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39 Cards in this Set
- Front
- Back
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Edwin Chadwick
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(1842) demonstrated a higher rate of disease in poverty-stricken laborers
- He suggested that the diseases were associated with the filth of the abominable living conditions of those workers - He suggested that their diseases were preventable through better sanitation |
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“The Great Sanitary Movement”
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Construction of sewers of smooth ceramic pipes and sufficient water to flush sewage to a distant depository
- That costly plan was rapidly implemented in London following the cholera epidemics of 1848 and 1853 |
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CONTAMINATED
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Containing chemical poisons, biological poisons, or infectious agents [viruses, bacteria, protozoans]
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POLLUTED
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Contaminated water in which the contamination is obvious
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POTABLE
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Water that is fit for consumption [it is usually low in organic content, but it still may contain a few thousand bacteria per mL]
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natural adsorption-biological predation process
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As water flows in gravel beds and fractured rocks below the surface soil -
- Disease-causing organisms and organic matter are removed by adsorption and trapping as they move through the subsurface - Microbial predators use trapped pathogens as food • Humankind’s Potable Water Purification and Wastewater (Sewage) Treatment mimic the natural adsorption-biological predation process |
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Bacteriological (Sanitary) Analysis of Water
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“Ideal” indicator organism
- Suitable for analysis of all types of water - Present whenever enteric pathogens are present - Survives longer than hardiest enteric pathogen - Does not reproduce in contaminated water - Detected by highly specific test - test easy to do and sensitive - Harmless to humans - Its level in water reflects degree of fecal pollution |
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FECAL COLIFORMS
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- Facultative anaerobic, gram-negative, nonsporing, rod-shaped bacteria that ferment lactose with gas formation within 48 hours at 35°C (Escherichia coli, Enterobacter aerogenes, Citrobacter freundii and Klebsiella pneumoniae)
- They are the most commonly used “INDICATOR ORGANISMS” of possible fecal contamination, because they are normally found only in the intestinal tracts of humans and other warm-blooded animals |
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INDICATOR ORGANISMS
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(Escherichia coli, Enterobacter aerogenes, Citrobacter freundii and Klebsiella pneumoniae)
- They are the most commonly used “INDICATOR ORGANISMS” of possible fecal contamination, because they are normally found only in the intestinal tracts of humans and other warm-blooded animals |
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FECAL ENTEROCOCCI
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Normally found only in the intestinal tracts of humans and survive better than E. coli in brackish and marine waters
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MEMBRANE FILTRATION TECHNIQUE
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a test used to determine contaminated water. Most water testing facilities use the MEMBRANE FILTRATION TECHNIQUE - a presence-absence (P-A) test
- Concentration of microbes from a 100-mL sample onto membranes [using a pore-size of 0.45 µm] - The membranes are incubated on an appropriate differential/selective medium, e.g. Levine’s Eosine Methylene Blue Agar [EMB] or Enterococcus Agar - Incubation at 44.5oC - 1 cfu of an indicator organism per 100 mL is an indication of contaminated water |
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DEFINED SUBSTRATE TESTS
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More recent tests are the DEFINED SUBSTRATE TESTS - 100 mL water samples are added to broth medium containing ONPG and MUG
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MULTIPLE-TUBE FERMENTATION TEST
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Traditional method detection - MULTIPLE-TUBE FERMENTATION TEST - a presumptive test
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Purification of Potable Water
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There are 3-4 basic steps in the purification of water from surface waters.
