Introduction to Environmental Engineering

• Engineering has traditionally been divided along disciplinary lines like electrical, chemical, civil, and mechanical.
• More specialized topics of popular interest have emerged over time, such as aerospace and computer engineering.
• Environmental engineering is a specialized area gaining in popularity that focuses on engineering solutions to environmental problems.
• The field of environmental studies was initially identified with civil engineering, focusing on water pollution and solid waste disposal.
• Modern environmental problems extend beyond civil engineering, requiring solutions from every engineering discipline.
• Engineers should consider that nearly everything they do can impact the environment, either positively or negatively.
• The "environment" is defined as the aggregate of surrounding things, conditions, or influences that affect the existence or development of something.
• The term "environment" refers to the physical environment that surrounds us, including the air, water, lands, and urban infrastructure.
• The state of the physical environment directly and indirectly affects the viability of all living things on the planet.
• Concern arises over environmental changes that may harm or affect welfare.
• Some changes may have short-term benefits but adverse long-term consequences like clear-cutting forests for agriculture that leads to soil erosion and productivity loss.
• In democratic societies, the political process determines whether environmental changes warrant policy measures based on risk assessment, cultural values, and economic trade-offs.
• The Clean Air Act forced automotive engineers to develop catalytic converters.
• Engineering has two impact categories including Land Use and Emissions.
• Engineers have an indirect role in Land Use such as advising on dam locations.
• Engineers have a direct responsibility for Emissions such as designing cleaner power plants.
• The engineering design of an automobile affects air pollutant emissions, fuel efficiency, and end-of-life waste generation.

Approaches to "Green" Engineering

• Environmental impacts can be addressed through three fundamental levers: materials selection, manufacturing processes, and energy use.

Materials Selection

• IBM reduced toxic metals in computer circuit boards when forced to handle recycling
• Key questions include: "Can we use less material?" and "Are there safer alternatives?".

Manufacturing Processes

• Every production stage (mining → refining → assembly) generates waste.
• The historical approach was end-of-pipe cleanup and the modern approach is pollution prevention.

Energy Use

• Any energy reduction = environmental benefit
• Switching energy sources requires life-cycle analysis.

Life Cycle Perspective stages

• Material extraction
• Processing
• Manufacturing
• Product use
• Waste management

Industrial Ecology

• Industrial ecology is the means by which humanity can deliberately and rationally approach and maintain a desirable carrying capacity.
• Four principles of industrial ecology include: circulate material flows, minimize material use, eliminate harmful substances, and reduce energy waste.
• The rate of creation of mass = 0.
• The applied form of the conservation of mass equation is (Total mass flow rate in) = (Total mass flow rate out) + (Rate of mass storage).
• In an example calculation: Input is 100 kg/day liquid waste. Outputs are 1 kg/day seepage + 2 kg/day evaporation. Storage is 97 kg/day accumulation.
• The first law equation is (Total energy in) = (Total energy out) + (Energy stored).
• In the power plant example: Fuel input is 100 million kW-hr. Electricity output is 30 million kW-hr. Waste heat is 70 million kW-hr (70% inefficiency).