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DESIGN PRINCIPLES IN ENVIRONMENTAL ENGINEERING Instructor: Jayant M Modak Course: UES 302
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DESIGN PRINCIPLES IN ENVIRONMENTAL ENGINEERING
Instructor: Jayant M Modak Course: UES 302
Textbook
Principles of Environmental Engineering & Science
Davis, M.L and Masten S. J., McGraw-Hill(India) 2e, 2013.
INFORMATION
Schedule
• M-W 10-11 AM
Office: Rm 14
Phone: 3108
Email: [email protected]
EVOLUTION OF CHEMICAL ENGINEERING: 1860’S -1930’S
Industry/Technology driven Coal derived chemicals Bulk inorganic chemicals – caustic soda, soda ash Oils, fats, waxes Soaps and detergents Ammonia and its derivates
EVOLUTION OF CHEMICAL ENGINEERING: 1940’S-1960’S
Unit Operation !
Distillation Drying Mixing
Crushing/Grinding Heat Exchange
Combustion Oxidation Hydrolysis
Coal
Petroleum
Petrochemicals
FermentationOils, fats
Inorganics
Ammonia
Polymers
electronic
EVOLUTION OF CHEMICAL ENGINEERING: 1960’S -1990’S
Chemical Engineering Science
!Thermodynamics
Transport processes Reaction Engineering
Mathematical Modeling Process Control
Separations
Distillation
Drying
CrushingHeat exchange
Oxidation
Combustion
Hydrolysis
Electronics Environment Biotech
Industry
CHEMICAL ENGINEERING
Different from other disciplines
Does not have a product of its own
It is a service discipline
Other disciplines are composite in nature
!
Scope of Chemical Engineering
Based on tools, techniques, rather than products
Learn new techniques and enter new disciplines
!
All pervading, ever-expanding?
EVOLUTION OF ENVIRONMENTAL ENGINEERING
Water supply, sanitation and treatment
Early civilisation
2000 BC – Ousruta Samghita and Sussruta samhita
Air pollution control
19th century – fabric filters, cyclone collectors, scrubbers, electrostatic precipitators
Solid waste management
20th century – incinerators, landfills
Hazardous waste management
Late 20th century – remediations
!
Closely associated with Civil Engineering (19th century) but started emerging as distinct discipline in 1970’s and 80’s
ENVIRONMENTAL ENGINEERING
Application of basic fundamentals of mathematics, physics, chemistry, and biology to the protection of human health and the environment.
Fundamentals of Environmental Engineering, Mihelcic
!
Discipline is largely defined by problems rather than by technical/scientific methods.
!
Typical problems:
!
Remediation of a contaminated site (= fixing the past)
Treatment of a dirty effluent (= dealing with the present)
Pollution avoidance (= planning for future).
ENVIRONMENTAL ENGINEERING
!
Breadth, interdisciplinary (systems thinking, various engineering disciplines, even non-engineering disciplines).
!
Challenges: Avoidance of moving one waste from one phase to another (ex. water to solid waste); Prevention is harder than treatment; Environmental benefit versus economic burden (trade-off).
!
Role of the public sector:
In other areas of engineering, a need creates a market and the market drives technology development
In environmental engineering, it starts with a problem, which drives regulations, regulations create the market, and the market drives the technology.
ENGINEERING ANALYSIS OF ENVIRONMENTAL SYSTEMS
Objective
to predict how they will behave
to explain why they behaved as they did.
Key steps
Translate the physical system into a mathematical representation.
Solve the mathematical problem to obtain the result.
Interpret the significance of the result for the physical system.
ENGINEERING ANALYSIS OF ENVIRONMENTAL SYSTEMS
Translate the physical system into a mathematical representation.
Identify and specify symbols to represent the unknowns.
Identify and quantify the known parameters and variables in the system.
Identify and write relationships based on physical, chemical, or biological principles that link the unknowns to the knowns. For the problem to be fully specified, there must be one relationship for each unknown, and these relation- ships must be independent of one another
SITUATION 1: MUNICIPAL WASTE WATER TREATMENT
http://www.saskatoon.ca/DEPARTMENTS/Utility Services/Water and WastewaterTreatment/Wastewater Treatment Plant/Pages/default.aspx
SITUATION 1: MUNICIPAL WASTE WATER TREATMENT
http://en.wikipedia.org/wiki/Sewage_treatment
SITUATION 1: MUNICIPAL WASTE WATER TREATMENT
How do I design, construct and operate a treatment plant to treat specific water, given that I must treat certain volume of wastewater daily, and influent water has certain characteristics?
!
How large a reactor must I construct, can I speed up a chemical or biological reaction?
!
If I have several types of reactors which one do I choose?
!
How much of a particular waste can I discharge?
SITUATION 2: ACID RAIN
http://science.howstuffworks.com/nature/climate-weather/atmospheric/acid-rain.htm
SITUATION 2: ACID RAIN
How do I design, construct and operate a physical, chemical, or biological treatment method to scrub SO2 and NOx from stack gas?
!
If I scrub acid-rain precursors, do I create a water-pollution which I will have to treat as well?
!
What is the atmospheric chemistry of acid-rain production, and how fast do the reactions take place?
!
How are air emissions mixed and transported downwind?
SITUATION 3: HAZARDOUS WASTE
PESTICIDES
Aldrin, Dieldrin, Chlordane, DDT, Endrin, Heptachlor, Mirex, Toxaphene
INDUSTRIAL CHEMICALS
PCBs, HCB
UNINTENDED BYPRODUCTS
Dibenzodioxins, Dibenzofurans
Prod
uctio
n (b
illio
n K
g/ye
ar)
0
300
600
900
1200
Year
1930 1950 1970 1985 2005 2015
Hazardous material corrosivity (i.e., possesses very high or very low pH) ignitability reactivity (e.g., may cause an explosion) toxicity (i.e., causes harm to biological systems)
DESIGN OF WASTEWATER TREATMENT REACTOR
Objectives
!
Technological
Maximum possible treatment in minimum time
Desired quantity in minimum time
Maximum possible treatment in desired time
!
Economic
Minimize cost
DESIGN OF WASTEWATER TREATMENT REACTOR
Constraints
Market
Influent water availability – quality and quantity
Daily and seasonal variations in influent water
Society/Legislative
Safety
Effluent discharge norms
Political pressures
Inadequate space
Technological
Thermodynamics
Stoichiometry
Kinetics
OUTLINE OF COURSE
Fundamentals
Mass and Energy Balances
Transformation processes: Chemical and Biological
Transport processes
!
Applications
Water
Air
Hazardous waste
SELECTION OF TOPICS
Impossible to include all the elements of environmental engineering in a single course.
!
I am a Chemical Engineer and it is possible that courses elsewhere might have different emphasis
!
Provide a balanced view of the many elements comprising environmental engineering
!
Emphasise topics that can be approached analytically rather than descriptively.
