Environmental Technology

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Environmental Technology

• Wastewater Management
• Module 6.0

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Historically...

• In 1848 in London, England 14,600 people died of
  cholera and dysentery
• In 1856 in London, England 10,675 people died of
  cholera and dysentery
• ..a pattern maybe?
• human wastes were contaminating the citys water
  supply

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Obj 6.1 Wastewater defined...

• ...is used water, or
• the water supply of a person and/or community
  that has been used for a variety of purposes

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Obj 6.1 Wastewater Strength

• BOD
• TSS
• Nitrogen
• Phosphorus
• Pathogens

• Untreated sewage is about 99.9 water and only
  0.1 impurities and solids

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Wastewater Strength

• Biochemical Oxygen Demand high demand indicates
  lots of organics and micro-organisms
• Total Suspended Solids typically only 0.1 of
  total sewage

• BOD
• TSS

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Wastewater Strength

• compounds of Nitrogen such as ammonia, nitrites,
  and nitrates (35mg/L)
• Phosphor compounds such as phosphates (10mg/L)

• Nitrogen
• Phosphorus

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Wastewater Strength

• Protozoa, bacteria, and other disease causing
  organisms
• E.coli indicative of human waste
• detected by Coliform test

• Pathogens

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Obj 6.2 Contributors to Sewage Flow

• residential land uses (sanitary sewage)
• commercial/institutional land uses (sanitary
  sewage)
• industrial/manufacturing land uses (industrial
  sewage)
• infiltration into sewer system
• stormwater (for combined sewers)

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Obj 6.4 Storm vs Sanitary Sewers?

• Similarities
• both are converging systems
• both use pipes and manholes
• both use Mannings Equation to examine flow
  characteristics

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Obj 6.4 Storm vs Sanitary Sewers?

• Differences
• Inflow storm sewers open to air
• sanitary sewers are closed to air.
• Outflow storm sewers are fragmented and with
  several discharge points
• sanitary sewers are continuous leading to a
  sewage treatment plant

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Combined Systems

• Some cities still have combined storm and
  sanitary sewers
• if system overflows during heavy rains, raw
  sewage gets into natural watercourses
• combined sewer overflow (CSO) storage tanks
• (Figure 8.1 Nathanson)