FATIH UNIVERSTY, ENVIRONMENTAL ENGINEERING DEPARTMENT
ENVE 101-Introduction to Environmental Engineering
Date: 15/10/20001
CHEMISTRY & MICROBIOLOGY IN ENVIRONMENTAL
ENGINEERING
CONTENT
Chemistry in Environmental Engineering
The Law of Mass Action
Attachment
Microbiology in Environmental Engineering
CHEMISTRY IN ENVIRONMENTAL ENGINEERING
Water Chemistry
Water has been called the universal solvent, and chemical parameters are related to the
solvent capabilities of water.
Total dissolved solids,
Alkalinity,
Hardness
Fluorides,
Metals,
Organics and nutrients are chemical parameters of concern in water-quality management.
An atom is the smallest unit of each of the elements.
For example: 2 hydrogen atoms combine to form a molecule of hydrogen gas.
A molecule is the smallest portion of a compound that can exist independently and retain its
properties. it is a complete chemical unit. While a molecule is often thought of as consisting
of more than one atom, this is not always true. For instance, helium has only one atom per
molecule. The oxygen molecule (O2) contains two atoms, as do chlorine (Cl2), hydrogen (H2)
and nitrogen (N2). Some molecules are huge having a molecular weight in the millions.
Macromolecules contain literally thousands of atoms. Some macromolecules must remain in
tact in order to retain their chemical entity. These are usually proteins. Polymers are chains or
networks of repeating sequences of chemical units known as molecules. Examples are
polypropylene or cellulose. Molecules of polymers can be broken without destroying the
chemical integrity.
The atoms that make up a molecule are either bonded together covalently, as in carbon
dioxide, or electrovalently, as in sodium chloride. However, in crystalline substances the
bonds extend throughout the whole crystal structure and the molecule has only a notional
existence. In covalent gases and liquids, however, the molecule actually exists as a small
group of atoms. The molecular formula gives the number of atoms of each element present in
the molecule; for example, the molecular formula of water is H2O and of carbon dioxide is
CO2.
The sum of atomic mass of all atoms in a molecule is the molecular mass of that molecule.
Atomic mass of hydrogen is 1
F. Karaca
FATIH UNIVERSTY, ENVIRONMENTAL ENGINEERING DEPARTMENT
ENVE 101-Introduction to Environmental Engineering
Atomic mass of oxygen is 16
What is the atomic mass of H2O?
A mole (in scientific measurement; symbol mol) is the SI unit of an amount of substance. This
amount of substance is a set number of atoms, molecules, or ions and is defined as the number
of atoms in 0.012 kg of the isotope carbon-12; it is equal to 6.022 x 1023, and is called the
Avogadro constant or number. This definition enables one mole of a substance to be simply
identified by mass. For example, 1 mole of hydrogen molecules (relative molecular mass 2)
has a mass of 2 grams, 1 mole of oxygen molecules (relative molecular mass 32) has a mass
of 32 grams, and so on. The molarity of a solution is a measure of its concentration in moles
of solute per litre of solvent.
Molar solution is a solution in which the number of grams of dissolved substance per litre
equals its molecular weight, i.e. a solution of molarity 1 M. A Molar solution (M) is a solution
that contains 1 mole of solute in each litre of solution. A mole is the molecular weight (MW)
expressed as grams (sometimes referred to as the ‘gram molecular weight’ (gMW)).
Therefore, 1 M = 1 gMW of solute per litre of solution.
For example, how much sodium chloride is needed to make 1 litre of a 1 M solution?
First, we find out the molecular weight (MW) of sodium chloride....
The chemical formula for sodium chloride is NaCl. In simple terms, this means that a
‘molecule’ of sodium chloride contains one sodium atom and one chlorine atom.
The atomic weight of sodium (Na) is 23.
The atomic weight of chlorine (Cl) is 35.5
So the molecular weight of sodium chloride (NaCl) is:
Na (23) + Cl (35.5) = NaCl (58.5)
Therefore, a 1 M solution of sodium chloride contains 58.5 grams of sodium chloride in 1 litre
of solution.
Similarly, a 2M solution contains 117 grams of sodium chloride per litre (MW x 2).
And, a 0.1M solution contains 5.85 grams/litre of sodium chloride (MW x 0.1).
Ion: an atom that has gained or lost one or more electrons and thus has either a positive
(cation) or negative (anion) charge.
Some compounds, called radicals, also possess charges.
For example:
Ammonia NH4+ cationic radical,
Carbonate CO32- is an anionic radical.
The equivalence of an element or radical is defined as the number of hydrogen atoms that
element or radical can hold in combination or can replace in reaction.
An equivalent of an element or radical is its gram molecular mass divided by its equivalence.
