---
watermark: ORIRO
disable-model-invocation: true
name: eng-environmental
provider: ORIRO.ai
copyright: Copyright (c) 2026 ORIRO.ai
description: >



  Environmental engineering — water treatment, air quality, waste management, contamination remediation, and environmental regulations.



  Sources: MIT OCW, ASME principles, OSHA, engineering textbook fundamentals.
  Consult a licensed professional engineer for safety-critical calculations.
---

# Environmental Engineering

## Water treatment (drinking water)

**Conventional treatment train:**

1. Coagulation/Flocculation: Add alum or ferric chloride. Destabilizes colloids. Gentle mixing forms flocs.
2. Sedimentation: Flocs settle. Gravity clarification.
3. Filtration: Sand/anthracite filters remove remaining particles. Target < 0.1 NTU turbidity.
4. Disinfection: Chlorine (most common), UV, ozone.
   **EPA MCLs (Maximum Contaminant Levels):** Legally enforceable limits. Turbidity < 1 NTU (treated), Nitrate < 10 mg/L, Lead < 15 µg/L action level.

## Wastewater treatment

**Primary:** Physical separation. Screening, grit removal, primary clarifiers. Removes ~60% TSS, 30% BOD.
**Secondary:** Biological treatment. Activated sludge (most common) uses microorganisms to consume organic matter. Removes >90% BOD and TSS.
**Tertiary/Advanced:** Nutrient removal (nitrogen, phosphorus), filtration, disinfection, reuse.
**BOD (Biochemical Oxygen Demand):** Measure of organic pollution. BOD₅ = oxygen consumed in 5 days at 20°C.

## Air quality

**Criteria pollutants (EPA NAAQS):** PM2.5, PM10, O₃, NO₂, SO₂, CO, Pb.
**PM2.5:** Particles < 2.5 µm. Most health-damaging. Annual standard: 12 µg/m³.
**Ground-level ozone:** Formed from NOx + VOCs + sunlight. NAAQS: 70 ppb 8-hour.
**Control technologies:**
Baghouse filters: 99%+ collection efficiency for particles.
Electrostatic precipitators: High efficiency for fine particles.
SCR (Selective Catalytic Reduction): NOx control for combustion sources.
Scrubbers: SO₂ removal using limestone slurry.

## Contaminated site assessment

**Phase I ESA:** Records review, site inspection, interviews. No sampling. Identifies RECs (Recognized Environmental Conditions).
**Phase II ESA:** Sampling and analysis. Confirms/characterizes contamination.
**Remediation technologies:**
Pump and treat: Extract contaminated groundwater, treat aboveground. Slow but established.
In-situ chemical oxidation (ISCO): Inject oxidants (permanganate, persulfate) to destroy contaminants.
Bioremediation: Enhance microbial degradation of contaminants.
SVE (Soil Vapor Extraction): Vacuum system extracts volatile compounds from vadose zone.

## Hazardous waste (RCRA)

Generator requirements: Proper labeling, storage time limits, manifests for transport.
Characteristic hazardous wastes: Ignitability (flash point < 60°C), corrosivity (pH < 2 or > 12.5), reactivity, toxicity (TCLP test).
Universal wastes: Batteries, fluorescent lamps, pesticides — simplified management.

Sources: EPA environmental regulations (epa.gov), Davis & Masten Introduction to Environmental Engineering (principles),
AWWA water treatment manuals, ASCE Environmental Engineering principles