Oil water separation usually constitutes a pre-treatment unit process for wastewaters containing oil. The oil can be in either free or emulsified forms. Dedicated devices and equipment are employed for removal of free oils and emulsified oils. The separated oil is skimmed off for collection and further disposal or treatment, which again require dedicated equipment for the purpose.

Types of Products

¤ API Oil Water Separator
The main function of an API Oil Water Separator is to separate the free oil from the wastewaters primarily refinery wastewaters. The free oil has size of over 150 microns, is usually defined as oil globules. There are a number of factors at which the ability of a separator to remove free oil depends. It includes the type and state of the oil in the waste flow, the characteristics of the carrier stream and the design and size of the unit. The principle of separation is based on gravity separation wherein the oil, being lighter than water, floats to the surface on providing quiescent conditions. The API separator tank consists of two basic sections: One is the inlet section and the other is oil water separator channel. Both of them performs particular functions.


Inlet Section
The inlet section consists of the pre-separator flume and the forebay sections.

• Pre-separator Flume
  The pre separator flume performs two main functions: reduction of flow velocity and collection of floating oil. The effluent end of the pre-separator section consists of three pieces of equipment. A bar screen or trash rack, an oil skimmer and an oil retention baffle in that order. We supply each of these equipment. Kindly refer to the oil skimmer section for different types of oil skimmers.
  
  
• Separator Forebay
  This part of the separator acts It acts as a header which distributes the influent to the separator channels. For removal of any oil trapped oil skimmer may also be provided in this section. Refer to the oil skimmer section for various types of oil skimmers supplied by Triveni.

Separator Section
Usually the separator section employs the following equipment in the order.

• Velocity Head Diffusion Devices
  They help to reduce flow turbulence and distribute the flow evenly over the channel cross-sectional area. They are provided either in vertical slot baffle type or in reaction jet baffle type. Triveni supplies each of these equipment.
  
  
• Oil & Sludge Moving Device
  Triveni supplies chain & scraper type mechanism for the purpose. The equipment consists of two parallel strands of chain, one along each longitudinal wall, moving over motor driven sprockets and crossing the entire length of the tank. The chains are provided with fledges at regular spacing and extending across the width of the channel. As the flights travel downstream, separated oil is moved towards an oil skimmer located at the downstream end of the tank. On the return trip, the flights move along the channel floor pushing sludge towards the sludge collecting hoppers or trough at the influent end.

The sprockets and chains are provided in cast steel or stainless steel or non-metallic construction depending on the client's need. The flights are provided in wood or FRP construction. The internals of the tank, such as shafts, track angles, support brackets etc. can be in either steel or stainless steel construction.

¤ Dissolved Air Flotation
Dissolved Air Flotation systems are used for the removal of suspended solids and emulsified oil from liquids.

Inorder to remove the emulsified oil, the chemicals are added to break the emulsions. For this purpose additional flash mixer and flocculation units are provided upstream of Dissolved Air Flotation tank.

Millions of microscopic bubbles are introduced into the process water to accomplish the flotation of solids. It is achieved by drawing a portion of the effluent from the downstream end of the DAF tank and then pumping the recycled effluent and atmospheric air to a suitable pressure retention tank / saturation vessel.

The recycled effluent gets saturated here at elevated pressure in the pressure tank. The air saturated stream is then blended with raw wastewater in the DAF tank. As the pressurized flow is restored to atmospheric pressure in the DAF tank, millions of microscopic bubbles are released which attach themselves to the suspended particles in the flow and lift the particles to the surface for effective removal.

¤ Skimmer
Our company provides a large range of oil skimming equipment for rectangular and circular tank configurations. They suit all conditions of skimming in both manual and automatic operating units. We offer six basic types of skimming equipment. Each type is manufactured in different styles to assure the widest choice to meet all operating condition.

Roto-Skim
Roto skim is the simplest and most economical skimming equipment, that is largely used in municipal and industrial wastewater installations. It is made of a slotted steel pipe that is installed with the edge slightly above the liquid surface. When the edge is rotated below the surface the floatable solids and some liquid flow into the pipe openings and are exhaled of the tank for disposal. The Roto-Skim is available in four basic types: lever, rack & pinion, worm gear and motor operated.



Scraper type Power Skimmer
Scraper type power skimmers are used with a conventional four shaft sludge collector. They conveys the skimmings from liquid level, up a dewatering beach and discharges into a trough properly slopped or equipped with a screw conveyor. At those places where separate skimming and sludge scraping are required, rigid and pivoted flight full length skimmers are used. They are mainly consist of pivoted flights at regular spacing along two strands of chain



Spiral Skimmer
Spiral skimmers are mainly used for light frothy scums. They are power operated made of revolving spiral shaped blade, mounted ahead of a scum trough, skims the floating materials from the tank surface. Then they deposit it into the scum trough for further disposal.


Circular Skimmer
Circular skimmers are used where small volumes of skimmings are required. Its common applications include primary clarifiers in sewage or industrial wastewater treatment plants, where only small amounts of oils must be skimmed.

Roll Skimmer
Roll skimmers are widely applied in the refining, petro-chemcial, automotive, steel mill, machine shop and other similar industries. They are used for free mineral oil removal from liquid surfaces. The skimming comprising of a pipe roll revolves down into an oil film on the water surfaces and preferentially picks up an oil film on the roll surface. The adhering oil film is doctored off into a trough for further removal. They can be provided either as wall mounted fixed units or pontoon mounted floating units.

Belt Skimmer
Belt skimmers are similar in operation and application to the roll skimmers except that instead of a roll a belt is used. One of its important advantage is that it combines oil skimming and lifting of the skimmed oil to a higher point in one operation.

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