Fermentation Test (Phenol Red)
John Snow’s Cholera Spot Map
Environmental Microbiology:
Treatment of Waste Water and
Polluted Habitats
08/09/11
Waste Water & Sewage
A little history
• Ancient Romans
• Modern sewage system
London: pipes and high pressure water
New York City: 20 years later
American waste amounts:
(per person per day)
150 gal water
120 gallon of waste
5lbs trash
http://www.kingcounty.gov/environment/wastewater/CSO/FAQ.aspx
Sewage Treatment
Purpose:
–Eliminate potential pathogens and toxins
–Decrease nutrient content (reduce microbial growth)
–Reduce B.O.D.
Biochemical oxygen demand (BOD):
Amount of oxygen required for microbial
decomposition of organic matter in sample
1.
2.
3.
4.
BOD
 Organic
Matter (waste)
Determine O2 levels
Incubation with microbes (5 days/20°C)
Determine O2 levels
Calculate difference between 1 & 3
B.O.D. Effects
Raw sewage BOD: 300 to 400 mg/liter
Natural water BOD: 5-10mg/L
If you dump raw sewage into “receiving water”, the
dissolved O2 can be quickly depleted by microbes
http://www.theepochtimes.com/news/4-512/21351.html
“200 million liters of sewage
and industrial waste, much of
it untreated, ooze into the
Ganges from Varanasi”
-Richard Stone, Science 2011
Large Scale Wastewater Treatment
Multi-series process (US)
• 1° treatment
• 2° treatment (4 methods)
• Advanced Treatment
Effluent (treated liquid) is
discharged in body of water
Sludge (solid) is further
treated in anaerobic
digester and disposed of
1° Treatment
Filter & settle steps remove
~50% of solids & 25% of BOD
Anaerobic Sludge Digestion
• Anaerobic organisms act on solids (sludge)
• Various populations act sequentially
Organic matter  organic acids, CO2, H2
Organic acids  acetate, CO2, H2
Acetate, CO2, H2  methane
• Remaining sludge dehydrated
• Disposal: incineration, landfill, fertilizer
2° Treatment
• Eliminates most of
remaining BOD
• Microbial degradation
of organic material
• 4 different options
Aerobic organisms degrade organic material to
C02 and H2O
2° Treatment Methods
1. Activated sludge- commonly used
Aerobic microbes (grown in flocs)
Requires innoculation & aeration
Resedimentation(save floc, treat sludge)
2. Trickling filter- smaller treatment plants
Spray sewage over biofilm
of aerobic microbes
•
•
•
•
•
Bacteria
Fungi
Algae
Protozoa
Nematodes
2° Treatment Methods continued
3. Lagoons- shallow ponds where photosynthetic organisms
create aerobic environment (treatment takes months)
4. Artificial wetlands
• Similar to lagoons
• Aerobic & anaerobic
environments
• Involves bacteria,
algae, plants,
sedimentation
• Habitat generation
Advanced Treatment
Physical, chemical or biological processes
Increased expense over 1° and 2 ° treatment
Removal of ammonia,
nitrates and phosphates
• Ammonia stripping: Liberates
gaseous ammonia from water
• Denitrification: use of bacteria
(creation of N2 gas)
• Chemical precipitation:
phosphate removal
Disinfection
Performed before effluent is discharged
• Chlorine
• Ozone
• Ultraviolet light
Purpose: reduce numbers of
microorganisms and viruses
Septic Tanks (Rural Areas)
Collection in large tank
– Settling of sludge
– Anaerobic degradation
Outlet to drainage field
– Aerobic oxidization of
organic material
Potential Problems:
Improper aeration
Presence of pathogens
Improper drainage
Toxic conditions
Water-borne disease
Giardia lamblia
Entomoeba histolytica
Salmonella typhimurium
Vibrio cholerae
Leigeonella species
Clostridium botulinum
Escherichia coli
Rotavirus
Hepatitis A
Cryptosporidium parvum
Polio virus
Waste and Water in
Underdeveloped countries
Pit latrine verses
Composting toilets
Macha, Zambia
Ground Water:
a clean source of drinking water?
Drinking Water Treatment Process (US)
1. Sedimentation
2. Flocculation of organic
material
3. Filtration
Removal of microorganisms
Chemical absorption
4. Disinfection
Drinking Water Testing (US)
Test for indicator organisms: coliforms
MPN Index:
Maximum for drinking water: 0/1000ml
(depends on collections per month)
Example: If collect 40 samples: <5% can be positive
If exceed positives/month must be reported
Activity
Read through “Ailing Ganges” article and
identify similarities and differences (3
total) between waste-water treatment in
India and in the US.
The Golden Horn of Istanbul