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Unformatted text preview: results from
experimental tests.
Design of floating thickeners is based on the knowledge
of: • Wastewater flow rate and solid loading
• Airtosolid ratio (typically expressed as volume of
air/mass of solids or mass of air/mass of solids) • Overflow rate (or rise velocity of solids)
• Final solid loading in sludge
PIERO M. ARMENANTE
NJIT AirtoSolid Ratio (A/S Ratio)
• The A/S ratio is the amount of air that must be
generated in the wastewater to produce the desired
separation of the solids (expressed as volume of
air/mass of solids or mass of air/mass of solids) • The A/S ratio must be determined experimentally
from test runs • Once the A/S ratio is known it is possible to calculate
the pressure required to dissolve enough air in the
wastewater to produce the desired amount of air
during decompression • Typical A/S ratios are in the range 0.005  0.060 mL
air/mg solids (0.0065  0.08 mg air/mg solids) PIERO M. ARMENANTE
NJIT Nomenclature for Flotation
f = correction factor to account for nonsaturation
of water by air at pressure P
Fair = net mass flow rate of air available for
flotation (mg/h)
Fsolids = incoming mass flow rate of solids (mg/h)
P = pressure of pressurized wastewater (atm)
Po = pressure after depressurization (atm),
typically equal to the atmospheric pressure
Q...
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 Spring '99
 PieroM.Armenante
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