Download Review PPT

Review
Water Pollution
Major Water Pollutants
1. Human wastewater: sewage & gray water
• Decomposition of organic waste → Huge O2 demand
• Excess nutrients (N & P)  eutrophication
• Disease-causing organisms (esp. E. Coli & Cholera)
2. Metals (Pb, Hg, As, Cd)
3. Acid – rain, deposition, runoff
4. Synthetic Organics (pharma; pesticides; Military & Industrial
compounds)
5. Oil
6. Solid Waste (especially plastic!)
7. Sediment - erosion - turbidity
8. Thermal & Noise pollution
• Water Pollution:
• Point Sources - Discharge pollution from specific locations (single point). EASY TO
MONITOR/REGULATE
• Effluent
• Factories, power plants, oil wells
• Non-Point Sources - Scattered or diffuse, having no specific location of discharge.
HARDER TO CONTROL!!
• Agricultural fields, feedlots, golf courses
Disinfect:
Chlorine
Ozone
U.V. light
Primary sewage treatment: a
physical process that uses screens
and a grit tank to remove large
floating objects and allows
settling.
Tertiary Step
Usually not present
Expensive
Added to remove specific pollutant
usually N & P
Secondary sewage treatment: a biological process
in which aerobic bacteria remove as much as 90%
of dissolved and biodegradable, oxygen demanding
organic wastes.
•.
Water Quality Indicators
• Know your list – be able to give examples / sources / causes / effects
• N&P
• Biodiversity: macroinvertebrates, fish, plants, amphibians, algae, bacteria
• DO / BOD / CO2
• Fecal coliform – indicator
• Temp
• Turbidity
• Heavy metal / pH – how linked?
• Color / odor
• Synthetic Organic Compounds – Pesticides
• Gender benders
•
•
•
•
Pharmaceuticals – antibiotics, hormones
Ammonia
Chlorine
Hardness
Eutrophication
• Natural vs. Cultural
• Oligotrophic: nutrient-poor water
• Eutrophic: nutrient-rich water
• Sources - agricultural runoff (fertilizer, feedlots), detergents (P only), disturbed soil,
products of decomposition (so any organic matter)
• Indicators • Elevated N and P levels
• Decreased DO levels, increased BOD levels
• Cloudy water: from algae and cyanobacteria
• Effects – Eutrophication  nutrients ↑, algae grows, blocks sunlight, dies and
decomposes, O2 ↓
• Dead zones
Gulf of Mexico Dead Zone
Worst in summer
Affects fish & shrimp
harvests
Milk Lab
Be able to describe in detail what happened & why
Farm or animal feedlot
Be able to describe impact of runoff
Oxygen Sag Curve
A.
Clean Zone
• DO high
• BOD low
demand
B. Pollution enters stream
C. Decomposition Zone
• DECOMPOSITION increases to break down pollution
• OXYGEN decreases as it is used up by decomposers
D. Septic zone – DEAD ZONE - Hypoxic
• dissolved oxygen levels are very low and very few species can survive
E. Recovery Zone
• Waste concentrations decrease
• DO , BOD 
F. Clean Zone
• DO is high, BOD is low and normal biodiversity levels are present.
Clean Water Act - 1977
• EPA to set water quality standards for industry and for all
contaminants in surface waters
• regulates discharges of pollutants in the US - point sources
• Requires a permit to discharge any pollutant into a
navigable waterway.
• Goal: Make lakes & streams fishable & swimmable
• sets daily limits for total pollutant discharges
• Total Maximum Daily Load (TMDL)
Safe Drinking Water Act - 1974
• established to protect the quality of drinking water in the U.S
• All waters designed for drinking use - above ground or underground
sources
• EPA sets Maximum Contaminant Levels (MCLs) for drinking water
• Standards for dozens of contaminants