TM 5-4610-218-12
dissolved gases. Adjust the raw water flow as de-
slurry, and solution concentration,
scribed in paragraph 2-8.
and flow rate. Curves are based on the
solution and slurry concentration ex-
e. Slurry Blanket Rotation. The slurry blan-
pressed in pounds of chemical per gal-
ket in the erdlator must be kept rotating, Banking
lon of water as follows;
the slurry blanket on the outer circumference indi-
cates too much rotation while insufficient rotation
Ferric chloride. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1/2
is indicated by a lack of slurry blanket rotation
Calcium hypoclorite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1/8
around and near the outer circumference. The rota-
Limesstone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
tion of the slurry blanket is controlled by the speed
Diatomaccous earth . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1/2
of the agitator drive belt. Refer to figure 2-14 and
Carton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 1/4
adjust the agitator drive belt as necessary.
NOTE
NOTE
The slurry blanket, sometimes called
floe, in the jellylike curd formed fol-
lowing the addition of the limestone
slurry and the ferric chloride solution
to the raw water as the water is agi-
tated. The jelly- like floc first appears
as small particles which grow by ad-
herence with other particles. As the
(The curve for carbon is on the same chart as for
water swirls, the small particles joint
limestone and each curve is identified).
with others to enmesh most of the sus-
pended bacteria, dirt, and organic
c. Recharging Chemical Equipment.
matter to form a visible slurry blan-
(1) Chemical slurry feeder. When the level
ket.
of the limestone or diatomaceous earth slurry
f. Slurry Level Control and Sludge Re-
reaches the low level marker, recharge the slurry
moval. After several hours of continuous oper-
compartments in a manner similar to that described
ation, the amount of slurry in the erdlator tank will
in para 2-8 and 2-9. The required amount of lime-
increase until the slurry blanket reaches the slurry
stone for recharge is 14 pounds (6.353 kg). The re-
drawoff port. The slurry will then overflow into the
quired amount of diatomaceous earth for recharge
slurry weir box and into the sludge concentrator
is 7 pounds (3.177 kg).
tank. The slurry blanket will rise in the sludge con-
(2) Chemical solution feeder. When the
centrator tank until it reaches the top of the inner
level of ferric chloride or calcium hypochlorite solu-
tank. The concentrator tank control valves CV - 16
tions are within 4-1/2 inches (11.43 cm) of the bot-
and CV-17 are kept open during normal operation.
tom of the solution tanks, recharge the tank re-
Also, the concentrator tank drain valve DV-21 is
quiring additional solution as described in para 2-8.
partially open. As the slurry flows into the concen-
d. Preaeration Control. The aspirator aeration
trator tank, the clear water overflows into the inner
manifold, located above the erdlator tank, provides
tank and into the wet weil. A portion of the slurry is
preaeration of the raw water coming into the influ-
drained to waste. The amount of slurry flow from
ent launder. The manifold control valves CV-10 and
the erdlator tank to the sludge concentrator tank
CV-11 normally are open.
equals the flow of water through the control valve
CV-17 into the wet well tank and the flow of sludge
(1) The normal reading of the pressure gage
through the drain valve DV-21.
PG-1 with both valves open is 5 to 7 psi. If the pres-
sure ripes above this reading, it indicates that the
NOTE
aspirators are clogged or valves are closed. To rem-
If the flow of water drawn into the wet
edy this condition, open the valves or remove the
well tank or the amount of sludge
foreign matter.
drained to waste is too great, it will
(2) If numerous air bubbles are observed on
cause turbulence in the sludge con-
the surface of the water in the erdlator tank, this
centrator tank and cause slurry carry-
indicates that the water is supersaturated with dis-
over to the wet well tank.
solved gases. Partially close or completely close one
or both of the control valves, This corrective action
(1) Do not permit the slurry blanket in the
sludge concentrator tank to rise above or below the
will increase the pressure and aeration and release
Change 3
2-49
