Lecture 1
Introduction to Environmental Engineering DEFINITION
Environmental engineering is the application of science and engineering principl es to improve the environment (air, water, and/or land resources), to provide he althy water, air, and land for human habitation and for other organisms, and to remediate polluted sites.
water and air pollution control recycling
waste disposal
public health issues
environmental engineering law
studies on the environmental impact of proposed construction projects MIT s Department of Civil and Environmental Engineering
dedicated to balancing the built environment with the natural world. In our rese arch we seek to understand natural systems, to foster the intelligent use of res ources, and to design sustainable infrastructure systems.
Sustainable development
development that "meets the needs of the present without compromising the abilit y of future generations to meet their own needs."
Green buildings
Efficiently using energy, water, and other resources
Protecting occupant health and improving employee productivity Reducing waste, pollution and environmental degradation
Houses made of Earth bags A little history
Ancient Sewer from the Harappan civilization
Romans constructed aqueducts to prevent drought and to create a clean, healthful water supply for the metropolis of Rome
Public Health
John Snow and the Cholera Epidemic of London (1854) RACHEL CARSON S Hidden Spring
the birth of the modern environmental movement and the development of the modern field of "environmental engineering."
Civil Engineering
Environmental "civil" engineers focus on hydrology, water resources management a nd water treatment plant design.
Environmental "chemical" engineers, on the other hand, focus on environmental ch emistry, advanced air and water treatment technologies and separation processes. FIELDS OF PRACTICE / AREAS OF SPECIALIZATION
Sanitary Engineering (water supply & wastewater treatment) Air Pollution Control
Groundwater Flow & Contaminant Transport Solid and Hazardous Waste Management Environmental Impact Assessment
Lecture 2
MATERIALS AND ENERGY BALANCE
CE 131
Mass & Energy Balances
provide us with a tool for modeling the production, transport, and fate of pollutants in the environment. UNIFYING Theories
1. Conservation of Matter Matter can neither
be created nor destroyed .
Volumetric flow rate: Q= AV
MATERIALS/ MASS BALANCE
The mass that enters a system must, by conservation of mass, either leave the system or accumulate within the system . 2. Conservation of Energy
Energy cannot be created nor destroyed.
Mass and energy are two forms of the same thing. Energy is liberated matter, and matter is energy waiting to happen. -Bill Bryson
A Short History of Nearly Everything There is a huge amount- a
really huge amount- of energy bound up in every material thing.
An average-sized adult contains around 7x10^ 18 joules of
potential energy- enough to
explode with the force of 30 very large hydrogen bombs!
The total amount of energy and matter is constant.
3. Conservation of Matter and Energy MATERIALS BALANCE
For an ideal system,
Accumulation = Input Output
INPUTS Accumulation OUTPUTS CONTROL VOLUME
In the in the absence of a
nuclear reaction the number of atoms flowing in and out are the same, even in the presence of a chemical reaction. MATERIALS BALANCE To perform a balance the boundaries of the system must be well defined .
MATERIALS BALANCE
Materials balances can be simplified with the assumption of steady state, where the accumulation term is zero.
MATERIALS BALANCE
Example 3-1, page 89 (Davis)
Mr. and Mrs. Konzzumer have no children. In an
approximately 50 kg of consumer goods (food,
magazines, newspapers, appliances, furniture, etc.) . Of this amount, 50% is consumed as food. Half of the food is used for biological maintenance and ultimately released as CO2. The remainder is discharged to the sewer system.
The Konzzumers recycle approximately 25% of the solid waste that is generated. Approximately 1 kg accumulates in the house. Estimate the amount of solid waste they place at the curb each week.
