Environmental Engineering – Comprehensive Exam Notes

Air Pollution Control Technologies

Overall Control Hierarchy

Elimination / Reduction of pollutant or source (e.g., phase‐out of a toxic chemical)
Substitution (public transport, cycling, walking instead of private cars)
Engineering Controls (installing treatment technologies)
Administrative Controls (laws, zoning, penalties)
Personal Protective Equipment (PPE) – e.g., face masks for citizens

Inertial Separators / Cyclones

Purpose: removal of large dust particles in factories, woodworking shops, grain mills
Physical principles: centrifugal, gravitational, inertial forces
Basic sequence
1. Dirty air enters a curved/spinning chamber
2. Rapid change of direction generates centrifugal force
3. Heavier particles can’t follow the airstream – crash into wall / fall out
4. Dust collected in bin or hopper
5. Cleaned air exits
ReCyclone® MH System – combines cyclone + recirculator to boost removal efficiency

Fabric Filters / Bag-houses

Gas stream forced through fabric bags ("giant socks") that trap fine particulate
Good for very fine dust (cement plants, power stations)
Operating cycle
1. Dirty gas enters housing
2. Particles deposit on outside of bags, cake builds up
3. Periodic shake / pulse-jet knocks cake into hopper
4. Continuous clean gas discharge
Efficiency routinely >99\% for particles <1\,\mu m

Wet Scrubbers

Polluted gas contacted with scrubbing liquid (usually water)
Removes: soluble gases ((\text{SO}_{2}), (\text{HCl})), odors, fine PM
Steps
1. Inlet gas sprayed or bubbled through liquid
2. Pollutants absorbed or adhere to droplets
3. Dirty liquid collected at bottom, routed to wastewater treatment
4. Clean gas exits top
Variants: spray towers, packed towers, venturi scrubbers

Electrostatic Precipitators (ESP)

Use electrostatic forces on charged particles
Configuration: alternating discharge wires & grounded plates
Five-step process
1. Gas enters; corona discharge ionises gas
2. Particles acquire negative charge
3. Charged particles migrate to positive plates
4. Dust layer periodically rapped/washed off
5. Efficiency very high for sub-micron particles; can exceed $99.9\%$

Dust Unit Collectors (Point Source Vacuums)

Small, self-contained collectors serving one machine (grinder, sander)
Combine cyclone, cartridge filters or bags
Capture dust at source → prevents spread in shop

Comparative Summary

Inertial Separator – large particles, low cost, low pressure drop
Fabric Filter – fine dust, high >99\% removal, higher ΔP
Wet Scrubber – gases + PM, handles high temps, creates liquid waste
ESP – very small PM, high efficiency, high capital
Unit Collector – localized control for small jobs

Water & Wastewater Engineering

Source Protection / Prevention

Protect watersheds and wellheads from pollutants
Reforestation limits erosion → reduces turbidity
Sanitation infrastructure prevents microbial contamination

Wastewater Typology

Gray – kitchen, bath, laundry
Black – feces + urine
Yellow – urine only
Brown – feces only

Typical Odor Indicators

Amines – fishy (malansa)
Ammonia – "mapanghi"
Diamines – decayed fish/flesh
$\text{H}_{2}\text{S}$ – rotten eggs
Mercaptans – decayed cabbage / skunk
Skatole – fecal

Unsafe Drinking-Water Contaminants

Physical: sediments / turbidity
Chemical: nutrients, heavy metals, minerals
Microbiological: bacteria, viruses, protozoa
→ Necessitates treatment

Water Supply Flow

Source → Water Treatment Plant (e.g., Maynilad) → Distribution to consumers

Conventional Potable Treatment

Coagulation (add alum, $\text{Al}<em>{2}(\text{SO}</em>{4})_{3}$ ) & Flocculation (gentle mixing → flocs)
Sedimentation (flocs settle by gravity)
Filtration (sand/gravel/anthracite removes turbidity)
Disinfection (chlorine, ozone, UV, or household boiling)

Wastewater Treatment Train

Preliminary – screens & grit chambers remove large debris, sand, gravel
Primary – sedimentation of suspended solids → primary sludge; skim off oil/grease
Secondary – biological oxidation (activated-sludge aeration) then secondary clarifier; microbes convert BOD → $\text{CO}<em>{2}+\text{H}</em>{2}\text{O}$
Tertiary (optional) – nutrient removal (N, P), advanced filtration, activated carbon, membrane processes
Disinfection – chlorine/UV/ozone before discharge or reuse
Sludge Treatment – thickening → anaerobic digestion → dewatering; end uses: fertilizer, landfill, biogas-to-energy

Noise Pollution & Soil Pollution

WHO Community Noise Guidelines (1999) – Key Values

Outdoor living areas
- Serious annoyance: $55\,\text{dB}$ (LAeq,16 h)
- Moderate annoyance: $50\,\text{dB}$ (LAeq,16 h)
Indoor dwellings: speech intelligibility target $35\,\text{dB}$ (LAeq,16 h)
Bedrooms: sleep disturbance thresholds indoor $30\,\text{dB}$ (night); outdoor $45\,\text{dB}$
Schools: classrooms $35\,\text{dB}$
Industrial hearing impairment risk: $70\,\text{dB}$ for 24 h or $110\,\text{dB}$ LAmax

