Introduction to Air Pollutants B. Tech Chemical Engineering RTM Nagpur UNiversity

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Unit I
Environmental Pollutant
Dr. VIKESH G. LADE (Ph.D.)
Department of Chemical Engineering
Laxminarayan Institute of Technology, Nagpur
Rashtrasant Tukadoji Maharaj Nagpur University, Amravati Road, Nagpur – 440 033
Subject: BTCHE 602T (BCHE)
Environmental Engineering (Theory)

2. Topics of Unit I
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 2
 Sources & characterization of various pollutants.
 Concepts of biodegradability, biosorption,
biomagnifications.
 Measurement : COD, BOD, TOD, ThOD, soluble,
suspended, volatile solids, ammonical nitrogen.
 Mathematical model for BOD.
 Re-oxygenation and de-oxygenation in natural
purification process.

3. Learning Outcomes
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 3
When you have studied this session, you
should be able to:
1. Describe the main types of pollution.
2. Describe the sources of pollution and the way
pollutants reach the environment.
3. Describe the main characteristics of water
pollution
4. Describe the mathematical model for BOD

4. Environmental Pollutants
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 4
 Pollution is defined as the introduction into the
environment of substances liable to cause harm to humans
and other living organisms.
Pollutants may be in the form of gas, liquid, solid or energy.

5. Pathways of pollution
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 5
 The pathway of pollution is the way the pollutant moves
from the source, enters into the environment, and finally
how it reaches the human body or other recipient
 Once released into the environment, the worst effects of
many pollutants are reduced by one or more of the
following processes:
Dispersion – smoke disperses into the air and is no longer
noticeable away from the source.
Dilution – soluble pollutants are diluted in the water of a river
or lake.
Deposition – some suspended solids carried in a river settle
(are deposited) on the river bed.
Degradation – some substances break down (degrade) by
natural processes into different, simpler substances that are not
polluting.

6. Wastewater
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 6
 Sewage or wastewater is a dilute mixture of various wastes from residential,
commercial, industrial and other public places
Inorganic or mineral matter: ash, cinder, sand, grit, mud and other mineral salt
Organic matter: nitrogeneous and nitrogen-free
It is simply that part of the water supply to the community or to the industry which
has been used for different purposes and has been mixed with solids either
suspended or dissolved.
Wastewater is 99.9% water and 0.1% solids. The main task in treating the
wastewater is simply to remove most or all of this 0.1% of solids.
Wastewater contains
organic & inorganic
matters which may be
suspended, colloidal
& dissolved form.

7. Typical Wastewater Composition
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 7
Contaminants Unit Weak Medium Strong
Solids, total (TS) mg/L 350 720 1200
Dissolved, total (TDS) mg/L 250 500 850
Fixed mg/L 145 300 525
Volatile mg/L 105 200 325
Settleable solids (SS) mg/L 100 220 350
Fixed mg/L 20 55 75
Volatile mg/L 80 165 275
Settleable Solids mg/L 5 10 20
BOD5 , 200
C mg/L 110 220 400
Total organic carbon (TOC) mg/L 80 160 290
Chemical oxygen demand (COD) mg/L 250 500 1000
Nitrogen (total as N) mg/L 20 40 85
Organic mg/L 8 15 35
Free ammonia mg/L 12 25 50
Phosphorus (total as P) mg/L 4 8 15
Organic mg/L 1 3 5
Inorganic mg/L 3 5 10
Chlorides mg/L 30 50 100
Sulfate mg/L 20 30 50
Alkalinity (as CaCO3) mg/L 50 100 200
Grease mg/L 50 100 150
Total coliform no/100 ml 106
-107
107
–108
107
–109
Volatile organic compounds (VOCs) mg/L <100 100 -400 > 400

8. Effluent Standard for Disposal
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 8
Need of study of characteristics of wastewater ?
Information about strength, composition & characteristics of wastewater is
important in the design of treatment system & the amount of pollutants to be
removed up to prescribed level set by the local authority.

9. Characteristics of Wastewater
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 9
 The characteristics can be classified as:
1) Physical: i) smell or odour, ii) colour and iii) temperature iv) turbidity v)
solid content
2) Chemical: i) pH, ii) Chloride content, iii) Nitrogen Content, iv) fat, grease
and oil content, v) sulphites, sulphates and H2S gas, vi) dissolved Oxygen
vii) chemical oxygen demand viii) Biochemical oxygen demand
3) Biological characteristics relates to various micro-organism found in
wastewater
Characteristics depends on
1) Source of generation
2) Quality of water used
3) Culture of population
4) Conservation practice
5) Types of industries present
6) Treatment given by industries