Konzzumers residence Konzzumers residence 50 kg of consumer goods Konzzumers residence Konzzumers Residence 50% (food) 50 % for biological maintenance Waste CO2 Sewer system Other 50 % 25 % Solid waste recycled 1 kg accumulates in the house
? Estimate the amount of solid waste they place at the curb each week. The rest is
thrown out Solution:
Draw mass balance diagram. Consumer goods Food to people Solid Waste Accumulation Solution:
Write mass balance equation for the house. Consumer goods Food to people Solid Waste Accumulation INPUT = Accumulation + Output as Food + Output as solid waste Konzzumers residence Konzzumers Residence 50% (food) 50 % for biological maintenance
Waste CO2 Sewer system Other 50 % 25 % Solid waste recycled 1 kg accumulates in the house
? Estimate the amount of solid waste they place at the curb each week. The rest is
thrown out
Time as a factor
Modified mass balance equation: dt d out dt d in dt dM ? ( ) ? ( )
Rate of accumulation = rate of input rate of output Example 3-2, page 91 (Davis)
Truly Clearwater is filling her bathtub but she
forgot to put the plug in. If the volume of water for a bath is 0.350 m3 and the tap is flowing at 1.32
L/min and the drain is running at 0.32 L/min, how
long will it take to fill the tub to bath level? Assuming Truly shuts off the water when the tub is full and does not flood the house, how much water will be wasted? Assume density of water is 1,000 kg/m3.
More complex systems Black box
Study example 3-3
Mass of contaminant per unit time: (Concentration)(Flow rate) Time Mass ? s m3 m 3 mg s mg
MASS FLOW RATE
in in out out C Q C Q dt dM ? ? Where: C = concentration of contaminant Q= flow rate in in in in out out in in C Q C Q C Q C Q dM dt ? / ? Efficiency
x 100% mass in
mass in ?mass out ? ?
x 100%
concentration in
concentration in ? concentration out ? ?
If flow rate in and flow rate out are the same, Example 3-4, page 94 (Davis)
The air pollution control equipment on a municipal waste
incinerator includes a fabric filter particle collector (known as baghouse). The baghouse contains 424 cloth bags arranged
in parallel, that is, 1/424 of the flow goes through each bag.
Qin= Qout=47 m3/s Cin,particles= 15 g/m3
For normal operation, Cout=24 mg/m3 (regulatory limit)
During maintenance, one bag is inadvertently not replaced, so only 423 bags are in place.
Required:
1. Fraction of particulate matter removed and efficiency of the baghouse when all bags are in place and emissions
comply with the regulatory requirements. Baghouse
Mixing States
1. Completely mixed system
The output from the system is the same as the contents of the system.
2. Plug flow system Each drop of fluid along direction of flow is unique and has the same
concentration and
properties as when it had first entered the system. Steady state condition
The input rate and output rate are constant and equal. There is no accumulation of particles/materials.
Steady state does not imply equilibrium.
Accumulation = Input Output ± Transformation rate Accumulation Transformation INPUTS OUTPUTS Non-conservative pollutants r dt d out dt d in dt dM ? ( ) ? ( ) ? dt r ? ?kC n ?1 ? dC ? ? ? C t C k dt
C dC o 0 kt
oC ? C e?
In first-order reactions, the rate of loss of a substance is proportional to the amount of substance present at any time t.
Decay Rate for the mass balance equation is kCV. Where: C = pollutant concentration t = time k = reaction rate coefficient [T-1]
Mass balance equation for non-conservative pollutant: kCV dt d out dt d in dt dM ? ( ) ? ( ) ? Example 3-6:
Assuming no other water losses or gains and that the lagoon is completely mixed, find the steady-state concentration of the pollutant in the lagoon effluent. Note: The organic matter in the sewage decays in the lagoon.
Sewage Lagoon Cin= 180 mg/L Qin= 430 m3/day Ceff= ? Qeff= 430 m3/day Decay Surface Area of lagoon= 10 hectares Depth = 1.0 m k= 0.70 /day Sewage lagoon Lecture 3 Ecology
the study of how organisms interact with each other and their environments © J Beauchemin 2006
Introduction
Groups of animals live in specific habitats.
There are two factors included in every habitat:
Biotic factors
Living things, like ? Abiotic factors
Nonliving things, like ? Like a set of nesting dolls
We can think about the interactions and types of living things by organizing them into groups, smallest to largest.
A speciesincludes only one type of organism. Example: pigeon
A populationincludes all members of one speciesthat live in the same area. Example: all the pigeons in Manila
bigger and bigger groups!
A community includes all of the
different species that live in the same area.
Example: all the pigeons, ants, acacia trees, dogs, etc. that live in Manila
An ecosystem includes both the community and the abiotic factors.