SEDIMENTATION FLOCCULATION FILTRATION DISINFECTION |
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SEDIMENTATION
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SEDIMENTATION of suspended materials( the depositing especially by mechanical means of matter suspended in a liquid)- This occurs in large sedimentation basins or reservoirs
- Additional aeration precipitates iron and manganese |
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FLOCCULATION
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FLOCCULATION - Powdered chemicals (alum [aluminum sulfate], lime, iron sulfate, or organic polymers) are added to the water
- These together with the microbes and organic molecules in the water aggregate into gelatinous masses [called “flocs”] - The flocs sediment out of the water in settling basins - This step removes many microorganisms (including viruses), organic matter, toxic contaminants, and suspended fine particles |
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FILTRATION
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FILTRATION - flocs, microbes, and fine particles are physically trapped within sand or gravel filters
- This removes >99% of microbes from water • Fast [rapid] sand filters -200 million gal/acre/day, but do not remove: - Giardia cysts “[traveler’s disease” - “backpackers disease” - “beaver fever”, most common water-borne pathogen in USA] - Cryptosporidium - Small protozoan with oocysts [self-limiting diarrhea, unless an individual is immunocompromised - Milwaukee, 1993] - Cyclospora [protozoan, self-limiting diarrhea] - Viruses - Up to 99.9% are removed by usual purification schemes, but this not considered sufficient protection • Slow sand filters - 3 million gal/acre/day - Rely on a microbial “Biofilm” on the sand grains which effectively removes ALL pathogens |
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DISINFECTION
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DISINFECTION - Chlorination [or Ozonation in Europe]
- Most microbes die within 30 min when chlorine gas is added so that there is a “residue” of 0.2-1.0 ppm - Concern about disinfection by-products (DBPs) such as trihalomethanes (THMs) which may be carcinogens |
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Two additional steps to the purification of water.
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• Softened, i.e. removal of Mg++ and Ca++ which precipitate, clog pipes and interfere with the action of soaps and detergents
• Fluorinated to prevent tooth decay |
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BIOLOGICAL OXYGEN DEMAND -BOD
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A critical measurement of water pollution-
- Measures the amount of dissolved oxygen needed for microbial degradation of organic matter (by naturally-occurring microbes) - An indirect measurement of the amount of organic material in a sample - A measurement of the amount of O2 that is required to decompose the organic matter that is present in the water sample, by the bacteria that are already present in the sample - The test is a comparison of the concentration of dissolved O2 in one sample immediately after collection versus the O2 in a parallel sample that was incubated at 20°C for 5 days - Can be affected by presence of ammonia |
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Sewage Treatment = “Wastewater” Purification
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Wastewater can contain high levels of organic matter and human pathogens - These can be removed (or their amount decreased) by wastewater treatment
- Such treatment is one of the most important factors in maintaining public health • Treatment is an controlled intensification of natural degradative processes • Basic principle - Water is removed from the total wastes - Then heterotrophic microbes degrade the solid waste • It’s intended to minimize environmental damage and to destroy pathogens • The simplest system is the Oxidation Lagoon which may require up to 3 months to purify sewage • Large-scale sewage treatment is performed in the large basins of Treatment Plants or in Constructed Wetlands • Home treatment systems use either Cesspools or Septic Systems, but pathogens are not directly killed in these treatment facilities |
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PRETREATMENT
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first step in Treatment of Raw (Untreated) Sewage. PRETREATMENT - Removal of grit and insoluble materials via filter grids
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PRIMARY TREATMENT
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second step in Treatment of Raw (Untreated) Sewage. PRIMARY TREATMENT - Sewage is physically treated with alum
• The settling of “flocs” removes particulates and 20-30% of the BOD • The solids (called “Sludge”) are dried and: dumped, or incinerated, or biologically treated [step 5] |
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SECONDARY TREATMENT
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Third step in Treatment of Raw (Untreated) Sewage. SECONDARY TREATMENT - Organic compounds are oxidized via BIOLOGICAL treatment with a complex community of microbes
- The bacterium Zoogloea sp. produces polysaccharides that further flocculate the sewage • Oxidation is enhanced by mixing in “Aeration Basins” or by passage of the sewage over rock beds that are colonized with a microbial “Biofilm” • This step removes 90-95% of the remaining BOD and additional particulates • This step removes many bacterial pathogens • Secondary treatment produces - - A liquid containing organic compounds, which may be filtered and “dumped” - And a solid called ACTIVATED SLUDGE which is swarming with microbes; this is dried and dumped, or incinerated, or biologically treated [step 5] - Some of the sludge is also used to “inoculate” subsequent batches of waste water |
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ADDITIONAL SECONDARY TREATMENT
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fourth step in Treatment of Raw (Untreated) Sewage. ADDITIONAL SECONDARY TREATMENT
• Anaerobic digestion in large fermentation tanks for up to 30 days • Much of the biomass of sewage sludge can be converted into methane • The resulting Sludge can be easily dried, but it may contain high concentrations of heavy metals and other chemical contaminants that may have been in the sewage - This sludge has been successfully used as fertilizer by the lumber industry, but should NOT be used as fertilizer for feed crops |
