Environmental engineering

1. CHAPTER 2:
CHEMISTRY AND MICROBIOLOGY IN
ENVIRONMENTAL ENGINEERING
Contents of presentation:
i. Properties of water, air and soil
ii. Microbiology

2. Properties of water, air
and soil

3. ENVIRONMENTAL SCIENCE
Fundamental study of
chemistry, physics and
biology of the natural
system or environment

4. WATER CHEMISTRY
Physical Properties
Chemical Properties
Buffers

5. PHYSICAL PROPERTIES OF WATER
 In environmental science, the physical properties of water that relevant are density and
viscosity,
1) Density is expressed in three ways: Mass
i. Mass density, ρ = mass (kg)/unit volume (m-3) = M/V
ii. Specific weight of fluid,
γ =weight (force)/unit volume (m-3) by the acceleration of gravity (g = 9.81ms-2)
γ = ρ g
iii. Specific gravity, S= ρ = γ
ρ0 γ0
Water has a specific gravity equal to 1.

6. 2) Viscosity
 The viscosity of water at a temperature of 20 degrees Celsius
is approximately 0.01 poise or 10-3 Pa.s (Pascal seconds).
 Viscosity is a measure of the resistance of a fluid to
deformation at a given rate. For liquids such as water,
viscosity can be perceived as a measure of the liquid’s
resistance to flow.
 Therefore, it can be understood that the viscosity of honey
will be higher than the viscosity of water.

7. PROPERTIES OF WATER
Chemical Description
 The chemical description of water is H2O, which means
that water is formed by the combination of two
hydrogen atoms and one oxygen atom.
 Hydrogen atom weighs one-sixteenth of an oxygen
atom, thus in water molecule, 88.8% of weight is from
oxygen, while 11.2% belongs to hydrogen.

8. CHEMICAL PROPERTIES OF WATER
 Polarity
 Water as a Solvent
Hydrophylic ('Water Loving')
Hydrophobic ('Water Hating')
Molecules
 pH

9. CHEMICAL PROPERTIES OF WATER:
Polarity
 Polarity is ability of an element to attract
electrons. If the atoms that make up a
molecule have different electro
negativities, that differ substantially, they
attract electrons unequally, causing
polarity.
 Though overall water has a neutral
charge, it tends to be slightly positive on
the hydrogen side and slightly negative on
oxygen side

10. CHEMICAL PROPERTIES OF WATER
Water as a Solvent
 Water has the capacity to dissolve more substances
than any other liquid, thus, is called universal
solvent.
 The universal solvent quality enables water to take
other valuable minerals, nutrients or chemicals with
them wherever they go. The polar bonds in water
molecule make it a universal solvent.

12. CHEMICAL PROPERTIES OF WATER
Hydrophilic Compounds
 Substances dissolving readily in water are called
hydrophilic compounds.
 They consist of ions or polar molecules that use
electrical charge effects to attract water molecules.
 The water molecules surround these polar molecules
and carry them into the solution, thereby dissolving
them.

13. CONT….
 For example, ionic substances like sodium chloride
dissolve in water, as the positive sodium ions and
negative chlorine ions of sodium chloride get attracted
to the polar water molecules.
Hydrophobic Compounds
 Molecules with prevailing nonpolar bonds are the ones
that are mostly insoluble in water and are called
hydrophobic compounds.

14. CHEMICAL PROPERTIES OF WATER:
pH
 The pH of a chemical substance is determined by the amount of hydrogen
atoms in it.
 Thus, a chemical compound with high pH has higher number of hydrogen
atoms in its chemical composition and are called acids.
 Whereas compounds with lower pH contains lower number of hydrogen
atoms and are called bases.
 Pure water has a neutral pH of 7, which is neither acidic nor basic

15. The pH scale runs from 1
to 14,
 ph 1-6 refers to acidic
pH,
 pH 8-14 refers to basic
pH.

16. CHEMICAL PROPERTIES OF WATER:
Acids & Bases
 Substances that release hydrogen ions into solutions are called acids
H2O (l) + HCl (aq) ⇌ H3O++ Cl-
 Substances that reduce the number of hydrogen ions in solution are
called bases
H2O (l) + NH3 (aq) ⇌ NH4
+ + OH-

17. CHEMICAL PROPERTIES OF WATER
Buffers
A solution that resists large changes in pH when acid or
base is added or when solution is diluted
Example: solution containing a weak acid and its salt is
an example of a buffer
CO2(g) CO2 (aq) + H2O H2CO3
* H+ + HCO3
2H++ CO3
2-

18. ATMOSPHERIC CHEMISTRY
 Air is a mixture of a variety of gasses. The air in the
atmosphere consists of nitrogen, oxygen, which is the
life-sustaining substance for animals and
humans, carbon dioxide, water vapour and small
amounts of other elements (argon, neon, etc.).
 Higher in the atmosphere air also
contains ozone, helium and hydrogen

19.  The first layer of air, which is
located closest to the earth is called
the troposphere. This layer is 11
kilometres in height. When moving
up in the troposphere temperatures
fall six or seven degrees per
kilometre.
 Consequentially the weather on earth
is mainly determined by
circumstances within the
troposphere.

