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Removal of Oil and Grease (Hydrocarbons)

Q. How can oil and grease be removed?

A. The method of removal depends on whether they are present in free or emulsified form and on their concentration

Q. How do free and emulsified oil differ from each other?
A. free oil consists of large droplets (> 20 micron in size) whereas emulsified oil consists of very small droplets (<20 micron in size)

Q. How can I tell if the oil and grease are present in free or emulsified form?
A. If they are in free form, you’ll see the oil floating on the surface of the water or you will see a “sheen” to the water.

Q. How can I know the concentration in my water?
A. A water laboratory can test a sample of your water.

Q. If oil can be seen floating on the surface of the water and a laboratory test shows a concentration greater than 70 mg/l, how can the oil be removed?
A. The most common methods are an oil water separator and an oil skimmer.

Q. If oil cannot be seen in the water, what are the methods to remove it?
A. If oil concentration is >70 mg/l, the emulsion must be broken and the resulting free oil is removed by an oil water separator or an oil skimmer.Types of Filters and How They Work

If oil concentration is < 70 mg/l, the oil can be removed by using a clay filter. The granules of clay act as a magnet, drawing the oil molecules out of the water and causing them to attach to the surfaces of the clay. The clay filter will remove > 90 percent of the oil. If further removal is required, a granular activated carbon filter will be effective.

To design a filter system that will be effective in treating your waste water, contact an Everfilt Applications Engineer at (951) 360-8380 or at everfilt@everfilt.com.