Water and wastewater
- Detention time θ = V/Q; overflow rate = Q/A
- BOD_t = L₀(1 − e^(−kt))
- Mass loading (lb/day) = flow (MGD) × concentration (mg/L) × 8.34
Hydrology and groundwater
- Rational method Q = CiA
- Darcy's law Q = KiA; seepage velocity = Ki/n_e
- Continuity Q = AV
Chemistry and kinetics
- First order: C = C₀e^(−kt); half-life = ln 2/k
- pH = −log[H⁺]; pH + pOH = 14 at 25 °C
- Ideal gas: PV = nRT; ppm by volume to mg/m³ uses MW/24.45 at 25 °C
Air, waste and risk
- Removal efficiency = (in − out)/in
- Cancer risk = chronic daily intake × slope factor
- Hazard quotient = intake ÷ reference dose
Test yourself on FE
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