10. Characteristics & Sources
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 10
Characteristic Sources
I Physical Characteristics/ Properties
i) Color Domestic and industrial wastes, natural decay of organic materials
ii) Odor Decomposing wastewater, industrial wastes.
iii) Solids Domestic water supply, domestic and industrial wastes, soil erosion, inflow infiltration
iv) Temperature Domestic and industrial wastes
II Chemical Characteristics
a) Organic:
Carbohydrates Domestic, commercial, and industrial wastes
Fats, oils, and grease Domestic, commercial, and industrial wastes
Pesticides Agricultural wastes
Phenols Industrial wastes
Proteins Domestic, commercial, and industrial wastes
Priority pollutants Domestic, commercial, and industrial wastes
Surfactants Domestic, commercial, and industrial wastes
Volatile organic compounds Domestic, commercial, and industrial wastes
Other Natural decay of organic materials
b) Inorganic:
Alkalinity Domestic wastes, domestic water supply, groundwater infiltration
Chlorides Domestic wastes, domestic water supply, groundwater infiltration
Heavy metals Industrial wastes
Nitrogen Domestic and agricultural wastes
PH Domestic, commercial, and industrial wastes
Phosphorus Domestic, commercial, and industrial wastes natural runoff
Priority polluter Sulfur Domestic water supply; doestic, commercial. And industrial wastes
c) Gases:
Hydrogen sulfide Decomposition of domestic wastes
Methane Decomposition of domestic wastes
Oxygen Domestic water supply , surface-water infiltration
III) Biological constituents:
Animals Open watercourses and treatment plants
Plants Open watercourses and treatment plants
Eubacteria/Archaebacteria Domestic wastes, surface water infiltration, treatment plants .
Viruses Domestic wastes

11. Decomposition of Sewage
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 11
 Most of the organic matter present in sewage is unstable and
decomposes readily through chemical as well as the biological
processes. The organic matter, which can be decomposed by bacteria
under biological action, is called biodegradable organic matter. Most
of the organic matter present in sewage is biodegradable and hence
undergo biological decomposition, which can be divided into
Aerobic decomposition also called aerobic oxidation.
Anaerobic decomposition also called Putrefactions.

12. Aerobic Decomposition
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 12
 Aerobic decomposition is caused by both aerobic bacteria as well as facultative
bacteria operating aerobically, in presence of air or oxygen which is available in the
wastewater in the dissolved form.
 These bacteria will then utilize the free oxygen as electron acceptor there by
oxidizing the organic matter to stable and unobjectionable end products.
 The stable end products like nitrates, carbon dioxide, sulphates, are formed,
respectively for the three forms of matter, i.e. nitrogenous, carbonaceous, and
sulphurous matter.
Water heat and additional bacteria will also be produced in the biological
oxidation, which can be represented by following equation
COHNS + Bacteria + O2 -------- CO2 + H2O + Bacteria + Energy
 The intermediate products formed in the aerobic oxidation of the three types of
organic matter can be known by studying nitrogen, carbon, and sulphur cycles.

13. Aerobic Decomposition
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 13

14. Anaerobic Decomposition
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 If free dissolved oxygen is not available to the sewage, then the anaerobic
decomposition, called putrefaction.
Anaerobic bacteria and facultative bacteria operating anaerobically, will then
flourish and convert the complex organic matter into simpler organic compounds
of nitrogen, carbon, and sulphur.
 These anaerobic bacteria survive by extracting and consuming like nitrate and
sulphates. Gases like ammonia, hydrogen sulphide, methane etc. are also evolved
in this decomposition, producing obnoxious (bad) odour.

15. Anaerobic Decomposition
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 15

16. Cycles of decomposition
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 The matter of the universe remains constant, but its form changes
because of biochemical reactions. The complex organic compounds
of biodegradable nature are broken up by biochemical reactions into
simple compounds which are consumed as food by plant and animal
life and the organic matter is formed again. This cycle thus goes on.
From the point of view of sewage treatment, the cycles of
decomposition of the following five elements are of importance:
1. Nitrogen cycle
2. Carbon cycle
3. Sulphur cycle
4. Calcium cycle
5. Phosphorus cycle.

17. Nitrogen Cycle
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18. Nitrogen Cycle
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 18

19. Carbon Cycle
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20. Carbon Cycle
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21. Sulphur Cycle
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22. Sulphur Cycle
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23. Phosphorus Cycle
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The phosphorus cycle relates to the maintenance of level of phosphorus in the soil.

24. Phosphorus Cycle
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 24
The phosphorus cycle relates to the maintenance of level of phosphorus in the soil.

25. Calcium Cycle
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 25
The calcium cycle relates to the maintenance of level of calcium in the soil.

26. Biomagnification
Dr. Vikesh G. Lade (Assistant Professor Chemical Engineering, LIT Nagpur) 26
 Biomagnification is the accumulation of a chemical by an organism
from water and food exposure that results in a concentration that is
greater than would have resulted from water exposure only and thus
greater than expected from equilibrium.
In aquatic environments, chemicals that are accumulated through
biomagnification may eventually become toxic to higher organisms as
well.
The lowest substrate concentration that is required to sustain
growth of a species is generally referred to as ‘threshold’
concentration.
In biodegradation, it is the lowest toxic substrate concentration
below which a microorganism cannot degrade the toxic substrate any
further.

27. Biomagnification
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28. Biosorption
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 Biosorption can be defined as the uptake of organic and inorganic
metal species, both soluble and insoluble, by physicochemical
mechanisms such as adsorption.
In living cells, metabolic activity may also influence this process
because of changes in the physico- chemical characteristics of the
cellular microenvironment.
Almost all biological macromolecules have some affinity for metal
species with cell walls and associated materials being of the greatest
significance in biosorption.
As well as this, cationic species can be accumulated by cells via
transport systems of varying affinity and specificity. Once inside cells,
metal species may be bound, precipitated, localized within
intracellular structures or organelles, or translocated to specific
structures, depending on the element concerned and the organism

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For any querry
Dr. Vikesh Gurudas Lade
Mob: 9712499555
email ID: dr.vikeshglade@gmail.com
Questions?