Philadelphia University
Faculty of Engineering
Department of Civil Engineering
First Semester, 2013/2014
ENVIRONMENTAL
ENGINEERING
441
Lecture Time:
Class 1:
11:15 to 12:45
Monday & Wednesday
INTERNATIONAL SYSTEM OF UNITS
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The International System of Units (abbreviated SI) is the modern
form of the metric system. It is the world's most widely used system of
units, both in everyday commerce and in science.
The older metric system included several groupings of units. The SI
was developed in 1960 from the metre-kilogram-second (mks) system,
rather than the centimetre-gram-second (cgs) system which, in turn,
had many variants.
The SI introduced several newly named units. The SI is not static; it
is a living set of standards where units are created and definitions are
modified with international agreement as measurement technology
progresses.
With few exceptions, the system is used in every country in the world,
and many countries do not maintain official definitions of other units.
In the United States, industrial use of SI is increasing, but popular
use is still limited. In the United Kingdom, conversion to metric units
is official policy but not yet complete. Those countries that still
recognize non-SI units (e.g. the U.S. and UK) have redefined their
traditional non-SI units in terms of SI units.
SI BASE UNITS
Type
Name
Symbol
length
metre
m
mass
kilogram
kg
time
second
s
electric current
ampere
A
temperature
kelvin
K
amount of
substance
mole
luminous intensity candela
mol
cd
SI DERIVED UNITS
Type
Name
Symbol
inductance
henry
H
mass flow rate
kilogram/second
kg/s
rad
mole flow rate
mole/second
mol/s
m2
power
watt
W
pressure
pascal
Pa
speed
meter/second
m/s
surface tension
newton/meter
N/m
torque
newton meter
N-m
voltage
volt
V
Type
Name
Symbol
acceleration
meter/square
second
m/s2
angle
radian
area
square meter
capacitance
farad
density
kilogram/cubic
meter
F
kg/m3
dynamic viscosity
pascal second
Pa-s
electric charge
coulomb
C
electric
conductance
siemens
S
volume
cubic meter
m3
electric resistance
ohm
Ω
volume flow rate
cubic
meter/second
m3/s
energy
joule
J
force
newton
N
mole/cubic meter
frequency
hertz
Hz
amount-ofsubstance
concentration
mol/m3
SI PREFIXES
Factor
1024
1021
1018
1015
1012
109
106
103
102
101
101
10-1
10-2
10-3
10-6
10-9
10-12
10-15
10-18
10-21
10-24
1E24
1E21
1E18
1E15
1E12
1E9
1E6
1E3
1E2
1E1
1E1
1E-1
1E-2
1E-3
1E-6
1E-9
1E-12
1E-15
1E-18
1E-21
1E-24
Prefix
yotta
zetta
exa
peta
tera
giga
mega
kilo
hecto
deca
deka
deci
centi
milli
micro
nano
pico
femto
atto
zepto
yocto
Symbol
Y
Z
E
P
T
G
M
k
h
da
da
d
c
m
µ
n
p
f
a
z
y
USCS - UNITED STATES CUSTOMARY SYSTEM UNITS
USCS - United States Customary System Units: are
the measuring units used in the U.S. consisting of
the
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Mile (eq 1609.344 m)
Foot (equal 0.3048 m)
Inch (eq 0.0254 m)
Gallon ( US eq 3.785 L) (UK eq 4.546 L)
second
Pound (eq 0.45359 Kg)
Commonly used USCS and SI-units
USCS unit
SI unit
SI symbol
Conversion factor
(mutiply USCS
unit with factor )
Square foot
Cubic foot
Pound per square
inch
Pound force
Square meter
Cubic meter
m2
m3
0.0929
0.2831
Kilopascal
kPa
6.894
Newton
N
4.448
Foot pound torque
Newton meter
N·m
1.356
Kip foot
Kilonewton meter
kN·m
1.356
Gallon per minute
Liter per second
L/s
0.06309
Kip per square inch
Megapascal
MPa
6.89
FOR ONLINE CONVERSION YOU CAN USE THE FOLLOWING
HTTP://WWW.ONLINECONVERSION.COM/
EXAMPLE #1: CONCENTRATIONS AND
CONVERSIONS
Some employees at GE wash the PCB tainted floor
with organic solvent (TCE) and the discharge
enters a holding tank that is 25 m x 25 m x 5 ft and
is full with water. The volume of solvent is 3 L and
the concentration of PCBs in the solvent is 10 ppm.
