standardization of the dry matter for fat, protein, and
lactose content of the milk usually takes place in the
production phase of most dairy products
Separation and Standardization
The aim of homogenization is to prevent gravity separation
of the fat in the product and to improve the syneresis
stability of mainly cultured products.
The homogenizer consists of a high pressure pump and
homogenizing valve driven by a powerful electric motor.
Homogenization
MILK PRODUCTION
The processes taking place at a typical milk plant include: receipt and filtration/clarification of the raw milk; separation of all or part of the milk fat (for standardisation of market milk, production of cream and butter and other fat-based products, and production of milk powders); pasteurisation; homogenisation (if required); deodorisation (if required); further product-specific processing; packaging and storage, including cold storage for perishable products; distribution of final products
BUTTER PRODUCTIONThe butter-making process, whether by
batch or continuous methods, consists
of the following steps:
preparation of the cream;
destabilisation and breakdown of the
fat and water emulsion;
aggregation and concentration of the
fat particles;
formation of a stable emulsion;
packaging and storage;
distribution.
CHEESE PRODUCTIONVirtually all cheese is made by coagulating milk protein
(casein) in a manner that traps milk solids and milk fat into a
curd matrix.
This curd matrix is then consolidated to express the liquid
fraction, cheese whey. Cheese whey contains those milk
solids which are not held in the curd mass, in particular most
of the milk sugar (lactose) and a number of soluble proteins.
•Milk receipt, pre-treatment and standardisation
•Pasteurisation
•Addition of starter culture
•Coagulation
•Extraction of whey
•Cutting and cooking of curd
•Salting
•Ripening
•Packaging
•Distribution
CHEESE PRODUCTION
MILK POWDER PRODUCTION The milk is preheated in tubular heat exchangers before
being dried.
The preheated milk is fed to an evaporator to increase
the concentration of total solids.
The solids concentration that can be reached depends
on the efficiency of the equipment and the amount of heat
that can be applied without unduly degrading the milk
protein.
The milk concentrate is then pumped to the atomizer of a
drying chamber.
In the drying chamber the milk is dispersed as a fine fog-
like mist into a rapidly moving hot air stream, which
causes the individual mist droplets to instantly evaporate.
Milk powder falls to the bottom of the chamber, from
where it is removed.
Fine milk powder particles are carried out of the
chamber along with the hot air stream and collected in
cyclone separators.
PACKAGING OF MILK AND DAIRY PRODUCTS
Packaging protects the product from bacteriological, light,
and oxygen contamination.
Liquid milk products may be packed in a beverage carton,
which is mainly paperboard covered by a thin layer of food-
grade polyethylene on either side.
Milk cartons for long-life milk have an additional layer of
aluminum foil.
Many other packaging materials are also used, ranging
from simple plastic pouches to glass bottles, PET laminates
and PVC bottles.
WASTEWATER GENERATION
The dairy industry is one of the most polluting of
industries, not only in terms of the volume of effluent
generated, but also in terms of its characteristics as well.
A chain of operations involving receiving and storing of
raw
materials, processing of raw materials into finished products,
packaging and storing of finished products, and a group of
other ancillary operations (e.g., heat transfer and cleaning)
will produce wastewater.
CHARACTERISTICS OF WASTEWATER Dairy wastewater contains milk solids, detergents, sanitizers,
milk wastes, and cleaning water.
It is characterized by high concentrations of nutrients, and
organic and inorganic contents.
Salting activities during cheese production may result in high
salinity levels.
Wastewater may also contain acids, alkali with a number of
active ingredients, and disinfectants, as well as a significant
microbiological load, pathogenic viruses, and bacteria.
Other wastewater streams include cooling water from utilities,
storm water, and sanitary sewage.
CHARACTERISTICS OF WASTEWATER
•The dairy industry generate on an average 2.5- 3.0 litres of
wastewater per litre of milk processed
•The effluents are generated from milk processing through milk
spillage, drippings, washing of cans, tankers bottles, utensil,
and equipment’s and floors.
•Process in the treatment of industrial effluent may consist of
any one or more of the following processes:
1. Equalization
2. Neutralization
3. Physical Treatment
4. Biological Treatment
EFFECTS WHEN WASTEWATER DISCHARGED TO LAND
Dissolved salts contained in dairy plant wastewater can
adversely affect soil structure if wastewater is used to
irrigate land.
