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Plant brochure designed by Charles L.
Woodruff 1999 and revised in June 2004.
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Kruger Oxidation Ditch Aeration Rotors
Maxi-rotors are used for aeration in the
Kruger Oxidation Ditches.
Aeration of the mixed liquor in the
oxidation ditch can be provided in a number of ways. The most common method
is to intensely agitate the surface of the liquid, which is open to the
atmosphere, with a large brush aerator (rotor). There are many variations in
the type of equipment available; however, all aeration systems have the
common purpose of vigorously mixing an oxygen-containing gas with the mixed
liquor. The biological oxidation process by horizontal rotor aeration works
through the mixed flow principle. A rapid turbulence of the ditch contents
mixes influent with air. It is simple, inexpensive, and efficient.
The Princeton Kruger Ditches contain 4
rotors in the circulating-type water channel at level surface which
generates circulating currents in the channel, supplies oxygen to the micro
organisms in the water, and treats wastewater biologically.
The agitating rotors supply a greater amount of oxygen to the liquor than
would be supplied by a bubbling aeration system, thus minimizing the power
requirement for oxygen supply and overall running cost. For an oxidation
ditch or alternate system to function satisfactorily, the velocity gradients
and dissolved oxygen throughout the entire area of the ditch or channel
should be relatively constant.
The rotor is mounted on a revolving horizontal shaft that is partly
submerged in the wastewater for oxygenation and circulation of the ditch
contents. |
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Kruger SCADA System View
Showing Location of The Rotors |
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Kruger SCADA System View
Showing Rotor Control |
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| Oxic conditions are
maintained by the rotor surface aerators. In the presence of dissolved
oxygen, the micro organisms convert stored BOD (biochemical oxygen demand)
to CO2, water, and increased cell mass. Biological nitrification occurs,
producing nitrite in an intermediate step and ultimately producing nitrate.
Following nitrification, nitrogen can be removed from the wastewater by
reducing the nitrate to nitrogen gas (N2), which is released to the
atmosphere. This process is commonly referred to as denitrification.
Denitrification requires anoxic conditions, as well as an organic carbon
source, to proceed. A probe
monitors the Dissolved Oxygen concentration in the mixed liquor and
transmits a signal to the control panel, which controls the operation of the
rotors via a custom programmed PLC.
While the Brush Rotors maintain oxic
conditions within the mixed liquor during the nitrification phases of the
process, the rotor bridge eliminates noise and aerosols, while providing
access for equipment maintenance. Discharging weirs controls the submergence
of the rotors. |
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The Maxi-Rotor |
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Maxi-Rotor Illustration |
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| The Maxi-Rotor is able to
provide in excess of 9.0Kg dissolved oxygen per hour per metre of rotor
length. The Maxi-Rotor is a rugged construction, vigorous turbulence
rotor. It has a diameter of 1,000mm and is manufactured in a range of
standard lengths. A major
advantage associated with horizontal rotors is that full maintenance access
is available to all components from bridge level without the need to
interfere with tank contents. |
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