what is grease interceptos

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What is grease trap?
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grease trap

• A grease trap also known as grease
  interceptor, grease recovery device and grease
  converter.
• It is a plumbing device (a type of trap) designed
  to intercept most greases and solids before they
  enter a wastewater disposal system. Common
  wastewater contains small amounts of oils which
  enter into septic tanks and treatment facilities
  to form a floating scum layer. This scum layer is
  very slowly digested and broken down by
  microorganisms in the anaerobic
  digestion process. Large amounts of oil from food
  preparation in restaurants can overwhelm a septic
  tank or treatment facility, causing release of
  untreated sewage into the environment.
  High-viscosity fats and cooking grease such
  as lard solidify when cooled, and can combine
  with other disposed solids to block drain pipes.

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Uses

• Restaurant and foodservice kitchens produce much
  waste grease which is present in the drain lines
  from various sinks, dishwashers and cooking
  equipment such as combi ovens and
  commercial woks. If not removed, the grease can
  clump and cause blockage and back-up in
  the sewer.
• In the US, sewers back up annually an estimated
  400,000 times, and municipal sewer overflows on
  40,000 occasions. The EPA has determined that
  sewer pipe blockages are the leading cause of
  sewer overflows, and grease is the primary cause
  of sewer blockages.2 Even if accumulated FOG
  does not escalate into blockages and sanitary
  sewer overflows, it can disrupt wastewater
  utility operations and increase operations and
  maintenance requirements .
• For these reasons, depending on the country,
  nearly all municipalities require commercial
  kitchen operations to use some type of
  interceptor device to collect grease before it
  enters sewers. Where FOG is a concern in the
  local wastewater system, communities have
  established inspection programs to ensure that
  these grease traps and/or interceptors are being
  routinely maintained.
• It is estimated 50 of all sewer overflows are
  caused by grease blockages, with over 10 billion
  US gallons (3.81010 l 8.3109 imp gal) of raw
  sewage spills annually.

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Method of operation

• When the outflow from the kitchen sink enters the
  grease trap, the solid food particles sink to the
  bottom, while lighter grease and oil floats to
  the top. The relatively grease-free water is then
  fed into the normal septic system. The food
  solids at the bottom and floating oil and grease
  must be periodically removed in a manner similar
  to septic tank pumping. A traditional grease trap
  is not a food disposal unit. Unfinished food must
  be scraped into the garbage or food recycling
  bin. Milkshakes, gravy, sauces and food solids
  must be scraped off dishes before entering the
  sink or dishwasher.

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• To maintain some degree of efficiency, there has
  been a trend to specify larger traps.
  Unfortunately, providing a large tank for
  the effluent to stand also means that food waste
  has time to settle to the bottom of the tank,
  reducing available volume and adding to clean-out
  problems. Also, rotting food contained within an
  interceptor breaks down, producing toxic waste
  (such as sulfur gases) - hydrogen
  sulfide combines with the water present to
  create sulfuric acid. This attacks mild steel and
  concrete materials, resulting in "rot out", On
  the other hand, polyethylene has acid-resisting
  properties. A bigger interceptor is not a better
  interceptor. In most cases, multiple interceptors
  in series will separate grease much better.
• Because it has been in the trap for some time,
  grease thus collected will be contaminated and is
  unsuitable for further use. This type of grease
  is called brown grease.

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Types

• There are three primary types of devices. The
  most common are the types specified
  by ASME (American Society Of Mechanical
  Engineers), utilizing baffles, or a proprietary
  inlet diffuser.
• Grease trap sizing is based on the size of the 2-
  or 3-compartment sink, dishwasher, pot sinks, and
  mop sinks. The cumulative flow rates of these
  devices, as well as overall grease retention
  capacity (in pounds or kilograms) are considered.
  Currently, ASME Standard (ASME A112.14.3) is
  being adopted by both of the National Model
  Plumbing Codes that cover most of the US. This
  standard requires that grease interceptors remove
  a minimum of 90 of incoming FOGS (fats, oils and
  greases). It also requires that grease
  interceptors are third-party tested and certified
  to 90 days compliance with the standard pumping.
  This third-party testing must be conducted by a
  recognized and approved third-party testing
  laboratory.

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• The most common passive grease traps are smaller,
  point-of-use units used under three-compartment
  sinks or adjacent to dishwashers in the kitchen.
• The second most common type of interceptor is the
  large in-ground tank, which is usually 5002,000
  US gallons (1,9007,600 l 4201,670 imp gal).
  These units are constructed of concrete, fiberglas
  s, or steel. By nature of their larger size, they
  have larger grease and solid storage capacities
  for high-flow applications such as
  a restaurant or hospital store. They are commonly
  called gravity interceptors. Interceptors require
  a retention time of 30 minutes to allow the fats,
  oils, grease and food solids to settle in the
  tank. As more waste water enters the tank, the
  grease-free water is pushed out of the tank. The
  rotting brown grease inside a grease trap or
  grease interceptor must be pumped out on a
  scheduled basis. The brown grease is not recycled
  and goes to landfill. On average 300 to 400
  pounds (140 to 180 kg) of brown grease goes to
  landfill annually from each restaurant.

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• A third system type, GRDs (grease recovery
  devices), removes the grease automatically when
  trapped. The recovered grease or "yellow grease"
  is recycled with the waste vegetable oil from the
  kitchen's deep-fryers. Restaurants must not pay
  for grease trap pumping as do restaurants with
  conventional grease traps or grease interceptors.
• Passive grease traps and passive grease
  interceptors must be emptied and cleaned when 25
  full. As the passive devices fill with fats,
  oils, and grease, they become less productive for
  grease recovery. A full grease trap does not stop
  any FOG from entering the sanitary sewer system.
  The emptied contents or "brown grease" is
  considered hazardous waste in many jurisdictions.
  "Brown grease" is generally not recycled and goes
  to landfill waste.