Wastewater can also leach into underlying groundwater
and affect its quality.
High salt levels affect the type of vegetation that grow.
Over-irrigation may cause the underlying water table to
rise, resulting in further deterioration of surface soils and
vegetation.
EFFECTS WHEN WASTEWATER DISCHARGED TO SEWER The volume and organic load of wastewater from just one
dairy factory during peak season may well exceed the
township's domestic waste.
This may overload the sewage treatment plant, cause odors
and give rise to poor effluent quality.
Domestic wastewaters have a BOD5 concentration of about
250 to 300 mg/L but in peak season a large dairy factory could
be discharging two mega liters of wastewater at
BOD5 of 2,000 mg/L each day – the additional load on a
sewerage plant is equivalent to an extra 16,000 persons which
is very difficult to treat.
AVOIDING WASTE DURING LIQUID MILK PRODUCTION
Liquid milk production
may lead to the
generation of odour,
wastewater, noise and
solid waste.
Suggestions for avoiding
wastes during liquid milk
production are given in
Figure .
AVOIDING WASTE DURING BUTTER PRODUCTIONWays to prevent the build up of surface deposits include:
• minimisation of surface area
•·prevention of build-up of milk stone deposits
• maintenance of butter churns
•·correct preparation before filling
• not over-working the batch
To avoid spills, buttermilk collection facilities should be large
enough to hold all buttermilk discharged. Buttermilk should
be dried or used as animal feed and solids recovered from
butter wash water also may be sold as stock feed.
AVOIDING WASTE DURING CHEESE PRODUCTION
Making cheese generates a large volume
of by-products such as whey.
Waste reduction can be achieved by:
not overfilling cheese vats to stop curd
loss
completely removing whey and curds
from vats before rinsing
segregating all whey drained from
cheese
sweeping up pressings (particles)
screening all liquid streams to collect
fines.
AVOIDING WASTE DURING MILK POWDER PRODUCTIONIt is suggested that evaporators be operated to:
maintain a liquid level low enough to stop product boil-
over
run to specified length – excessively long runs with higher
than specified running rates lead to blocked tubes which not
only produce high pollution, but are difficult and time
consuming to clean
use effluent entrainment separators to avoid carry-over of
milk droplets during condensation of evaporated water
minimize air emissions by using fabric filters or wet
scrubbers.
REUSE AND RECYCLE
Many dairy plants have technologies in place for
recovering wastewater and/or for reuse in the dairy plant.
Reuse and recycling can considerably decrease the
volume of mains water required to operate the plant.
Reuse and recycling reduce the cost of both mains water
and wastewater disposal.
Fats, milk solids and minerals can also be recovered from
wastewater and recycled – either at the dairy plant or offsite.
Cleaning chemicals can also be recovered and reused on
site.
TREATMENT OF DAIRY EFFLUENT
The highly variable nature of dairy wastewaters in terms of
volumes and flow rates and in terms of pH and suspended
solid (SS) content makes the choice of an effective
wastewater treatment regime difficult.
Because dairy wastewaters are highly biodegradable, they
can be effectively treated with biological wastewater
treatment systems, but can pose a potential environmental
hazard if not treated properly.
TREATMENT OF DAIRY EFFLUENT
Sugar Industry
Z:\IWM\Sugar Manufacturing Video.FLV.mp3
Sugar-Manufacturing
Sugar Industry
•Sugar can be produce from beet or from sugar cane.
•In India sugarcanes are used, Europe –beet is used.
•The mills are typically operated for 4 to 8 months after the harvesting of sugar cane.
•Odour nuisance near the sugar mills is a very common phenomenon.
•Mill house: –Sugar canes are cut into pieces and crushed in a series of rollers to extract the juice in the mill house.
•Lime Treatment –The milk of lime is added to the juice and heated.
–When colloidal and suspended impurities are coagulated, most of colour is also removed during lime treatment.
–The coagulated juice is clarified to remove sludge.
–The sludge is further filtered through filter press and then disposed off as solid waste (press mud).
Manufacturing process
•Sulphitation process –The filtrate is recycled to process along with entire quantity of clarified juice.
–This juice is treated by passing sulphur dioxide gas through it. This is known as sulphitation process.