Philippine PD 856 Provisions (excerpts)

Establishments exceeding maximum allowable noise must locate in proper zones or supply PPE
Classes of areas with limits (Morning / Day / Evening / Night):
- Class AA (hospitals, schools): $50/45/40\,\text{dB}$
- Class A (residential): $55/50/45\,\text{dB}$
- Class B (commercial): $65/60/55\,\text{dB}$
- Class C (light industrial): $70/65/60\,\text{dB}$
- Class D (heavy industrial): $75/70/65\,\text{dB}$
Measurement by ANSI S1.4-1974 compliant sound level meter

Noise Management Options

Legal / Administrative
- Emission standards for vehicles, machinery
- Zoning, noise mapping, immission standards
- Enforcement (speed limits, hours‐of-operation rules)
Engineering
- Source modification: quieter engines, tyre profiles, mufflers
- Transmission reduction: enclosures, noise barriers, orientation of buildings
- Passive protection: ear plugs, façade insulation
- Land-use planning: minimum setback distances, greenbelts
Education & Information
- Public awareness campaigns
- Behaviour change: reduced horn use, lower driving speeds
- Training of noise experts, R&D funding

Typical Engineering Controls on Site

Redesign equipment speed/force; fit intake & exhaust mufflers
Routine maintenance & lubrication
Isolate or enclose noisy machinery; add damping pads
Sound-absorbing baffles, acoustic panels
Air-traffic noise: building insulation, curfews, greenbelts
Noise Barriers (soundwalls/berms)
- Exterior structures blocking line-of-sight
- Effective for highways, rail, industry

Soil Pollution Controls

Erosion prevention
- Contour cultivation (plowing/planting along elevation contours)
- Strip cropping (alternating erosion-prone & erosion-resistant crops)
- Terracing, diversion channels
Proper solid-waste disposal: sanitary landfills for residuals
Sustainable agronomy
- Use organic fertilizers; limit toxic pesticides
- 3Rs: reduce, reuse, recycle waste streams
Phytoremediation
- Sunflowers remove heavy metals (Pb, U) from soil
- Water hyacinths absorb chemicals in wastewater

Green Building & Sustainable Development

Green (Sustainable) Building Definition

Structures designed to reduce environmental impact via energy & water efficiency, waste minimization, healthy materials
Common rating systems: LEED, BERDE

Rationale

Lower carbon footprint and operating costs
Enhanced occupant well-being & productivity

Five Key Design Principles

Energy Efficiency / Environment
- Shading devices, natural ventilation, efficient appliances, LED/controls
- Renewable energy: daylighting, passive solar, PV, geothermal
- Zonal lighting control for perimeter daylighted areas
Water Quality & Conservation
- Dual plumbing for recycled/rainwater toilet flushing
- Ultra-low-flush fixtures, waterless urinals, low-flow heads
- Point-of-use water heating, leak elimination, onsite bio-treatment
Sustainable Materials
- Reuse existing components, specify rapidly renewable (bamboo, cork)
- Optimise engineered composites, avoid toxic/non-recyclables
Waste Reduction
- On-site segregation & recycling, life-cycle product selection
Indoor Environmental Quality
- Low/zero-VOC materials, designated smoking areas
- Fresh air purge, new filters, duct cleaning
- Natural lighting, operable windows, acoustic control

Benefits

Financial: reduced capital & O/M costs, risk reduction, tax incentives
Environmental: less resource depletion, healthier ecosystems
Social: stronger communities, raised awareness

Philippine Case Studies

Asian Development Bank HQ (Mandaluyong) – LEED Gold; rainwater harvesting; solar covers $\approx3.5\%$ of electricity
Arthaland Century Pacific Tower (Makati) – first certified net-zero; double glazing, sensor-based HVAC, rainwater reuse
Zuellig Building (Makati) – LEED Platinum; Low-E glass covering $90\%$ façade; saves $\sim29\times10^{6}\,\text{L}$ water yr⁻¹

Sustainable Development Goals (SDGs)

UN 2015 agenda – end poverty, protect planet, ensure prosperity by 2030
Definition of sustainable development: meeting present needs without compromising future generations

Drivers for SD

Persistent poverty and basic unmet needs
Rising living standards and consumption
Population growth + unequal resource distribution
Over-extraction of non-renewables, biodiversity loss, pollution

Three Pillars

Social (People)
Economic (Prosperity)
Environmental (Planet)

Environment & Health-relevant SDGs

SDG 3 Health – links to pollution burdens
SDG 6 Water & Sanitation – WASH, wastewater
SDG 11 Sustainable Cities – air, solid & chemical waste
SDG 12 Responsible Consumption – resource efficiency, waste
SDG 13 Climate Action – temperature, precipitation changes
SDG 14 Life Below Water – marine ecosystems
SDG 15 Life on Land – terrestrial biodiversity