Grit Removal Essay

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A brief discussion of grit removal

Introduction
This report mainly discusses the grit, grit in the sewage treatment has been one of the key issues of concern. We discussed from the following points grit, what is grit? Why do we need to remove grit?As well as the facilities required for grit removal. We also discussed the advantages and disadvantages of these facilities during grit removal.Finally, we also talked about how the grit separated from the effluent will be used, and we will also discuss similar girt separation techniques.
Main body
What is grit?

Conventional grit removal equipment is designed based on the mistaken assumption that all grit particles are perfect spheres of silica sand greater than 212 microns in diameter and with …show more content…

• A relatively low putrescible organic content may be removed with a well controlled rate of aeration.
• Performance of downstream units may be improved by using pre-aeration to reduce septic conditions in incoming wastewater.
• Aerated grit chambers are versatile, allowing for chemical addition, mixing, preaeration, and flocculation.
Vortex-Type Grit Chamber
• These systems remove a high percentage of fine grit, up to 73 percent of 140-mesh (0.11 mm/0.004 in diameter) size.
• Vortex grit removal systems have a consistent removal efficiency over a wide flow range.
• There are no submerged bearings or parts that require maintenance.
• The “footprint” (horizontal dimension) of a vortex grit removal system is small relative to other grit removal systems, making it advantageous when space is an issue.
• Headloss through a vortex system is minimal, typically 6 mm (0.25 in). These systems are also energy efficient. Detritus Tank
Detritus tanks do not require flow control because all bearings and moving mechanical parts are above the water line. There is minimal headloss in this type of unit.
Horizontal Flow Grit …show more content…

Aerated grit chambers also require more power than other grit removal processes, and maintenance and control of the aeration system requires additional labor.
Vortex-Type Grit Chamber
• Vortex grit removal systems are usually of a proprietary design, which makes modifications difficult.
• Paddles tend to collect rags.
• Vortex units usually require deep excavation due to their depth, increasing construction costs, especially if unrippable rock is present.
• The grit sump tends to clog and requires high-pressure agitation using water or air to loosen grit compacted in the sump.
Detritus Tank
• Detritus tanks have difficulty achieving uniform flow distribution over a wide range of flows because the inlet baffles cannot be adjusted.
• This type of removal system removes large quantities of organic material, especially at low flows, and thus requires grit washing and classifying.
• Grit may be lost in shallow installations (less than 0.9 m [3 ft]) due to the agitation created by the rake arm associated with this system.
Horizontal Flow Grit Chamber
• It is difficult to maintain a 0.3 m/s (1 ft/s) velocity over a wide range of

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