What is the final concentration of PCB in mg/l in the
holding tank?
MATERIAL BALANCES
MB is a key tools in achieving a quantitative
understanding of the behavior of environmental
systems.
Mass Balances provide us with a tool for modeling
the production, transport, and fate of pollutants
in the environment.
MATERIAL BALANCES / MASS BALNCE
Conservation of mass
Mass is neither created nor destroyed”
Mass that comes in either stays, reacts or goes out.
“the sum of weights (masses) of substances
entering into a reaction is equal to the sum of
weights (masses) of the products of the reaction
Feed In
Products out
Inputs - Output = Accumulation
STEADY STATE FLOW CONSERVATIVE
SYSTEM:
Steady State Flow, conservative system:
Σ CinQin = ΣCoutQout
Assumption #1: Steady‐state: no change in conc.
throughout control volume
Assumption #2: Conservative system: No reaction
EXAMPLE #1
The Hudson river flows with a flow rate of
300,000 cfs. GE discharges to the Hudson with a
flow rate of 10 cfs. The concentration
of PCBs in the discharge is 5 g/L. What is the final
concentration in the river?
downstream from the discharge? Assume perfect
mixing.
Also assume concentration of PCBs upstream of the
discharge is 0 ppm.
STRATEGY OF SOLVING MB
Sketch a flow chart or figure defining the boundary of
the process
 Label the flow of each stream & their composition with
symbols
 Show all known flows and compositions on the figure.
Calculate additional compositions from the data where
possible
 Select the basis for calculations e.g. 1h, 1 day, 1 kg, etc
 Write the MBs which includes the total balance and
component balances. There must be x independent
equations if there are x unknowns
 Solve the equations and check the solutions
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EXAMPLE #2
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A wastewater treatment plant with an output of
38400m3/day discharges the liquid effluent with a
BOD of 20mg/L into a river. If the BOD of the
river upstream of the discharge point is 0.2mg/l,
at a minimum flow of 20m3/s, compare the BOD
of the river downstream of the discharge,
assuming complete mixing.
Answer = 0.63mg/L
EXAMPLE #3
A slurry containing 20 percent by weight of
limestone (CaCO3) is processes to separate pure
dry limestone from water. If feed rate is
2000kg/h, how much CaCO3 is produced per
hour?
HOME WORK
1.
2.
Each day 3780 m3 of wastewater is treated at a
municipal wastewater treatment plant. The
influent contains 220 mg/L of suspended solids.
The clarified water has a suspended solids
concentration of 5mg/L. Determine the mass of
sludge produced daily from the clarifier and
write down the mass balance of the clarifier.
As a fuel source 20kg of ethylene (C2H4) is
burned with 400 kg of air. Determine the
composition of the resulting mixture. What is
the percentage of excess air, assuming complete
conversation?
ANALYSIS PERFORMANCE OF REACTOR TYPE
Reactor
influent
Qin
CAin
Effluent
V (m3)
Q out
C Aout
Input – output+ generation= accumulation
GENERAL MATERIAL BALANCE EQUATION
FOR FIRST ORDER REACTION RATES:
Reactor
influent
Qin
CAin
Effluent
V (m3)
Q out
C Aout
VdC/dt =ΣCinQin − ΣCoutQout ± kCV
C = concentration in the control volume (river/stream/reactor) [=]
mg/L
V = volume of control volume [=] L, m3, ft3
Qin = flowrate of inlet streams [=]m3/s, L/s, cfs, MGD
Qout = summation of all outlet streams [=]m3/s, L/s, cfs, MGD
Cin = concentration in each inlet stream [= ] mg/L
Cout = concentration in each inlet stream [= ] mg/L
k = 1st order reaction rate constant (will be given) [=] 1/s
t = time [=] sec, mi