ENVIRONMENTAL ENGINEERING
441Lecture Time:
Class 1: 11:15 to 12:45
Monday & Wednesday
Philadelphia UniversityFaculty of Engineering
Department of Civil EngineeringFirst Semester, 2013/2014
INTERNATIONAL SYSTEM OF UNITS
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 mol
luminous intensity
candela cd
SI DERIVED UNITSType Name Symbol
acceleration meter/square second
m/s2
angle radian rad
area square meter m2
capacitance farad F
density kilogram/cubic meter
kg/m3
dynamic viscosity pascal second Pa-s
electric charge coulomb C
electric conductance
siemens S
electric resistance ohm Ω
energy joule J
force newton N
frequency hertz Hz
Type Name Symbol
inductance henry H
mass flow rate kilogram/second kg/s
mole flow rate mole/second mol/s
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
volume cubic meter m3
volume flow rate cubic meter/second
m3/s
amount-of-substance concentration
mole/cubic meter
mol/m3
SI PREFIXES Factor Prefix Symbol 1024 1E24 yotta Y 1021 1E21 zetta Z 1018 1E18 exa E 1015 1E15 peta P 1012 1E12 tera T 109 1E9 giga G 106 1E6 mega M 103 1E3 kilo k 102 1E2 hecto h 101 1E1 deca da 101 1E1 deka da 10-1 1E-1 deci d 10-2 1E-2 centi c 10-3 1E-3 milli m 10-6 1E-6 micro µ 10-9 1E-9 nano n 10-12 1E-12 pico p 10-15 1E-15 femto f 10-18 1E-18 atto a 10-21 1E-21 zepto z 10-24 1E-24 yocto 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 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 symbolConversion
factor (mutiply USCS unit with
factor )Square foot Square meter m2 0.0929Cubic foot Cubic meter m3 0.2831
Pound per square inch Kilopascal kPa 6.894
Pound force Newton N 4.448Foot 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 FOLLOWINGHTTP://WWW.ONLINECONVERSION.COM/
EXAMPLE #1: CONCENTRATIONS AND CONVERSIONSSome 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 BALANCESMB 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 of300,000 cfs. GE discharges to the Hudson with
a flow rate of 10 cfs. The concentrationof 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
EXAMPLE #2 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 WORK1. 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.
2. 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
influent Effluent
QinCAin
Q outC Aout
V (m3)
Reactor
Input – output+ generation= accumulation
GENERAL MATERIAL BALANCE EQUATION FOR FIRST ORDER REACTION RATES:
VdC/dt =ΣCinQin − ΣCoutQout ± kCVC = concentration in the control volume (river/stream/reactor) [=] mg/LV = volume of control volume [=] L, m3, ft3
Qin = flowrate of inlet streams [=]m3/s, L/s, cfs, MGDQout = summation of all outlet streams [=]m3/s, L/s, cfs, MGDCin = concentration in each inlet stream [= ] mg/LCout = concentration in each inlet stream [= ] mg/Lk = 1st order reaction rate constant (will be given) [=] 1/st = time [=] sec, mi
influent Effluent
QinCAin
Q outC Aout
V (m3)
Reactor