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Environmental Considerations of Engineering Design. Bo Hu John Nieber. Importance. Since late 1970, many developing countries including US have moved the environmental protection from a secondary to a primary issue for the manufacturing and transportation sectors!

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importance
Importance
  • Since late 1970, many developing countries including US have moved the environmental protection from a secondary to a primary issue for the manufacturing and transportation sectors!
  • More and more developing countries are having same regulations now!
wastes and pollution
Wastes and Pollution
  • Air pollution
  • Wastewater
  • Solid waste
  • Others
    • sound, radiation, odor, etc
environmental issues
Environmental Issues
  • Burning of fossil fuels for power generation and transportation
  • Handling of toxic wastes
  • Bioaccumulated chemicals
    • For examples: DDT, insect and pest control, banned by EPA in 1972
  • Toxic metals and minerals
    • Lead, banned in the paint in 1978, banned in the gasoline and replaced by MTBE
    • Mercury
    • Cadmium
    • Asbestos, ceiling materials
environmental factors in design
Environmental Factors in Design
  • Handling of toxic wastes
    • 97% of hazardous waste generated by the chemicals and nuclear industry is wastewater (1988 data).
    • In process design, it is essential that facilities be included to remove pollutants from waste-water streams.
  • Reaction pathways to reduce by-product toxicity
    • As the reaction operations are determined, the toxicity of all of the chemicals, especially those recovered as byproducts, needs to be evaluated.
    • Pathways involving large quantities of toxic chemicals should be replaced by alternatives, except under unusual circumstances.
  • Reducing and reusing wastes
    • Environmental concerns place even greater emphasis on recycling, not only for un-reacted chemicals, but for product and by-product chemicals, as well. (i.e., production of segregated wastes - e.g., production of composite materials and polymers).
environmental factors in design cont d
Environmental Factors in Design (Cont’d)
  • Avoiding non-routine events
    • Reduce the likelihood of accidents and spills through the reduction of transient phenomena, relying on operation at the nominal steady-state, with reliable controllers and fault-detection systems.
  • Material characterization
    • To maintain low concentrations of such chemicals below the limits of environmental regulations, it is important to use effective and rapid methods for measuring or deducing their concentrations from other measurements.
  • Design objectives, constraints and optimization
    • Environmental goals often not well defined because economic objective functions involve profitability measures, whereas the value of reduced pollution is often not easily quantified economically.
    • Solutions: mixed objective function (“price of reduced pollution”), or express environmental goal as “soft” or “hard” constraints.
    • Environmental regulations = constraints
environmental factors in design cont d1
Environmental Factors in Design (Cont’d)
  • Regulations
    • Some environmental regulations can be treated as constraints to be satisfied. The design team needs to check that these constraints are satisfied after the mathematical model is set up
    • Other regulations, however, are more difficult to quantify. These involves expectations of the public and the possible backlash should the plant be perceived as a source of pollution. Plant location is restricted.
  • Intangible costs
    • Cost of liability when a plant is found to be delinquent in satisfying regulations, including legal fees, public relations losses, delays incurred when environmental groups stage protests.
  • Properties of dilute streams
  • Properties of electrolytes
    • Ionic species such as acids, bases, and salts
    • Strong electrolytes dissociate into ionic species whose interactions with water and organic molecular are crucial to understanding the state of a mixture
slide9

Environmental Protection

U.S. Environmental Protection Agency (US EPA www.epa.gov)

Air, Water, Land

Air – Clean Air Act (1990 revision of 1970’s Act)

NAAQS – National Ambient Air Quality Standard

Criteria air pollutants are : Ozone, CO, Pb, NO2, SO2, Particulates (PM-10, PM-2.5)…

Air Toxics (PCB’s, PAH’s,…)

Toxic Release Inventory (TRI)

Water – Clean Water Act (1977 amendment to previous pollution Act)

Chemicals : Mercury, Urea, Phosphorus, Arsenic…

Land – Landfills, garbage dumps, radioactive waste, electronic products,

Mining (open cast, underground), urban expansion.

