Title: Wastewater
1Wastewater Its Journey to Treatment and Return
to the Environment
- ESI
- BY-Sanni Kumar Sinha
- B.Tech(c.s.) 1st year
2Where does it all go!
Where does the water from the washer go?
By gravity flow, the waste is on its way to your
local wastewater treatment plant!
3Why treat wastewater?
- Causes a demand for dissolved oxygen (lower DO
levels of streams) - Adds nutrients (nitrate and phosphate) to cause
excessive growth - Increases suspended solids or sediments in
streams (turbidity increase)
4Parkway WWTP
Sewagesheds
- an area where sewage is collected and delivered
to a WWPT
Bowie WWTP
Western Branch WWTP
Blue Plains WWTP
Marlboro Meadows WWTP
Piscataway WWTP
Mattawoman WWTP
approximate boundaries
5Where do you locate the WWTP in the watershed?
Consider the four possible sites.
6The volume of wastewater
PGC 1992 Comprehensive Ten Year Water and
Sewerage Plan
7Levels of Treatment
- Primary
- removal by physical separation of grit and large
objects (material to landfill for disposal) - Secondary
- aerobic microbiological process (sludge)
- organic matter O2 ? CO2 NH3 H2O
- NH3 ? NO3-
- lowers suspended solids content (into sludge)
Mostly dead microbes
aquatic nutrient
8Secondary process
To tertiary process
From primary process
Settling collects sludge on bottom
Aeration and rapid mixing
air diffuser
9Levels of Treatment continued
- Tertiary (advanced)
- anaerobic microbiological process with a
different microbe where O2 is toxic (more sludge) - NO3- ? N2 (escapes to atmosphere)
- PO4-3 if not removed in sludge in secondary
process - PO4-3 Al3 ? AlPO4 (s) (into sludge)
- - aeration to strip N2 and re-oxygenate (add DO)
10Tertiary process
From secondary process
add methanol as food source
Effluent
Settling collects sludge on bottom
Slow mixing to keep suspended and O2 out
11When the treatment is done
- Effluent back to stream after
- a final carbon filtration and
- chlorination/dechlorination
- Sludge very nutrient rich
- applied directly to land as fertilizer
- incinerated (good fuel after drying)
- composted (Compro from WSSC)
Note Leafgro is composted leaves and grass
from MES