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GREASE SEPARATORS AND TRAPS

Purpose

Grease separators are used to separate grease in wastewater from kitchens, meal preparation shops, meat workshops, and the like. Grease separation from wastewater reduced grease load (BOD5) of wastewater

Process

A gravity grease separator removes grease only with respect grease physical characteristic (less density than that of water) that are collected on wastewater surface, held back with a scumboard and then manually scummed off. When using flotation separation, grease drops presented inside whole wastewater volume flow through a separator and are “collected” with tiny air bubbles and then they are accumulated on water surface and mechanically skimmed off.

Legend:

1. Inflow, 2. Sedimentation zone, 3. Scumboard (baffling), 4. Flotation zone, 5. Aeration, 6. Grease skimming-off surface, 7. Grease entrapped zone, 8. Outflow

Design description

Grease gravity separators are plastic tanks provided with inside built-in equipment. Grease flotation separators are plastic/rust-resistant tanks with technological (mechanical) equipment Wastewater entering the treatment plant is stilled down and then flows through a scumboard to a next zone where floating grease is separated and collected on the water surface and manually scummed off. It suits for less wastewater volume flowing in with less grease content. In a flotation grease separator a special equipment (pump, and the like) saturates wastewater with air that is released in the stilling zone and which “collects” scattered grease drops and entrains them to water surface where they are cumulated, a part of treated water returns back to flotation section. Grease floated out to the surface is mechanically skimmed off and put in a bin. From where grease can be pumped out to an accumulation tank as far as to ca. 10 m away. Separated grease is collected and stored in a special container. It has to be disposed in special-purpose facilities – rendering plants, incinerating plants, and the like.

Advantages

Substance load reduction of wastewater. Grease removed from wastewater substantially reduces substance load of wastewater entering the treatment plant. It allows to reduce the size of treatment plant aeration tanks, has less demands on attendance, less production of excess sludge, etc. Grease content of wastewater passing through the separator is reduced by 60 up to 85 % with respect the separator type used. This high efficiency enables trouble-free wastewater treatment with the wastewater treatment plant and needs no additional technology to be applied.