MS312: Sources of pollution Oxygen consuming wastes - PowerPoint PPT Presentation

Title: MS312: Sources of pollution Oxygen consuming wastes


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MS312 Sources of pollution Oxygen consuming
wastes

• What are oxygen consuming wastes?
• Effluents from Sewage, Food Processing, Urban
  runoff
• They are all rich in organic compounds
• Many cause eutrophication and siltation

Read Clark Ch 3 Oxygen Consuming Wastes
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Looking ahead

• Oil Pollution
• Heavy Metals
• Pesticides, PCBs Halogenated hydrocarbons
• Radioactivity
• Dredgings, solids, plastics, heat
• Case studies and guest speakers
• Symposium Your investigations in Marine
  Pollution

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Oxygen Demanding Wastes

• Measurement of oxygen demand
• Standard measure - 5-day BOD (biochemical oxygen
  demand)
• Easily done - change initial oxygen concentration
  - final oxygen concentration, in the dark, at
  20oC
• BOD ranges from about
• 0-1 for uncontaminated natural waters,
• 2-5 for forest and cropland
• 100-300 Treated domestic sewage
• 500 - 1000 for raw sewage
• Food processing 750 mg/L
• Paper mills 375 mg/L

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Sewage, garbage, organic wastes

• The major pollutant in most areas worldwide is
  just plain sewage.
• This is especially so in the South Pacific, where
  there are few industrial sources.
• In many places there is also very little water,
  so the problem of sewage is more difficult to
  solve

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Sewage

• Origin and characteristics
• greywater vs blackwater
• To treat or not to treat?
• Primary treatment
• Secondary treatment
• Tertiary treatment
• Ocean outfalls

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Sewage treatment
primary
secondary
tertiary
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Kinoya(also Raiwaqa) as an example of secondary
sewage treatment
primary clarifiers
trickling filters
humus tanks
digester
to sea
lagoon
in from sewer
sludge
drying beds
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First and Second Stage Sewage treatment
Kinoya, May 2005 Primary Sludge
settling Secondary Trickling filter
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Alternatives methods in sewage treatment
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Sewage and public health

• The common test for sewage pollution is an assay
  for faecal coliform bacteria.
• Coliform bacteria are not usually harmful - but
  the indicate the potential presence of pathogens
• Many bacteria and viruses can cause annoying
  diarrhea and skin infections.
• A few, like the waterborne causative agents of
  cholera dysentery and typhoid fever are extremely
  serious.

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Pathogens potentially waterborne and water
contact the list is long, and includes bacteria,
viruses, protozoa and helminths (parasites)
See on share files PathogensPotentiallyWaterborne
.doc and PathogensWaterContact.doc
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Some important water borne pathogens

• Bacteria
• Aeromonas hydrophilia, Campylolbacter spp.
  Clostridium perfringens, E. coli, Francisella
  tularensis , Klebsiella pneumoniae, Plesionionas
  shigelloiides Pseudomonas aeruginosa , Shigella
  spp. All cause Diorrhea or Gastroenteritis
• Staphylococcus aureus, Clostridium
  perfringens Wound and skin infections
• Salmonella typhi Typhoid fever
• Vibrio cholerae Cholera

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Some important water borne pathogens ctd.

• Viruses
• Poliovirus Paralysis, encephalitis (not common
  because of vaccination)
• Hepatitis A Infectious hepatitis type A
• Protozoa
• Giardia lamblia Giardiasis - mild, acute, or
  chronic diarrhea
• And many more.

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Contamination ofSuva Harbour - Creeks
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Contamination of Suva Harbour - Shore
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Kiribati is a case where there is little water,
and many people
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FC in Kiribati is harming people and fisheries
Kelly, David J (1994) The effects of domestic
waste on marine and groundwater quality in Tarawa
Atoll, Republic of Kiribati. IAS, USP, Suva, Fiji
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The great dead sea of New Jersey
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The great dead zone of the Mississipi River

• An anoxic zone is created in the bottom waters of
  the Mississipi River delta by runoff from sewage
  and agriculture
• It varies according to river flow.

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Organic wastes sugar cane and food processing

• One major effect of organic wastes is oxygen
  depression.
• In extreme cases, oxygen may be so low as to make
  life for fishes impossible.

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Classic case oxygen in Thames River
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The fish have returned!
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Ba River and FSC Rarawai
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Rainfall and river flow at Ba
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Ba River oxygen
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Ba River FC bacteria
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Ba River surface oxygen
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Urban runoff

• In built-up areas of major towns, there is a high
  proportion of impermeable land (pavement,
  buildings).
• This increases the flow of water directly to
  creeks and rivers.
• The added flow, without benefit of percolation
  through the soil, carries with it a rich mixture
  of pollutants oil, heavy metals, pesticides,
  eroded soil.

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Siltation

• Land disturbance, whether from urban development,
  farming or logging, exposes the land to
  weathering and erosion.
• When the land is near the sea, silt can be
  carried into the ocean.
• There, it may blanket or smother filter feeding
  organisms.
• Corals are especially susceptible to to the
  effects of siltation and eutrophication

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Eutrophication

• Too much of a good thing, is a bad thing!
• The simple nutrients necessary to support
  photosynthesis can also cause overgrowth of
  plants.

