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GRIT CHAMBERS

ASHWANI KUMAR1NT12CV064

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GRITGrit is the heavy mineral material found in

raw sewage, and it may contain sand, gravel, silt, cinders, broken glass, small fragments of metal and other small inorganic solids.

Subsiding velocities or specific gravity substantially greater than those of organic putrescible solids in water.

Ex-eggshells, bone chips, sand, gravel, silt etc..

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GRIT CHAMBER Grit chamber is the second unit operation

used in primary treatment of wastewater and it is intended to remove suspended inorganic particles such as sandy and gritty matter from the wastewater

limited to municipal wastewaterGrit chambers are provided to protect

moving mechanical equipment from abrasion and abnormal wear; avoid deposition in pipelines, channel, and conduits; and to reduce frequency of digester cleaning

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TYPES OF GRIT CHAMBERSHorizontal Flow Grit ChamberAerated Grit Chamber

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HORIZONTAL FLOW GRIT CHAMBER

Velocity maintained is 0.3 m/sPermit the heavier grit to settle but carry

organic particlesTo maintain a constant velocity of flow, a

control section is placed at the end of the channel.

A control section varies with the c/s area of the flow in the section in direct proportion to the flow.

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Fig: Horizontal Flow Grit Chamber

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DESIGN OF GRIT CHAMBERSSettling velocityOverflow rateDetention periodBottom scourVelocity control devicesNumber of unitsDimensions of each unit

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AERATED GRIT CHAMBERIt consists of a standard spiral flow aeration

tank provided with air diffusion tubes placed on one side of the tank.

Grit particles tend to settle down to the bottom of the tank at rates dependant upon the particle size and the bottom velocity of roll of the spiral flow, which depends on the rate of air diffusion through diffuser tubes and shape of aeration tank.

The lighter organic particles are carried with roll of the spiral motion

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Fig:Aerated grit chamber

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DISPOSAL OF GRITClean grit is characterized by the lack of

odourIt is included when detention time is more or

flow through velocity is lessDisposed by dumping or burying or by

sanitary landfillUnwashed grit acts a soil conditioner and will

give good yeild

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