Human Waste Disposal
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Transcript Human Waste Disposal
Human Waste Disposal
More than 500 pathogenic bacteria,
viruses, and parasites can travel from
human or animal excrement through
water.
Natural Processes
In many areas, outdoor urination and
defecation is the norm.
○ When population densities are low, natural
processes can quickly eliminate waste.
Process for purification of and treatment of
municipal wastewater
Water is passed through a screen to remove
debris
A floccing agent, such as alum, is added in the
water
○ Flocculation process that combines small particles
into larger particles that become sediment
Suspended particles clump and settle out
Pathogenic organisms are killed by chlorination,
UV or ozone
Municipal Sewage Treatment
Primary Treatment - physical (mechanical)
separation of large solids from the waste
stream
Uses sticks, grit (stones), screens & filters =
sludge settles out
Removes 60% suspended solids & 30% organic
waste (ex. Bacteria)
Does NOT remove phosphaste, nitrate,
pesticides, salts, radioisotopes
Are not designed to remove pharmaceutical
chemicals from wastewater
Secondary Treatment biological degradation of
dissolved organic
compounds
Effluent from primary
treatment transferred into
trickling bed, or aeration tank
or to activated sludge
treatment
○ Aerobic bacteria filter out 90% of
biodegradable organic waste
Chlorine disinfection tank kills
bacteria & removes
discoloration
Ozone is an effective
alternative to chlorine
Sludge – is either
incinerated, put in land
fills, or used as
fertilizers
Cost
The cost per unit of pollutants removed
increases as the concentration of the
pollutant decreases
Removing smaller and smaller pollutants
require more processing and more
sophisticated removal techniques
Tertiary Treatment (advanced
treatment) – special chemical and
physical treatment that remove
specific pollutants after primary &
secondary treatment.
Chemicals, or natural wetlands.
Growing interest in membrane
technology – reverse osmosis,
ultrafiltration (too $$$)
Wastewater Gardens – artificial
wetland system used to treat small
amounts of sewage
Municipal Sewage Treatment
Areas of Progress
In 1998, EPA switched regulatory
approaches. Rather than issue standards
on a site by site approach, the focus is
now on watershed-level monitoring and
protection.
States are required to identify waters not
meeting water quality goals and develop total
maximum daily loads for each pollutant and
each listed water body.
WATER LEGISLATION
Clean Water Act (1972)
Goal was to return all US surface waters to
“fishable and swimmable” conditions.
○ For Point Sources, Discharge Permits and Best
Practicable Control Technology are required.
Set zero discharge for 126 priority toxic pollutants.
Clean Water Act (1972/1977)
Addressed regulations for point source
pollutants, non-point pollutants, & municipal
waste treatment plants
Areas of Contention
Draining or Filling of Wetlands
○ Many consider this taking of private land.
Un-funded Mandates
○ State or local governments must spend monies not
repaid by Congress.
Other Water Legislation
Safe Drinking Water Act (1974) – established max.
containment levels for pollutants
Great Lakes Water Quality Agreement (1972)
London Dumping Convention (1990)