Environmental Engineering, Emissions and Effluent Control
Environmental Engineering, Emissions and Effluent Control tests the engineering that keeps air, water and soil releases inside Egyptian limits: dispersion estimation, control equipment selection, wastewater treatment and the EIA process.
Air
- Gaussian plume: C = Q/(π u σy σz) · exp(−H²/(2σz²)) · exp(−y²/(2σy²)), with stability class from Pasquill–Gifford and effective stack height including plume rise.
- Control: cyclones and ESPs for coarse particulates, baghouses for fine dust, wet scrubbers for SO2 and acid gases, SCR/SNCR for NOx, flares and vapour recovery for VOCs; each has a characteristic efficiency and generates its own waste stream.
- Egyptian ambient standards sit in the Executive Regulations of Law 4/1994 as amended by Law 105/2015; the EIA screening category (A, B or C) fixes the depth of study.
Water
- Primary (settling), secondary (activated sludge, trickling filters), tertiary (filtration, disinfection, nutrient removal).
- Design parameters: F/M ratio, solids retention time, MLSS, and BOD/COD removal; the COD/BOD ratio indicates biodegradability.
- Egyptian discharge controls: Law 4/1994 and its Executive Regulations set limits for discharge to sewer, drains and receiving water; Law 48/1982 separately protects the Nile and its branches, so a Nile discharge must satisfy both.
Worked example - plume concentration
A stack emits 50 g/s of SO2; wind 3 m/s at 10 m; at 1 km, σy = 60 m and σz = 30 m; stack height 50 m. C = 50/(π × 3 × 60 × 30) × exp(−2500/(2 × 900)) = 2.95 × 10⁻³ × 0.249 = 7.3 × 10⁻⁴ g/m³, about 730 µg/m³. Compare this with the ambient limit; if it exceeds it, the options are a taller stack, a scrubber, or a lower emission rate.
Traps
- Using the centreline concentration for a receptor that is off-axis.
- Ignoring plume rise when computing effective stack height.
- Treating BOD removal as a proxy for toxicity removal.
- Missing the dual Nile requirements of Law 4/1994 and Law 48/1982.