Example: the Manila community plus the cars, buildings, rocks, air
The organisms in a habitat can be organized in the following way species
community population ecosystem Food webs
All organisms need FOOD to survive! Food webs show what eats what. Eat or be eaten
Here are some important terms that will help you describe interactions in a food web.
1. Producer (autotroph) can make its own food
forms the base of the food web Mmmmm delicious.
2. Consumer (heterotroph) cannot make its own food
There are several words that describe consumers Prey: the hunted
Predator: the hunter Herbivore: eats plants Carnivore: eats animals
Omnivore: eats both plants and animals Hey, you gonna eat that?
3. Decomposer
Breaks down dead organisms
Examples: bacteria, maggots, fungi, worms
Complete the circle of life by returning nutrients to the soil
Trophic LevelsThe trophiclevelof an organism is its position in a food chain. Food Chain
-the feeding of one organism upon another in a sequence of food transfers.
-chain of transfer of energy (which typically comes from the sun) from one organ ism to another
Food Web
In an ecosystem there are many different food chains and many of these are cross -linked to form a food web.
Ecological Pyramids
Biomass Pyramidthis pyramid indicates the total mass of the organisms in each tr ophiclevel.
Energy pyramid
indicates the total amount of energy present in each trophiclevel. It also shows the loss of energy from one trophiclevel to the next.
Pyramid of Numbers
A pyramid of numbers is a graphical representation of the numbers of individuals in each population in a food chain.
Bioaccumulation
which the substance is lost. Bioconcentration
defined as occurring when uptake from the water/air is greater than excretion. Bioconcentration differs from bioaccumulation because it refers only to the uptak e of substances into the organism from water alone.
Biomagnification
is the process that results in the accumulation of a chemical in an organism at h igher levels than are found in its own food.
Thus bioconcentration and bioaccumulation occur within an organism, and biomagni fication occurs across trophic (food chain) levels.
The Carbon CycleThe movement of carbon, in its many forms, between the atmospher e, oceans, biosphere, and geosphere.
Geological and Biological Carbon Cycle
Human alteration of the Carbon Cycle
Human activities such as the burning of fossil fuels and deforestation have acce lerated.
Some facts about Deforestation
Deforestation is thought to be releasing about 2.2 gigatons of carbon every year into the atmosphere.
Deforestation occurs at a rate of 150,000 square km per year worldwide (every 2. 5 years, an area equivalent to the state of California disappears).
Tropical forests once occupied 16 million square kilometers of the earth's surfa ce, but now cover only 9 million.
It is estimated that Latin America and Asia have already lost 40% of their origi nal forest; Africa a little more than half.
In many countries the rate of deforestation is accelerating. For example, most o f the forested areas of Bangladesh, India, the Philippines, Sri Lanka and parts of Brazil's rain forest could be gone by the end of the century.
Only in the Congo Basin and some of the more isolated areas of the Amazon Basin does the forest remain largely intact.
The Keeling curve, a long-term record of atmospheric CO2concentration measured at t he Mauna Loa Observatory. Carbon concentrations are higher than they have been i
n 400,000 years.
Global mean temperature will increase between 1.4 and 5.8 degrees C over the nex t century as a result of increases in atmospheric CO2and other greenhouse gases. EFFECTS
significant rise in average sea-level (0.09-0.88 meters), exposing low-lying coas tal cities or cities located by tidal rivers such as New Orleans, Portland, Wash ington, and Philadelphia to increasingly frequent and severe floods.
Melting of the polar ice caps
impact on patterns of plant growth worldwide.
Because some species of plants respond more favorably to increases in CO2than oth ers, scientists believe we may see pronounced shifts in plant species as a resul t of increasing atmospheric CO2concentrations
The process of adding nutrients initially lacking in the ocean to enhance phytop lankton bloom.
Phytoplankton bloom in the Atlantic
Ocean fertilizationDuring the 198: s fertilization of the ocean was proposed to ex tract carbon dioxide from the atmosphere
1. Add Nutrients to the Ocean 2. Phytoplankton bloom
3. Carbon Drawdown
4. Reduce Global Warming
