Processes

MIL-HDBK-1005/9A

d) Polyelectrolytes. Organic polymers can be used for

breaking emulsions. A wide variety of polymers with varying

molecular weight, charge, and different monomers that can be used

for oily waste are available. Polymers such as polyamines,

quaternary amines, and polyacrylamates are effective for emulsion

breaking. The quaternary amine polymers and non-ionic polymers

can be applied over a wide range of pH conditions and are

compatible with processes for dissolved metals removal that employ

pH adjustment followed by removal of precipitates.

e) Chemical Mixing and Flocculation. A two-step

procedure is required for chemical addition to wastewater. The

first step is rapid mixing to provide a thorough and complete

dispersal of chemical throughout the oily waste. A short

detention times of less than 1 minute is usually adequate and in-

line or mechanical mixers can be used. The rapid mix stage is

followed by slow mixing or flocculation to form larger floc

particles. This is carried out in either a mechanically mixed

tank or a baffled tank. A detention time of 10 to 30 minutes

should be used for the formation of properly sized floc. The

mixing speed is to be kept low to avoid floc shear.

f) Floc Separation. Separation of the flocculated oil

and other solids from the water after chemical addition is the

most vital operation in the treatment of emulsified oily wastes.

Separation can be achieved in gravity settling, DAF or IAF.

Design guidelines and criteria for these unit processes are

presented in paragraphs 3.10.5 and 3.10.6.

3.10

Design Criteria for Oil-Water Separators and

Appurtenances

3.10.1

General

3.10.1.1 Processes. The basic process for removing oil from

wastewater is the gravity type oil-water separator. The extent to

which receiving waters or treatment works are impacted by

separator effluent determines whether additional treatment is

required. Treatment methods available for improving separator

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