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Degritter

PURPOSE

Degritter are used for eliminating gravel, sand, fiber and small mineral particles from primary water to prevent sediment formation in channels and pipelines and to protect pumps and other equipment from an abrasive effect.

TECHNOLOGICAL PROCESS DESCRIPTION

The working principle of degritters is based on the application of gravity forces. When waste water moves, every undissolved particle located in it moves horizontally together with a water jet (with the same speed as the jet) and simultaneously settles down under the influence of gravity load - with the speed corresponding to the size and relative density of the particle. Under the influence of gravity, a load of particles relative density of which is more than the relative density of water, drop to the bottom due to their movement together with water in reservoir.

Due to the turbulence of the water flow, vertical water movements appear in the degritter, directed upwards and downwards. Water flows directed upwards prevent residual settling down and provide a takedown of particles together with water.
Therefore the higher flow turbulence is, the larger particles will be taken out with water and vice versa - the slower flow speed it is, the smaller and lighter particles will settle out.

The water movement speed in the degritter shall be constant, independent of the waste water inflow variations. Constant speed is maintained by flat-topped water discharge unit, the change of aeration degree, the application of computer-aided inspection over the water level in inlet channels.

Degritters are designed for such a water movement speed when only the most serious mineral contaminants fall out and small organic particles do not do this.

Degritters cleaned from fallen out residual are performed in different ways. If waste water consumption supplied to station is negligible, degritters can be cleaned with a pump which evacuates sand with water. If the residual amount at the degritter bottom is impressive, it can be removed mechanically.

In direction of the water movement, degritters can be divided into the following types:

  • horizontal - when water moves horizontally with linear or circular water movement;
  • vertical - when water moves vertically upwards;
  • with spiral water movement (tangential and aerated).

Voronezh-Aqua experts are ready to sort out the optimum type of degritters in accordance with the client's requirements.

HORIZONTAL DEGRITTORS

PURPOSE

Degrittors are used for elimination of gravel, sand, fiber and small mineral particles from primary water to prevent sediment formation in channels and pipelines and to protect pumps and other equipment from abrasive effect.
TECHNOLOGICAL PROCESS DESCRIPTION

Horizontal degritters are reinforced concrete tanks with rectangular or trapezoidal cross-section where water moves at a low speed.

In horizontal degritters, waste water moves linearly or circularly. When waste water moves, every undissolved particle located in it moves downwards together with the water jet under the influence of gravity load with speed corresponding to size and relative density of the particle. The higher the water flow speed is, the higher the flow turbulence is and the larger particles will be taken out with water. The slower the flow is, the smaller and lighter particles will settle out.

In degritters, waste water undergoes two cleaning steps:

  • primary precipitation in the first chamber of degritter;
  • separation of suspended particles in the second chamber (it is possible to use a thin-layer module).

The chambers of the degritter are separated from each other with watering spot partition with screen holding floating particles.

The thin-layer module in the second chamber of the degritter is used for separation of floating particles of oil products which then are eliminated from the surface.

VERTICAL DEGRITTORS

PURPOSE

Degritter are used for the elimination of gravel, sand, fiber and small mineral particles from primary water to prevent sediment formation in channels and pipelines and to protect pumps and other equipment from the abrasive effect.

TECHNOLOGICAL PROCESS DESCRIPTION

A vertical degritter is a reinforced concrete vertical settler designed for holding waste water for 30–60 sec.

The working principle of the vertical degritter is that primary waste water containing sand is supplied to the central cylinder of the degritter where speed is partially lowered and water is calmed down. When the water moves from the central cylinder to the lower part of the degritter, the flow speed is reduced and sand grains begin settling. Water purified from sand through external hole clearance goes up to the overfall crown and runs down into the receiver.

Sand collected from the lower part of the detritor is eliminated and forwarded to sand platforms.

DEGRITTERS WITH SPIRAL WATER MOVEMENT

PURPOSE

Degritters are used for the elimination of gravel, sand, fiber and small mineral particles from primary water to prevent sediment formation in channels and pipelines and to protect pumps and other equipment from the abrasive effect.

TECHNOLOGICAL PROCESS DESCRIPTION

Tangential degritters have a cylindrical form. Water inlet is performed tangentially. This provides a spin motion of the flow. In these degritters every particle is subject to the influence of centrifugal and gravity forces. This furthers more intensive separation of sand from water and light organic impurities which, due to the spin motion, are maintained in suspended condition and do not settle out. Tangential degritters provide full holding of sand with small amount of organic contaminants. This technology gives an opportunity to settle down up to 90% of sand.

Waste water purified in a tangential degritters has pressure. It is suitable for arranging further equipment.

Aerated degritters are a development of tangential degritters. They are designed as extended reservoirs. The spin motion in them is created via waste water aeration. Aerators in this degritter are installed along one of the walls throughout the length of the degritter. Under the aerator there is a tray for collecting sand. Under the influence of aeration, waste water moves by spiral and particles fall out near the bottom section.

TECHNOLOGICAL PROCESS SCHEME

Features:
  • Operational safety and easy maintenance
  • High-quality materials
  • Long operation period