Fermentation Test (Phenol Red)

John Snow’s Cholera Spot Map

Environmental MicrobiologyEnvironmental 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 waterNew York City: 20 years later

http://www.kingcounty.gov/environment/wastewater/CSO/FAQ.aspx

American waste amounts: (per person per day)

150 gal water120 gallon of waste

5lbs trash

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. Determine O2 levels 2. Incubation with microbes (5 days/20°C)3. Determine O2 levels 4. Calculate difference between 1 & 3

BOD Organic

Matter (waste)

B.O.D. Effects

Raw sewage BOD: 300 to 400 mg/literNatural 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/4-5-12/21351.html

“200 million liters of sewage and industrial waste, much of it untreated, ooze into the Ganges from Varanasi”

-Richard Stone, Science 2011

Multi-series process (US)• 1° treatment

• 2° treatment (4 methods)• Advanced Treatment

Large Scale Wastewater 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 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

Anaerobic Sludge Digestion

2° Treatment

• Eliminates most of remaining BOD

• Microbial degradation of organic material

• 4 different options

Aerobic organisms degrade organic material to C02 and H2O

1. Activated sludge- commonly used Aerobic microbes (grown in flocs)Requires innoculation & aerationResedimentation(save floc, treat sludge)

2. Trickling filter- smaller treatment plants Spray sewage over biofilmof aerobic microbes

2° Treatment Methods

• 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 processesPhysical, chemical or biological processesIncreased expense over 1° and 2 ° treatmentIncreased 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

Performed before effluent is discharged• Chlorine• Ozone• Ultraviolet light

Disinfection

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 Improper drainage

Presence of pathogens Toxic conditions

Water-borne disease

Salmonella typhimurium

Vibrio cholerae

Leigeonella species

Clostridium botulinum

Escherichia coli

Rotavirus Hepatitis A

Polio virus

Giardia lambliaEntomoeba histolytica

Cryptosporidium parvum

Macha, Zambia

Waste and Water in Underdeveloped countries

Pit latrine versesComposting toilets

Ground Water: a clean source of drinking water?

1. Sedimentation

2. Flocculation of organic material

3. Filtration Removal of microorganisms

Chemical absorption

4. Disinfection

Drinking Water Treatment Process (US)

Test for indicator organisms: coliforms

Drinking Water Testing (US)

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