20.  The second layer of air above the troposphere is
called stratosphere. Temperatures stop decreasing
in the lower part of this layer. The temperature is
around -55 degrees Celsius here.
 In the higher stratosphere temperatures are rising
to zero degrees Celsius at forty-seven kilometres
above earth.

21.  The third layer of air is called the
mesosphere.
 This layer can be found over
fifty-two kilometres above the
earths' surface.
 The upper part of the mesosphere
is called the mesopause. Within
the mesosphere, temperatures are
decreasing once more.
Mesosphere temperatures are
around -90 degrees Celsius.

22.  The fourth layer of air, the
thermosphere is located over ninety
kilometres above earth.
Temperatures rise enormously in
this layer, causing the highest
temperature to be above one
thousand degrees Celsius.
 The density of air is very low in this
layer.

23. CHEMICAL PROPERTIES OF AIR
Gas Percentage by Volumea
Nonvariable gases
Nitrogen 78.08
Oxygen 20.95
Argon 0.93
Neon 0.002
Others 0.001
Variable gases
Water Vapour 0.1-~5.0
Carbon Dioxide 0.035
Ozone 0.000006
Other gases Trace
Particulate matter Usually trace
a
Percentages, except for water vapour are for the dry air
Source: McKinney and Schooch, 1996

24. SOIL CHEMISTRY
Definition of Soil
Chemical Properties of Soil

25. SOIL
Definition: Soil is a natural body comprised of
solids (minerals and organic matter), liquid, and
gases that occurs on the land surface, occupies
space,
Important for the production of food;
maintenance of carbon, nitrogen and phosphorus
balances and the construction of building
materials
Contains about 95% mineral and 5% organic
matter

26. CHEMICAL PROPERTIES OF SOIL
 Nutrition
 Salinity
 Soil pH

27. CHEMICAL PROPERTIES OF SOIL :
Nutrition
 Soils hold onto nutritional elements in a way similar to
the way they retain water; Positively charged nutrient
molecules, are attracted to the negative charges on the
soil particles. This is called adsorption.
 Clay retains more nutrients than coarser soils, just as it
holds more water, because of the greater surface area

28. CHEMICAL PROPERTIES OF SOIL :
Salinity
 Soils in arid regions, hold high levels of salt
 Low rainfall prevents leaching of salts, so they build up
in soils.
 Some fertilizers and amendments also can increase
salinity.

29. CHEMICAL PROPERTIES OF SOIL
Soil pH
 Most plants grow best in the range of 6.5 to 7.0, which is acidic, but only
slightly.
 The so-called acid-loving plants prefer lower pH, in the range of 4.0 to
6.0.
 Under 4.0, few plants are able to survive.
 Slightly alkaline soil is not harmful to most plants (except acid loving plants)

30. Microbiology

31. DIVERSITY OF LIVING THINGS
 Old taxonomy classified living organism into 5 kingdoms based on their
nutritional status
i. Animalia- commonly heterotrophic and digest their food within
specialized organs
ii. Plantae- capable of photosynthesizing their own food
iii. Fungi- use organic chemicals as a source of carbon (hetrotrophic);
they secrete enzymes capable of digesting organic chemicals and
absorb the predigested material
iv. Protista- organism that did not fit other four kingdoms. Most are
unicellular, all are aerobic and have mitocondria to perform cellular
respiration e.g Protozoa
v. Monera- prokaryotes, single-celled organisms. They are the
smallest, simplest organisms

32. MICROBIOLOGY
 A study on the micro organism which are
microscopic and unicellular organism
 Micro organism plays important role in
Environmental Engineering and Environmental
Science
 The difference between prokaryote and
eukaryote cell structure is the most important in
the living world.

33.  Through molecular techniques, microbiologist learned that there are two
groups of bacteria that are genetically and metabolically very different from
one another. So, Woese (1990) has proposed dividing them into the Bacteria
and Archaea (originally Eubacteria and Archaebacteria) on the supposition
that these have separate origins. This controversial arrangement is called the
three-domain system.
 Three domain classification system :
i. Bacteria- includes the true bacteria e.g. cyanobacteria and
enterobacteria
ii. Archae- ‘living fossils’ from the planet’s very early ages before the
Earth’s atmosphere contained oxygen
iii. Eukarya (eukaryota)- eukaryotics organism with a true nucleus and
wide range organism, from protists to human

34. ARCHAE
 Essentially living fossil, formed within a
billion years after the Earth was formed
 Not bacteria; their genes differ
significantly from bacteria
 Both bacteria and archae have smaller
rings of DNA called plasmids
 Cell membranes are formed from isoprene
chains; not from the same lipids like in
other organisms

