MIL-HDBK-1005/9A
c) Sludge Production. Sludge production and
disposal, and scaling must be considered in design of
neutralization systems.
(1) Waste solutions with no suspended solids or
dissolved solids at less than saturation concentration produce
negligible sludge upon neutralization.
(2) Waste solutions with or without suspended
solids, but saturated dissolved solids (such as CaSO4)
in the neutralized mixture, create sludge handling and
significant scaling problems.
d) Treatment Process Alternatives. The following
treatment alternatives should be considered for neutralization.
or pellets, quicklime (CaO), or hydrated lime (Ca(OH)2).
(2) Limestone beds. Use upflow or downflow
systems. Limit acid concentration to 0.3 to 0.6 percent to
minimize bed coating with calcium sulfate. Use recirculation to
reduce required bed depth. Load at less than 1 gpm/square ft
(40 L/min/square m) for downflow beds. Higher rates may be used
for upflow beds since solids and precipitate are carried out.
(3) Chemical Mixing. If mixing is required,
provide 200 to 400 horsepower per million gallons of tank's
capacity (mechanical-type mixer). Check pumping or turnover
rate of mixing equipment.
(4) Acid neutralization. Use sulfuric or
hydrochloric acid for strong acid neutralization of alkaline
wastes. Use carbon dioxide, sodium bicarbonate, or fuel
combustion gas for weak acid neutralization and final adjustment
of pH.
(5) Process Staging. Provide at least two
separate stages for dampening pH fluctuations in continuous flow
systems. Additional stages are required for strong acid and
alkaline wastes and for fine tuning pH to desired effluent
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