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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
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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 • Determine O2 levels • Incubation with microbes (5 days/20°C) • Determine O2 levels • Calculate difference between 1 & 3 BOD Organic Matter (waste)
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/4-5-12/21351.html “200 million liters of sewage and industrial waste, much of it untreated, ooze into the Ganges from Varanasi” -Richard Stone, Science 2011
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 • 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 Improper drainage Presence of pathogens Toxic conditions
Water-borne disease Giardia lamblia Entomoeba histolytica Cryptosporidium parvum Salmonella typhimurium Vibrio cholerae Leigeonella species Clostridium botulinum Escherichia coli Rotavirus Hepatitis A Polio virus
Waste and Water in Underdeveloped countries Pit latrine verses Composting toilets Macha, Zambia
Drinking Water Treatment Process (US) • Sedimentation • Flocculation of organic material • 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.