Example 2.1
F. Karaca
FATIH UNIVERSTY, ENVIRONMENTAL ENGINEERING DEPARTMENT
ENVE 101-Introduction to Environmental Engineering
How many gram of calcium will be required to combine with 90gr of carbonate to form
calcium carbonate?
CO3-2: Carbonate, C: 12 with +4 valance, Ca: 40 with +2 valance, O: 16 with –2
valance.
The Law of Mass Action
The law of mass action is universal, applicable under any circumstance. However, for
reactions that are complete, the result may not be very useful. We introduce the mass action
law by using a general chemical reaction equation in which reactants A and B react to give
product C and D.
a A + b B --------> c C + d D
where a, b, c, d are the coefficients for a balanced chemical equation.
The mass action law states that if the system is at equilibrium at a given temperature, then the
following ratio is a constant.
[C]c [D]d
------------- = Keq
[A]a [B]b
The square brackets "[ ]" around the chemical species represent their molar concentrations.
This is the ideal law of chemical equilibrium or law of mass action.
Equilibrium Expressions
The mass action law gives us a general method to write the expression for the equilibrium
constant of any reaction. At this stage, you should be able to write the equilibrium expression
for any reaction equation. If you are not sure from the above general theory, here are some
examples. It is more important for you to understand WHY the equilibrium constants are
expressed this way than what is the equilibrium expression.
Example 2.2
Write the the equilibrium constant expression for the reaction equation:
NH3 + HOAc = NH4+ + OAc-.
Hint
[NH4+] [OAc-]
--------------------- = K
[NH3] [HOAc]
(unitless constant)
Example 2.3
Determine the cencentration of Mg+2 and OH- at equilibrium. The solubility of products
of Mg(OH)2 is [Ksp] is 9x10-12
Hint
F. Karaca
FATIH UNIVERSTY, ENVIRONMENTAL ENGINEERING DEPARTMENT
ENVE 101-Introduction to Environmental Engineering
(solved in lecture) an please see the attachment which is the table of the solubility of products
Example 2.4
For the ionization of an acid, H2SO4 = 2 H+ + SO42- what is the equilibrium constant
expression?
Example 2.5
For the reaction equation: Cu2+ + 6 NH3 = Cu(NH3)62+ what is the equilibrium constant
expression?
MICROBIOLOGY (BIOLOGY) IN ENVIRONMENTAL
ENGINEERING
Biological processes are critical to environmental engineers concerned with wastewater
treatment, subsurface remediation, fate of chemicals in the environment, and pollution
prevention.
Current teaching and research emphases are:
 fundamental understanding of the biological processes which control the fate and
treatment of pollutants in natural and engineered systems;
 bioremediation of subsurface environments;
 modeling aerobic and anaerobic biological processes in order to estimate the rate of
oxygen transfer, carbonaceous oxygen demand removal, and nutrient removal;
 modeling the fate of organic chemicals and metals during conventional wastewater
treatment; and,
 development of data bases and predictive methods for biodegradation rate constants
and other important environmental properties.
Water may serve as a medium in which literally thousands of biological species spend part, if
not all, of their life cycle.
Aquatic organisms range in size and complexity from the smallest single-cell microorganism
to the largest fish. All members of the biological community are, to some extent, waterquality parameters, because their presence or absence may indicate in general terms the
characteristics of given body of water.
Most of the organisms of significance in natural purification processes are bacteria, algae and
protozoa.
Bacteria
Bacteria are a large group of microorganisms, mainly unicellular, that constitutes one of the
five major groupings (kingdoms) of living organisms, the Prokaryotae (or Monera). They are
characterized by a nuclear region without a bounding membrane, a single chromosome
formed into a ring, and the lack of mitochondria. Bacterial cells may be spherical, rod-like, or
spiral, or individual cells may collect as filamentous colonies. Each cell is enclosed in a
complex cell wall formed largely of a polysaccharide. Each bacterium is microscopic,
between 0.0005 and 0.005 mm (up to 0.0002 inch) in size. They reproduce rapidly by simple
division of cells to form large colonies or by sexual reproduction.
F. Karaca
FATIH UNIVERSTY, ENVIRONMENTAL ENGINEERING DEPARTMENT
ENVE 101-Introduction to Environmental Engineering
Bacteria are essential in the decomposition of organic matter, and in soil formation. They are
also necessary for the breakdown of sewage, and are used in the production of certain
fermented foods. They may also be used in the future to break up oil slicks in a technique
known as bioremediation. In biotechnological applications, bacteria are cultured on a large
scale to produce chemical products such as vitamins and enzymes in industrial quantities. A
minority of bacteria causes diseases, such as cholera, typhoid, and tuberculosis, often through
the manufacture of toxins. The control of such bacteria is important in food preservation, and
in many medical situations. Bacteria are also used as tools in genetic engineering.
