Environmental Science and Technology
Environmental science and technology
This domain tests the science behind contamination and the technologies used to monitor, treat, and remediate it. Questions often ask you to select a technology based on contaminant properties, geology, and cost.
Core concepts
- Fate and transport: advection moves contaminants with groundwater; dispersion spreads them; sorption retards metals and hydrophobic organics; biodegradation can attenuate petroleum hydrocarbons.
- Air control: cyclones remove coarse particulates; baghouses and ESPs capture fine particles; scrubbers remove acid gases; thermal oxidizers destroy VOCs.
- Water treatment: coagulation/flocculation, sedimentation, filtration, and disinfection for drinking water; activated sludge for BOD; carbon adsorption for organics.
- Remediation: pump-and-treat for dissolved plumes; SVE for volatile organics in the vadose zone; bioremediation for biodegradable organics; thermal desorption for soils.
- Sampling: chain of custody, blanks, duplicates, and method detection limits determine defensibility.
Worked example
Groundwater contains 50 mg/L trichloroethene at 100 m³/day. Mass flux = 50 mg/L × 100,000 L/day = 5,000,000 mg/day = 5 kg/day. If treatment lowers the effluent to 5 mg/L, removed mass = (50−5) mg/L × 100,000 L/day = 4.5 kg/day. A 90% removal efficiency is not the same as meeting a 5 µg/L standard; check the standard separately.
Traps
Confusing removal efficiency with compliance; using SVE below the water table; ignoring daughter products such as vinyl chloride; and treating a detection limit as zero.