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FE Environmental study materials
FE Environmental study resources

FE Environmental cheat sheet

FE Environmental · Keep the key ideas within reach.

Quick reference

Environmental Engineering Fundamentals

  • Mass balance: accumulation = inputs − outputs ± reactions; at steady state, inputs + generation = outputs + consumption.

  • Ideal gas law: PV = nRT; at standard conditions (0°C, 1 atm), 1 mol occupies 22.414 L; at 25°C, 24.465 L.

  • Concentration units: 1 mg/L = 1 ppm (aqueous, density ≈ 1 kg/L); 1 µg/L = 1 ppb; in air, ppmv = (L contaminant/10^6 L air).

  • Henry's law: p = H·x or C_air = H'·C_water; H increases with temperature, decreasing solubility of gases.

  • Reaction kinetics: zero-order: C = C0 − kt; first-order: C = C0·e^(−kt); half-life t½ = ln2/k ≈ 0.693/k.

  • Stoichiometry: theoretical oxygen demand (ThOD) for C₆H₁₂O₆: 6 mol O₂ per mol glucose; use balanced equation.

  • Darcy's law: Q = K·i·A, where i = hydraulic gradient (Δh/ΔL), K = hydraulic conductivity, A = cross-sectional area.

  • Reynolds number: Re = ρVD/μ; laminar flow in pipes Re < 2,100; transitional 2,100–4,000; turbulent > 4,000.