35. BACTERIA
Shapes of bacteria
 Cocci
 Bacilli
 Spirilli (spiral shape)
Grows in distinctive
patterns
 In pairs : diplo-
 Clusters: staphylo-
 Chain: strepto-

36.  Cell wall made of
peptidoglycan; consist of
polymers of modified sugars
cross-linked with short
polypeptides (vary with sp.)
 Cell wall maintains the shape
of the cell, protects from harsh
environments and prevents the
cell from bursting in hypotonic
solutions

37. BACTERIA STRUCTURE
 Capsule- thin layer of polysaccharide which round the
bacterial cell. It allows the organism to attach to the host
and provides protection against defensive cell such as
white blood cell
 Pili—hollow hair like structures made of protein. It
enable pathogenic bacteria to attach to the body and
cause disease.
 Flagellum—thin and hair like structure used for
locomotion

38. CLASSIFICATION OF BACTERIA
(BASED ON TACTIC BEHAVIOUR)
 Bacteria is capable to taxis or move
towards or away from a stimulus,
phototaxis is ability of the organism to
respond toward the light.
 Chemotaxis- towards the chemical;
barotaxis pertains to pressure and
hydrotaxis is related to water

39.  Trophic is to describe the level of nourishment
 Photoautotrophic- photosynthetic organism that
obtain their carbon from inorganic sources and
energy from sunlight. This kind of bacteria is
common. E.g. cyanobacteria, green sulfur bacteria
and purple sulfur bacteria
 Chemoautotrophic- organism that use carbon dioxide
as a carbon source and obtain their energy by
oxidizing inorganic substances

40.  Heterotrophs-derive energy from breaking down complex
organic compounds generated by other organisms
◦ Photoheterotrophics bacteria use light as a source of energy. E.g.
purple nonsulfur bacteria and green nonsulfur bacteria
◦ Chemoheterotroph use inorganic or organic compounds as
energy sources, however they use only preformed reduced
organic chemicals as a source of carbon for cell synthesis. E.g.
Acinetobacter, Alcaligenes
◦ Also in this group are saprobes, organism that absorb their
nutrients by decomposing dead organic matter and parasites,
organism that obtain their nutrients from the bodily fluids of
living organism

41.  Aerobic- survive in oxygen rich environment
and use oxygen as the terminal electron
acceptor
 Obligate aerobes- survive only in the presence
of oxygen
 Primary end products of aerobic decomposition
are carbon dioxide, water and new cell tissue

42.  Anaerobes- can only survive in the absence of oxygen
 Sulfate, carbon dioxide and organic compounds serve as
terminal electron acceptors
 The reduction of sulfate results in the production of
hydrogen sulfide, mercaptans, ammonia and methane
 Major by-products are carbon dioxide and water
 Obligate anaerobes cannot survive in the presence of
oxygen
 Facultative anaerobes can use oxygen as the terminal
acceptor and under certain condition they also can grow
in the absence of oxygen

43.  By optimal temperature range in which they grow
 Psychrophiles- grow best at 150C to 200C but still can
grow at temperatures near freezing
 Mesophiles grow best at temperatures between 250C and
400C include those that live in the bodies of warm
blooded animals
 Thermophiles- temperatures above 500C at a temperature
that would denature key proteins in most organism

44.  Stenothermophilies grow best at temperatures above 500C but
cannot grow at temperature less than 370C
 Hyperthermophiles need more than 750C
 In order for bacteria to grow, a terminal electron acceptor must be
available
 All organism require the micronutrients carbon, nitrogen and
phosphorus, appropriate environment so as the trace metals and
vitamins

45. PROTISTS
Protozoa
- are single-celled, eukaryotic organisms.
 Flagellates
- Protozoans that have one or more flagella, which
move in a whiplike motion.
 Sarcodines
- More commonly known as amoebas
- Among the 40,000 species of unicellular
organisms .

46.  Ciliates
- There are more than thousand speciess in the
phylum Ciliophora. Many species of ciliates
are large and complex and they can grow
up to 0.1 mm in length.
 Sporozoans
- include those organisms in the phylum
Sporozoa, are non-motile.
-All are parasites and form spores during
some
point in their complex life cycle.

47. Algae
-photoautotrophic protists that contain
pyrenoids, organelles that synthesize and
store starch.
 Green Algae
-contain the same types of chlorophy11 and
are the same color as most true plants.
 Brown Algae
-thrive in cool, marine environments
 Red Algae
-commonly found in warm seawater.
 Diatoms
- The most abundant unicellular algae in the
oceans.

48. FUNGI
 Feed by releasing digestive enzymes that
breakdown complex organic chemicals into
forms that they can absorb
 Most are multicellular, yeasts are unicellular
 Some are parasitic such as that cause
ringworm
 Divided into 4 phyla:
◦ Chytridiomycota
◦ Zygomycota
◦ Ascomycota
◦ Basidomycota