Biological Water Quality Problems

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Biological Water Quality Problems

• The Greatest Historical Concern in Water Quality
• 5-million people die annually in the world from
  water-bourn diseases (Ongley, 1996)
• Bacteria, viruses, protozoa
• Most common source is inadequately treated human
  wastes
• Most pathogenic microorganisms cant survive long
  in the environment outside the host

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Microbiology Definitions

• Heterotroph- an organism capable of deriving
  carbon for growth and cell synthesis from organic
  compounds generally also obtain energy and
  reducing equivalents from organic compounds
• Phototroph- an organism able to use light as a
  source of energy.

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Microbiology Definitions

• Deoxyribonucleic acid (DNA)- polymer of
  nucleotides connected via a phosphate-deoxyribose
  sugar backbone the generic material of a cell
• Ribonucleic acid (RNA)- polymer of nucleotides
  connected via a phosphate ribose backbone,
  involved in protein synthesis

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Microbiology Definitions

• Bacteria- single celled plants which are motile.
• Require a high moisture environmentIngest only
  soluble compounds that diffuse through the cell
  wall
• Most are not photosynthetic, though some are
• Typical size 0.5 to 3 microns
• Enteric Bacteria- Bacteria that inhabit the
  intestinal tract of humans and other animals.
  Indicators of fecal pollution

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Microbiology Definitions

• Aerobic Bacteria- Require free oxygen in the
  environment
• Anaerobic Bacteria- Use inorganic compounds in
  their metabolism. Free oxygen is toxic to these
• Facultative- Can use free oxygen, but dont
  require it for their metabolism.

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Microbiology Definitions

• Algae- single or multi-celled plants that mostly
  live in water
• Photosynthetic.
• Algal blooms- N P are limiting nutrients
• Protozoa- single celled animals,
  non-photosynthetic, motile and predatory some
  species form cysts and oocysts tolerant of harsh
  environments including some water treatment
  methods such as chlorination

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Microbiology Definitions

• Virus- An ultramicroscopic single celled plant
  that replicates itself only within cells of
  living hosts
• A piece of nucleic acid (DNA or RNA) wrapped in a
  thin coat of protein.
• Many are pathogenic
• Size 20 to 30 x 10-9m (20nm to 30 nm)
• The smallest and hardest pathogens to filter from
  water not affected by antibiotics or chemical
  disinfectants

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Microbiology Growth Factors

• Q10 2 rule for 0 to 40 deg. C
• Optimum growth range 20-40 deg C
• Prefer Neutral pH
• Thrive best in moist, aerobic environment
• Moisture is essential for nutrient transport
• Optimum water potential 0.1 to 1 bar
• Need C,N,P,S,K in either organic or inorganic
  forms

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Factors affecting survival of Enteric Organisms
and other Bacteria in the Soil

• pH
• Porosity
• Organic matter content
• Texture and particle size distribution
• Elemental composition
• Temperature
• Moisture content
• Absorption and filtration properties
• Availability of nutrients

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Factors affecting survival of Enteric Organisms
and other Bacteria in the Soil

• Atmospheric Conditions
• Sunlight
• Moisture
• Temperature
• Biological competition for nutrients
• Predation
• Antibiotics from indigenous organisms
• Presence of Toxic Substances

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Bacterial Growth

• Under ideal conditions bacterial numbers can
  double every 20 minutes
• 1 bacterium could become 16,000,000 in 8 hours.

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Bacterial Growth Stages

• 1. Adapting to the environment (no growth)
• 2. Accelerating (arithmetic growth)
• 3. Logarithmic (exponential growth)
• 4. Limiting growth (limiting nutrients, oxygen or
  buildup of toxic wastes)
• 5. Stationary population densities of 2 x 10-9
  cells/ml
• 6. Death when limiting factors become lethal

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Bacteria in the Environment

• Bacteria are important for many beneficial
  processes in the natural environment
• Bacteria are important for many beneficial
  processes within the human body
• Bacteria cause the degradation of many wastes and
  toxic substances in the environment
• Bacteria are everywhere in the environment and we
  are constantly exposed to them

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Bacteria in the Environment

• Our natural defenses protect us from normal
  exposure to pathogens
• Concentrated exposure to pathogenic organisms
  normally are from contaminated food and water or
  at selected locations such as unclean restrooms
  and animal waste storage facilities

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Biological Water Quality ProblemsAgricultural
Related Sources

• Rural Septic Tank Leachate
• Land application of animal wastes
• Land application of human wastes
• Land application of sewage sludge
• Irrigation using water polluted with human wastes
• Washing fresh produce with water polluted with
  human wastes

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Fate and Transport of Pathogenic Organisms

• Most pathogenic organisms do not survive well
  outside of a host organism
• Natural microbial populations prey on pathogenic
  organisms in the natural environment
• Enteric bacteria typically last only a few days
  in the soil

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Fate and Transport of Pathogenic Organisms

• Transport processes are the same as for any
  chemical pollutant except that micro-organisms
  are not soluble, and therefore can not move
  through the soil if they are too big to pass
  through the pores, or if they are sorbed on the
  soil particles.
• Many pathogens are filtered out or sorbed in the
  soil profile

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Pathogens in Ground Water

• Most problems in aquifers less than 20m below the
  surface
• Problems in aquifers overlain by coarse material
  such as gravel and sand
• Problems in cavernous rock formations such as
  limestone or highly fractured rock
• Problems associated with poorly constructed wells

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Escherichia coli in the Environment

• E. coli a bacteria found in the intestinal tract
  of warm-blooded animals, including humans. (an
  enteric bacteria)
• Makes up 0.1 of the bacteria in fecal material
• A coliform bacteria which ferments lactose to gas
  within 48 hr when incubated at 35oC (making them
  easy to detect)
• Used as an indicator for the possible presence of
  fecal material in water

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Escherichia coli in the Environment

• E.coli are necessary for healthy functioning of
  our digestive systems
• Only one strain of E.coli (O157H7) causes
  diseases in humans
• The coliform test is a presumptive test
• A positive test for the presence of coliform
  bacteria does not prove that the water has been
  contaminated by pathogenic organisms

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Common Diseases associated with polluted water

• Amebiasis infection caused by amoebas.
• Ascariasis infection caused by parasitic worms
  in the human intestines
• Cholera caused by a bacteria. Frequently fatal
• Gastroenteritis any inflammation of the stomach
  or intestine
• Giardiasis caused by a protozoa
• Hepatitis A caused by a virus
• Typhoid caused by Salmonella typhi

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Pathogens in the Environment

• Most dont survive well outside a host
• Will not last long in the natural environment
  (except viruses)
• Will be filtered out in the soil profile (need at
  least 20m of soil to be sure)
• More possibility of problems in course overburden
  or cavernous or fractured rock overburden