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

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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

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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

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FERTILIZER - INDUSTRY WASTE MANAGEMENT

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STEEL - INDUSTRY WASTE MANAGEMENT