Transcript Environmental Technology

Environmental Technology
Wastewater Management
Module 6.0
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
city’s water supply
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
Obj 6.1: Wastewater
“Strength”
 BOD
 TSS
 Nitrogen
 Phosphorus
 Pathogens
 Untreated
sewage
is about 99.9%
water and only
0.1% impurities
and solids
Wastewater “Strength”
Oxygen BOD
Demand: high
demand indicates
lots of organics and
micro-organisms
TSS
 Total Suspended
Solids: typically only
0.1% of total
sewage
 Biochemical
Wastewater “Strength”
 compounds
of
Nitrogen such as
ammonia, nitrites,
and nitrates
(~35mg/L)
 Phosphor
compounds such as
phosphates
(~10mg/L)
Nitrogen
Phosphorus
Wastewater “Strength”
 Protozoa,
bacteria,
and other disease
causing organisms
 E.coli indicative of
human waste
 detected by Coliform
test
Pathogens
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)
Obj 6.4: Storm vs Sanitary
Sewers?
Similarities
 both are converging systems
 both use pipes and manholes
 both use Manning’s Equation to
examine flow characteristics
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
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)