Grit Separators

Grit separators are systems designed to remove grits, trash, debris, sediment, and some amount of oil and grease from the influent water stream. These separators are specifically suited to capture particulates and hydrocarbons from small and highly impervious areas. They are best for small areas which produce heavy loads of sediment and hydrocarbons, such as parking lots, roads, gas stations and convenience stores. The grit separators operate on the principles of sedimentation. They are also known as oil separators.


Grit separators are very famous because they are comparatively cheaper and they can be easily installed at many small sites without sacrificing land. These separators consist of one or more chambers. These multi-chambered structures are designed to remove course sediment and oils. They don't provide any treatment of fine sediments and soluble pollutants. The separators have limited storage capacity and so they have very little impact on stream flow.

Besides creating blockage problems, grits are a constant source of wear & tear of the downstream units and equipment. There are different kinds of grit separation equipment to fulfill specific job requirements. They are optimally designed for the required hydraulics to ensure maximum grit separation even at peak hydraulic load. The grit withdrawal section is designed in such a way that it removes the settled grits without disturbing the settling in the main section. It lifts the water contents so that grit disposal does not pose excessive water spillage problem. The grit separators are usually cleaned by pumping out the contents of each chamber to a tanker trunk.


Working of Grit Separators
Grit separators are also known as gravity separators. They are hydrodynamic separation devices that are designed to remove grit and heavy sediments, etc from water through gravitational settling and trapping. These units contain a permanent pool of water. Typically they consist of an inlet chamber, separation or storage chamber, and an access port for maintenance purposes. The influent water enters the inlet chamber where heavy sediments and solids drop out. Subsequently the flow moves into the main gravity separation chamber, where suspended solids are settled further. The grease and oil are skimmed and stored in a waste oil storage compartment for future removal. The clarified runoff is discharged after moving in the outlet chamber.

Types of Grit Separators

• Square Grit Collectors: They are the most common used units because of its simplicity in design and its operational reliability. These units come either with Screw Classifier or with Rake Classifier.
  
  
• Rectangular Grit Collectors: These grit collectors are useful when the plant layout does not allow the square units or where there are certain process considerations. These units are usually provided with moving scrappers driven through the chain.
  
  
• Aerated Grit Channel: It is an efficient concept for optimal performance of any grit removal system. The grit separation is controlled by means of air circulation across the baffle.