–Colour of juice is completely bleached out due to this process.
•The clarified juice is then preheated and concentrated in evaporators and vacuum pans. The partially crystallized syrup from vacuum pan known as ‘massecuite’ is transferred to the crystallizers.
•Crystallizers –In crystallizers complete crystallization of sugar occurs. The massecuite is then centrifuged to separate the sugar crystals from liquor. –The spent liquor is discarded as ‘black strap molasses’. –Sugar is then dried and bagged for transport. –The fibrous residue of the mill house, known as ‘bagasses’ is burnt in the boilers or may be used as raw-materials for paper products. –Black strap molasses is used as raw material in distilleries.
Sources of wastewater and characteristics
•The wastewater from mill house include the water used as
splashes to extract maximum amount of juice and those
used to cool the roller bearings.
–This wastewater contains high BOD due to presence of
sugar and oil and grease from machineries.
•The wastewater from occasional washing of filter cloths
(used for filtering the juice) though small in volume, contains
high BOD and SS.
•The water used for cooling in evaporators also
contributes as wastewater. The cooling water gets polluted
as it picks up some organic substances from the vapors of
boiling syrup in evaporators and vacuum pan.
–Although this water is recirculated it is required to be
discharged. This contributes to considerable volume of
waste and moderate BOD.
•Additional waste originates due to the leakages and
spillages of juice, syrup and molasses in different
sections, and also during handling of molasses. Washing of
floor (periodic) contributes a lot to pollution load. Though, it
is small in volume, strong in BOD concentration.
•Periodic blow-off of the boilers produce another
intermittent waste discharge. This is high in SS, low in BOD
and usually alkaline.
Characteristics of combined waste from sugar mill
•The sugar mill effluent decomposes rapidly after few hours
of stagnation.
•Rapid depletion of DO followed by anaerobic stabilization
of waste causes a secondary pollution of offensive odour,
black colour, and fish mortality.
•Usually situated in rural areas, hence no sewers are
available for discharge.
Effect of the waste on receiving water
•Pollution load in sugar mills can be reduced with better water and material economy practiced in plant.
•Recycling will reduce the volume of waste to great extent. e.g. volume of mill house waste can be reduced by recycling the water used for splashing.
•Dry floor cleaning and reducing quantity of floor wash water can reduce the volume of waste.
•Proper control of operation can reduce the pollution load e. g. overloading of evaporators and vacuum pans, extensive boiling of the syrup leads to loss of sugar through condenser water thus increase in volume and strength of effluent.
Treatment of the wastes
•COD/BOD ratio (approx. 1.6 - 2) makes it biodegradable wastewater. •Conventional aerobic treatment (ASP and TF) are not too efficient even at low organic loading rate.
•Due to seasonal nature of waste conventional treatment may not be economical.
•Anaerobic treatment (digestion and lagoon) can give > 70% to 90% efficiency. Effluent from anaerobic treatment can be treated by stabilization pond.
•Two stage biological treatments (anaerobic lagoon + stabilization pond) is common. Overall BOD > 90% can be removed.
•UASB reactor followed by waste stabilization pond is also effective
Paper and Pulp Industry
Z:\IWM\The Paper Making Process.mp3
Z:\IWM\Paper and Pulp Industry.pdf
DISTILLERIES
• Distilleries are basically Alcohol producing Industries.
• Alcoholic industries uses different grains, Malted
barley and Molasses as a raw material.
• According to the data of All India Distilleries
'Association About 1.6 Million kilolitres of alcohol are
produced in India per year by 309 distilleries.
DISTILLERIES
Depending on the type of raw material used Industries
are classified as:
1. Beverage Alcoholic Industries:
It uses Grains, Malted barley and Molasses as a
raw material.
2. Industrial Alcoholic Industries:
It uses Molasses as a raw material. Molasses
generated during the manufacture of sugar from cane or
beet. It is a waste product containing sugar, which can no
longer be extracted economically.
TYPES OF ALCOHOLIC INDUSTRY
It includes Three stages:
1. Dilution:
It involves dilution of the Molasses with water to 12-
20% sugar .
2. Acidification with sulphuric acid,
Fermentation with the help of yeast,
Saccharomyces,ceravisiae under controlled condition of
pH & Temperature and Nutrient supplementation with
Nitrogen and Phosphorus.