Some information about bacteria:
Size:
Smallest living cells. Size ranges from 0.1 to 10 µm (1 µm= 10-6 m)
Most spherical cells have diameters from 0.5 µm to 2.0 µm.
Most rod shaped cells are 0.2 µm to 2.0 µm wide by 1 to 10 µm long
Major forms:
Cocci (spherical or oval)
diplococci- pairs
streptococci- chains
sarcinae-cubical
staphylococci- irregular clusters
Bacilli (rods)
coccobacilli-very short rods
fusiform-rods with tapered ends
vibrios-"comma-shaped," curved rods
Spiral shaped
spirilla-cells are rigid
spirochetes-cells are flexible and undulating
Pleomorphic-many different forms dependent upon growth conditions
Note: there are many thousands of species of bacteria. Shape does not
determine identification
Composition:
Greater than 90% composed of 5 macromolecules
Proteins ~55% of dry mass
RNA ~20%
DNA ~3%
carbohydrate ~5%
phospholipids ~6%
Protozoa
A group of unicellular or acellular, usually microscopic, organisms now classified in various
phyla of the kingdom Protoctista. They were formerly regarded either as a phylum of simple
animals or as members of the kingdom Protista. They are very widely distributed in marine,
freshwater, and moist terrestrial habitats; most protozoans are saprotrophs, but some are
parasites, including the agents causing malaria (Plasmodium) and sleeping sickness
(Trypanosoma), and a few contain chlorophyll and carry out photosynthesis, like plants.
Protozoan cells may be flexible or rigid, with an outer pellicle or protective test. In some
(such as Paramecium and Trypanosoma) cilia or flagella are present for locomotion; others
(such as Amoeba) have pseudopodia for movement and food capture. Contractile vacuoles
occur in freshwater protozoans. Reproduction is usually asexual, by binary fission, but some
protozoans undergo a form of sexual reproduction.
F. Karaca
FATIH UNIVERSTY, ENVIRONMENTAL ENGINEERING DEPARTMENT
ENVE 101-Introduction to Environmental Engineering
Unlike bacteria, protozoa ingest solid organics for food. They are voracious consumers of
organic materials.
Algae
Alga (plural: algae ) is common (non-taxonomic) name for a relatively simple type of plant
which is never differentiated into root, stem, and leaves; which contains chlorophyll a as the
primary photosynthetic pigment; which has no true vascular (water-conducting) system; and
in which there is no sterile layer of cells surrounding the reproductive organs. The algae range
in form from single cells (Protista) to plants many metres in length; algae can be found in
most habitats on Earth, although the majority occur in freshwater or marine environments.
Some species of algae can have negative effects on water quality because they produce oily
substances that cause taste and odor problems.
F. Karaca
FATIH UNIVERSTY, ENVIRONMENTAL ENGINEERING DEPARTMENT
ENVE 101-Introduction to Environmental Engineering
ATTACHMENT
Table 2.1- Solubility Products of Slightly Soluble Salts
Compound
AgBr
Ag2CO3
AgCl
Ag2CrO4
AgCN
AgI
Ag3PO4
Ag2SO4
Ag2S
AgCNS
Al(OH)3
BaCO3
BaCrO4
Ksp
5.35
8.45
1.76
1.12
5.97
1.18
8.88
1.20
6.69
1.03
2.
2.58
1.17
x
x
x
x
x
x
x
x
x
x
x
x
x
10-13
10-12
10-10
10-12
10-17
10-16
10-17
10-5
10-50
10-12
10-32*
10-9
10-10
Compound
BaF2
BaSO4
CaCO3
CaF2
CaSO4
CdS
Ca(OH)2
CuC2O4
CuS
Fe(OH)3
Hg2Br2
Hg2Cl2
HgS
Ksp
1.84
1.08
4.96
1.46
7.10
1.40
4.68
4.43
1.27
2.79
6.42
6.24
1.55
x
x
x
x
x
x
x
x
x
x
x
x
x
10-7
10-10
10-9
10-10
10-5
10-29
10-6
10-10
10-36
10-39
10-23
10-13
10-52
Compound
KClO4
MgCO3
MgF2
MgNH4PO4
Mg(OH)2
MnS
NiS
PbCl2
PbS
PbSO4
SnS
Zn(OH)2
ZnS
Ksp
1.05 x 10-2
6.82 x 10-6
7.42 x 10-11
2.
x 10-13*
9 x 10-12
4.65 x 10-14
1.07 x 10-21
1.78 x 10-5
9.05 x 10-29
1.82 x 10-8
3.25 x 10-28
4.13 x 10-17
2.93 x 10-25
F. Karaca