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TERTIARY TREATMENT
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five step in Treatment of Raw (Untreated) Sewage. TERTIARY TREATMENT - Expensive chemical treatments [e.g. flocculation, filtration] or additional biological processing to “completely” purify the liquid portion of secondary treatment - i.e. to remove the N/P that cause eutrophication of aquatic environments
• Pseudomonas spp. will denitrify ammonia, if provided with organic carbon [e.g. methanol] • Acenetobacter spp. carry out “luxurious uptake” of phosphate [accumulation in excess of metabolic needs] |
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Homeowner’s Septic System
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- It typically consists of:
• 1000-2000 gallon concrete box - Anaerobic digestion and sludge sedimentation occurs in the “SEPTIC TANK” - Note that the organic matter that settles is not absorbed into the ground and septic tank “pumpage” must be pumped out regularly! • The liquid portion of wastes is drawn off from the septic tank by the “OUTLET PIPE” • And distributed [via the “D BOX” (distribution box)] into the “LEACH FIELD” - A series of perforated pipes on gravel and fractured rock beds in the surrounding soil - Aerobic digestion, adsorption, and filtration of organic material are accomplished by microbial processes drainage through the leach (drain) field - Organic materials are adsorbed, filtered, and oxidized |
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Constructed Wetlands
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are currently used to process industrial wastes and waters from abandoned mines, etc. - organic matter, inorganic matter and metals
• They are a mixed community of floating, emergent, and submerged plants and the associated microbes - Facilitate the processing of dissolved nutrients • The plant/microbe associations can be “tailored” to degrade a particular waste being processed [e.g. Promotion of anaerobic conditions in the root zone allows growth of Desulfovibrio sp. which produce sulfides that trap metals] |
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Landfills versus Composting...
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*Composting allows for controlled decomposition and produces physiologically stabilized compost material. This material, when added to the soil, increases the organic content without stimulating soil microorganisms to increase decomposition.
*Composting allows for controlled decomposition and produces physiologically stabilized compost material. This material, when added to the soil, increases the organic content without stimulating soil microorganisms to increase decomposition. *In situ treatment procedures for groundwater are under investigation; microorganisms are critical in many of these remediation efforts *Composting allows for controlled decomposition and produces physiologically stabilized compost material. This material, when added to the soil, increases the organic content without stimulating soil microorganisms to increase decomposition. |
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Dental Infections
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• caused by various odontopathogens
• formation of dental plaque creates environment for pathogens that produce acids and other virulence factors |
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Dental Plaque
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• acquired enamel pellicle
– formed when enamel adsorbs acidic glycoproteins from saliva – colonized by various bacterial species to form plaque • coaggregation – attachment of different species of bacteria to each other – based on cell-to-cell recognition |
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Dental Decay (Caries)
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demineralization/remineralization cycle
– production of acids leads to release of calcium and phosphate ions from enamel followed by remineralization – when demineralization > remineralization, caries results • treatment, prevention, and control – no drugs available for treatment – good dental hygiene and minimal ingestion of sucrose |
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Periodontal Disease
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• diverse group of diseases that affect periodontium
– supporting structure of tooth • initiated by formation of subgingival plaque • main species involved is Porphyromonas gingivalis |
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periodontitis
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– initial inflammatory response to plaque bacteria and tissue destruction
– leads to swelling of tissue and formation of periodontal pockets – bone destruction caused by colonization of periodontal pockets |
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gingivitis
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– inflammation of gingiva caused by colonization of periodontal pockets
• treatment, prevention, and control – oral surgery and antibiotic therapy in some cases – plaque removal and good dental hygiene |
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Total Organic Carbon (TOC)
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- Quantifies all carbon
- Organic matter oxidized at high temperature - Amount of CO2 produced is measured - Fastest, but less informative |
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Chemical Oxygen Demand (COD)
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- Quantifies organic matter (except lignin)
- Organic matter reacted with strong acid (permanganate) - Slower test - High cost for chemical waste disposal |
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Nitrogen Oxygen Demand
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- Use of oxygen during nitrification process
- Inhibited by addition of chemicals to sample |
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The “Death” of a River
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- Algae “bloom”
- Their increased population and the associated bloom of microbes deplete the water of O2 - Dead organisms accumulate of the bottom - Anaerobic microbes thrive and produce gases that give the water a “stench” |