3. Multistage evaporation.
MANUFACTURING PROCESS
• Distilleries waste water is also known as Spent wash,
Slop, Vinnasse, dunder.
• It is one of the most Obnoxious waste.
• It has high B.O.D, C.O.D, Dissolved solids and low pH
• It can be profitable subjected to anaerobic treatment to
get gas(which has fuel value),followed by aerobic
treatment to meet discharge standards.
• It is amenable to biological treatment.
DISTILLERIES WASTE WATER
The first column of the train removes the bulk of water and other
constituent from the Ethanol and it is principal component of Spent
wash.
• The other waste water stream come from fermenter washing, floor
washing, cooling water, etc.
• It takes from 3 to 10 k.g of Molasses to produce 1 lt of alcohol and
produce 10 to 15 lt. of spent wash.
• The total volume of waste water per litre of Alcohol produce ranges
from 60 to 100 litres
• Cooling and Condenser waters are generally 6 times the volume of
Spent wash and are generally not polluted, as they are use in
surface condensers.
CHARACTERISTICS OF WASTE WATER IN MOLASSES DISTILLERY(GRAM PER LT.)
Spent wash is highly polluted, It is essential to adopt
measures such as :-
• Recycling: It reduces the volume of waste water to be
treated.
• Using in Irrigation: Spent wash, diluted 20times can be
safely used for the irrigation of sugarcane.
• Evaporation: It is done to produce animal feed or
fertilizers.
• Incineration: Incineration is done after evaporation, potash
can be recovered from the ash.
PRE-TREATMENT PROCESS
• On Land: Pollution of ground water, charring of vegetation
and crops, accumulation of salts and increase in Electrical
conductivity of Soil.
• Into water: Lowering pH(of receving water),Increase in
Organic load, Depletion of dissolved Oxygen, Large scale
fish kills, bad odors, discoloration of water.
EFFECTS OF DISCHARGE OF RAW SPENT WASH
Treatment of Waste Water is most efficient by
•Biological process
•Physico-Chemical methods, Sedimentation(plain
or Coagulants aid).
It leads to Anaerobic conditions and odors nuisance.
Treatment of Waste water is done by:
1. Anaerobic process
2. Aerobic process
TREATMENT OF WASTE WATER
• It includes:I. Fixed film bioreactors or non attached biomass reactor The composition of waste water for treatment by FFB is as:
ANAEROBIC PROCESS
Rectified sprit from distilleries waste water is treated by
Pilot Anaerobic Lagoon.
The composition of waste water for treatment by PAL is
as:
Pilot Anaerobic Lagoon:
The waste can be digested Anaerobically :
Retention time =12 days(B.O.D Loading rate
=11kg/metrecube/day) and
8days(6.12kg/metre cube/day).
-> Gas production is 124 metre cube/kg BOD destroyed.
• Cow dung is used as a Seed material
• Stable condition were established in 60days.
• At Organic loading of 0.6 kg BOD/metre cube/day BOD
reduction is 90-95% and Volatile solid reduction is 78%.
I. By Aerobic Cultivation of yeast on Spent wash
• It includes A Pure Culture of Saccharomyces cerevisiae is
adapt to the Spent wash.
• It is possible to adapt the culture to100% waste water
without addition of nutrients.
• The optimum pH was 5.0-5.5 and optimum inoculum dose
between 85 and 100 mg of dry yeast/70 ml of the waste.• Total sugar and BOD reduction is reduced up to 60% &57.5%.• In order to improve reduction Evaporation and Drying process can be used.
AEROBIC TREATMENT
Aim
• reduce the COD of the effluent
• to produce Acetic Acid.
• Acetic Acid is also a value added product. Process is done
in the range of following parameters:
II. Wet Air Oxidation:
• It is seen that Colour destruction is 95%.
• C0D reduction is 65%.
• Acetic acid is formed which can be recovered by
Conventional methods of Extraction.
REFINERY - INDUSTRY WASTE MANAGEMENT
Z:\IWM\Refinery Waste Treatment.pdf
FERTILIZER - INDUSTRY WASTE MANAGEMENT
Z:\IWM\Fertilizer Industry.pdf
STEEL - INDUSTRY WASTE MANAGEMENT
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