Environmental Engineering Reference
In-Depth Information
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Sludge withdrawal line plugged
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Return of well-nitrified waste activated sludge
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Too few tanks in service
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Damaged or missing baffles•
6.4.3 Causal factors for septic Wastewater or sludge
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Hydraulic
overload
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Overpumping of sludge
•
Collection system problems
•
Decreased influent solids loading
6.4.4 Causal factors for Too low Primary
sludge solids Concentrations
•
Hydraulic overload
•
Overpumping of sludge
•
Collection system problem
•
Decreased influent solids loading
6.4.5 Causal factors for Too high Primary
sludge solids Concentrations
•
Excessive grit and compacted material
•
Primary sludge pump malfunction
•
Sludge withdrawal line plugged
•
Sludge retention time too long
•
Increased influent loadings
6.5 effluenT froM seTTling TanKs
Upon completion of screening, degritting, and settling in sedimen-
tation basins, large debris, grit, and many settleable materials have
been removed from the wastestream. What is left is referred to as
pri-
mary effluent.
. Usually cloudy and frequently gray in color, primary efflu-
ent still contains large amounts of dissolved food and other chemicals
(nutrients). These nutrients are treated in the next step in the treatment
process (secondary treatment), which is discussed in the next chapter.
Note:
Two of the most important nutrients left to remove are phospho-
rus and ammonia. Although we want to remove these two nutrients from
the wastestream, we do not want to remove too much. Carbonaceous
microorganisms in secondary treatment (biological treatment) require
both phosphorus and ammonia.