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Eutrophication - effects

• Eutrophication causes changes community
  structure, mostly for the worse.
• In extreme cases all oxygen may be consumed.
• The bottom will then become anoxic.
• An anoxic bottom is unable to support normal
  life.
• Anoxia is accompanied by high H2S, which is
  toxic.
• Long before the bottom becomes anoxic, plants
  (algae) will be encouraged to grow.
• The algae overgrow corals, and the corals die.
• Along with the corals, fish die or are replaced
  by less desirable species.

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Eutrophication Effects on a Coral Reef Kaneohe
Bay, Oahu, Hawaii

• Problem progressive deterioration of reef
• Description of degraded ecosystem
• Identification of causes
• Intervention
• Outcome
• Lessons

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Problem progressive deterioration of the reef

• Setting NE coast Oahu
• 1928 high natural, recreation value, and
  accessibility to population recognised.
• 1945 corals abundant and diverse, some increase
  in biomass, productivity, localised replacement
  by Dyctyosphaera cavernosa (green bubble alga)

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Edmondson in 1928

• "Kaneohe Bay is one of the most favorable
  localities for the development of shallow water
  coral. Nearly all of the reef-formig genera known
  in Hawaii are represented and many species grow
  luxuriantly"
• Edmondson, CH. 1928. Ecology of a coral reef.
  Bishop Mus. Bull. 45 (64p)

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Kaneohe Bay Location
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Description of degraded ecosystem

• 1939-1963 population increase leads to
  construction of sewerage system, outfalls into SE
  bay.
• 1965 major reef kill caused by high rainfall,
  rapid runoff
• progressive anoxia in sediments, algal
  overgrowth
• 1977 99.9 dead coral SE sector, benthos
  composed of detritivores and filter feeders.

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Kaneohe Bay Progressive deterioration, and
recovery
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Outcome and Lessons

• What happened?
• 1992 recovery substantially as 1988 (4 yr)
• Low Salinity by itself less effect than
  nutrients and algae.
• Recovery to pristine? Or to 1945?
• Lessons
• Algal growth encouraged by eutrophication is
  persistent (10yr)
• FW damage to corals is intense but limited to
  upper layers, and recovery faster (4 yr)

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Happy Coral Leeward Reef
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Coral Eutrophication by Algae, Indonesia
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Coral Algae Philipines
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Coral Eutrophication
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Coral Bleaching GBR
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Coral Silted Philippines
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Fijis Coral Coast a victim of its own success

• Along Fijis Coral Coast, excess nutrients (N and
  P species) are causing eutrophication.

• The Coral Coast (SE Viti Levu) has been developed
  as a mecca for tourism.
• With tourism has come increased population,
• increased incomes,
• And flush toilets
• The result is an overgrowth of Sargassum, a brown
  alga.

Islands Business and Fiji Islands
Business http//www.islandsbusiness.com/islands_bu
siness/

• The sources are Villages, Piggeries and Resorts
  in that order.

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Eutrophication REDOX Chemistry and Anoxia
,

• Biological Oxygen Demand (BOD) is a measure of
  how much oxygen is consumed by living water,
  mostly bacteria and other microbes, over 4 days
  in the dark. It is a measure of respiration.
• Typical Biological Oxygen Demand (BOD) Values
  (in mg O2 /L wastewater)
• 0-1 for uncontaminated natural waters,
• 2-5 for forest and cropland
• 100-300 Treated domestic sewage
• 500 - 1000 for raw sewage
• Food processing 750 mg/L
• Oxygen concentration in
• HEALTHY WATER 6-8 mg/L (depending on water
  temperature
• FISH ABSENT 2 mg/L

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Degradation sequence Oxygen to H2S and Methane

• What happens if O2 is exhausted, but there is
  still organic material present?
• A succession of microbially (or chemically)
  mediated reactions happens next, and some have
  very important environmental consequences
• 1. Aerobic Respiration
• O2 CH2O CO2 H2O
• Oxidation of organic matter by oxygen
• Common in environments with plenty of O2
• WHAT NEXT?

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Next steps after oxygen

• 2. DENITRIFICATION
• 4NO3- 5CH2O 4H 5CO2 2N2 7H2O
• 3. MANGANESE REDUCTION
• 2MnO2(sw) CH2O 4H 2Mn2(aq) CO2 3H2O
• May release toxic trace metals (Mn and
  associated metals)
• Oxidation of organic matter using nitrate
• 4. IRON REDUCTION
• 4Fe(OH)3(s) CH2O 8H 4Fe2 (aq) CO2
  11H2O
• May release toxic trace metals (Fe and metals)
• May release phosphorous (a limiting nutrient)

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And then

• 5. SULFATE REDUCTION
• 1/2 SO4-2 CH2O H ½ H2S CO2 H2O
• Common in marine environments
• Produces toxic hydrogen sulfide gas
• Resulting sulfide minerals can scavenge metals
• 6. METHANOGENESIS (FERMENTATION)
• CH2O CH2O CH4 CO2
• Common in severely eutrophicated waters, swamps,
  rice paddies, other flooded freshwater systems
• Produces methane (an important greenhouse gas!)

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End oxygen demanding wastes

• The most important pollultion challenge facing
  the inshore areas of the world oceans are sewage
  and eutrophication