overview of the clean air act caa
Overview of the Clean Air Act (CAA)
  • The CWA and its amendments have been this country’s fundamental legislation controlling water pollution since 1972. Most of the CWA allegations against ranges involve the National Pollutant Discharge Elimination System (NPDES) program.
  • Under this program of the CWA it is illegal to “discharge” any “pollutant” from a “point source” into “waters of the United States” without a permit to do so. Under the CWA, waters of the United States encompass essentially all rivers, streams, lakes, ponds, drainage-ways, wetlands and similar features in the United States, including those entirely on private property.
  • It is important to note that the CWA does not prohibit the discharge of pollutants into waters of the U.S; it merely requires a permit to do so.
overview of the clean water act cwa
Overview of the Clean Water Act (CWA)
  • The CWA and its amendments have been this country’s fundamental legislation controlling water pollution since 1972. Most of the CWA allegations against ranges involve the National Pollutant Discharge Elimination System (NPDES) program.
  • Under this program of the CWA it is illegal to “discharge” any “pollutant” from a “point source” into “waters of the United States” without a permit to do so. It is important to note that the CWA does not prohibit the discharge of pollutants into waters of the U.S; it merely requires a permit to do so.
  • Under the CWA, waters of the United States encompass essentially all rivers, streams, lakes, ponds, drainage-ways, wetlands and similar features in the United States, including those entirely on private property.
solid waste disposal regulations
Solid waste disposal regulations
  • Solid Waste Disposal Act (1965)
    • To promote better management of solid wastes
    • To support resource recovery and disposal
  • U.S. Public Health Service
    • To promulgate and enforce regulations for solid waste collection, transportation, recycling, and disposal
  • Resource Recovery Act (1970)
    • Emphasis from solid waste disposal to recycling and energy recovery
solid waste disposal regulations1
Solid waste disposal regulations
  • Resource Conservation and Recovery Act (1976)
    • Significant requirements for the control of hazardous waste storage, treatment and disposal
  • Hazardous and Solid Waste Amendments (1984)
    • Revise of criteria for landfills
state and local laws and regulations
State and Local Laws and Regulations
  • federal environmental laws always permit the states to adopt standards more stringent than the federal standards.
typical treatments methods
Typical Treatments Methods
  • Municipal Wastewater Systems
  • Solid waste
physical characteristics of domestic wastewater

Color: gray (fresh), black (septic)

  • Odor: offensive
  • Temp: 10-20oC
  • Density: 1000 kg/m3 (almost same as that of water)
  • Solids: half of the weight is solids - 50% soluble, 50% insoluble (1/2 settled, and 1/2suspended)

Physical Characteristics of Domestic Wastewater

chemical characteristics of domestic wastewater

Chemical Characteristics of Domestic Wastewater

a measurement of total organic and inorganic N in wastewater

characteristics of industrial wastewater1

3

Priority Pollutants (table 1-6)

Characteristics of Industrial Wastewater

wastewater treatment standards

The Congress requires municipalities and industries to provide secondary treatment before discharging water into natural water bodies.

  • Secondary treatment is based on three characteristics:
  • BOD5
  • SS
  • pH

Wastewater Treatment Standards

npdes

National Pollutant Discharge Elimination System (NPDES):

  • Under NPDES program, any facility that discharge wastewater is required to obtain a NPDES permit
  • Before the permit is granted, administering agency will model the potential pollution (recall what you have learnt in “water quality management”)
  • The permit requires secondary treatment standards, or stricter.

NPDES

objectives of wastewater treatment
Objectives of Wastewater Treatment
  • Transform dissolved and particulate BOD into acceptable end products (i.e. CO2, H2O, stable products, and biomass)
  • Incorporate nonsettlable colloidal material into biological floc
  • Remove nutrients (N,P)
  • Remove trace organic constituents
slide25

Protect subsequent equipments in WWTP

Remove pollutants that settle or float

60% of SS removal; 35% of BOD5 removal

No removal of soluble BOD5

Remove soluble BOD5;

85% of SS and BOD5 removal

Remove soluble BOD5;

99% removal of SS, BOD5 , P, and bacteria

95% removal of N

Land treatment

slide26

Sludge (solid):

Need to be handled and disposed of

Land treatment

solid wastes
Solid Wastes
  • Non-liquid, non-soluble materials ranging from municipal garbage to industrial wastes that contain complex and sometimes hazardous substances. Solid wastes also include sewage sludge, agricultural refuse, demolition wastes, and mining residues.
solid waste sources
Solid waste sources
  • Four categories
    • Municipal, industrial, mineral extraction, and agricultural
  • Municipal waste sources
    • The materials discarded from residences, business and commercial waste
    • More recycling and energy recovery in the future will decrease the total amount of material that must be landfilled.
60 from residential

Ratio of MSW

60% from residential

40% from commercial

typical composition of residential msw by weight excluding recycled materials 1990
Typical composition of residential MSW (by weight) (excluding recycled materials, 1990)
slide32

Energy Recovery /Thermal Reduction

Solid waste management

Generation

Collection

Recycled

/Recovery

/Reuse

Transport

Landfill

landfill
Landfill
  • Defined as a land disposal site employing an engineered method of disposing of solid wastes on land in a manner that minimizes environmental hazards by spreading the solid wastes on the smallest practical volume, and applying and compacting cover materials at the end of each day.
homework iv
Homework IV
  • Think about possible pollutants from your process
  • Check with the local government and agencies about the requirements of the emission levels from your projected process
  • Find strategies to treat the wastes and decrease the emission level
  • Topic Discussion: There is a great push from our whole society to make regulations, restrictions and safety procedures in order to make our living environment cleaner and our working environment safer. However, many industries, especially heavy polluting industries, have been moved to places where there are less requirements to cut the cost. If you are the project manager, what is your choice between environment protection and profit? What can we do, in your opinion, to solve this problem?