A good grit washing system is characterised by its ability to wash out the organic substances in the grit so that the loss on ignition in the washed grit is < 3%. In addition to the effective separation of organic and mineral components, the retention of fine sands is also decisive in practice, which is taken into account in the design of HUBER Grit Washing Plants.
Grit classifying and grit washing in a single and compact unit
- Lower disposal costs and volumes
- Utilisation of the Coanda effect ensures superior grit removal efficiency.
- Less than 3 % organic content
- High throughput capacity
- Proven Technology with more than 2,000 installations worldwide
The HUBER Coanda Grit Washing Plant RoSF4 offers exceptional grit management with advanced features, ensuring reliable, efficient, and environmentally friendly operation.
The HUBER Coanda Grit Washer RoSF4 integrates both grit classifying and grit washing into a single, compact unit. By utilizing the Coanda effect, the system ensures consistently high separation efficiency and excellent washing performance. This combined process effectively removes organic material from the grit, producing a cleaner, higher-quality residue while minimizing the need for separate processing steps.
HUBER Coanda Grit Washer RoSF4
Reliable reduction of the organic content of the grit to < 3%
Innovative technology: HUBER Coanda Grit Washer RoSF4 size III with frost protection for outdoor installation
Washed grit removed at a wastewater treatment plant
The loss on ignition of the washed grit is less than 3%
The HUBER Grit Washing Plant RoSF4 - high separation performance and best organic removal
Design and Function
Classifying with the Coanda Effect
A mixture of grit, organics, and water is introduced into a vortex chamber, where rotational movement is generated. This spinning action causes the mixture to flow downward through the trumpet-shaped Coanda Tulip, where the Coanda effect facilitates efficient separation of the free organic material from the heavier grit. The result is a cleaner, more effectively classified grit, ready for further dewatering or disposal.
The flow is directed along the curved inner surface of the Coanda Tulip by the Coanda effect, where the liquid adheres to the contour of the curved surface. This smooth diversion occurs without the generation of turbulent eddies, as the flow transitions from a fast rotating vertical direction to a gradually slower rotating horizontal direction. As a result, there is a high flow velocity along the inner surface of the Coanda Tulip, a moderate radial velocity just below the water surface, and a high velocity again at the weir, ensuring efficient separation of the grit from the organic matter.
The solids in the flow, including grit particles and organic material, are separated as a result of the flow diversion and reduction in flow velocity. This process, which depends on the settling velocity of the particles, causes the solids to sink to the bottom of the tank. The optimized flow pattern in the HUBER Coanda Grit Washer RoSF4 ensures that more than 95% of the grit particles in the range of 200 micron are efficiently separated, resulting in highly effective grit washing and classification.
Fluidised bed for outstanding grit washing
The separated grit is then subjected to a washing process, where organics attached to the grit particles are removed. This occurs in the bottom section of the HUBER Coanda Grit Washer RoSF4, where a fluidized grit bed is created. Wash water is introduced into a bottom chamber, which is separated from the main grit washer tank by a perforated plate and a perforated rubber diaphragm. The wash water flows upward through the diaphragm, distributing evenly across the bottom of the tank and generating the fluidized grit bed.
Within this bed, the grit particles rub against each other, effectively scrubbing off attached organic material. This washing process is enhanced by a central stirrer that keeps the particles in motion, ensuring continuous agitation and maximizing the removal of organic contaminants from the grit. The result is clean, thoroughly washed grit with a minimal amount of organic material attached, ready for further processing or disposal.
After the organic material has been effectively removed, the clean grit is transported through a classifying screw, where it is statically dewatered and then discharged into a container for disposal.
The organic material that remains in the HUBER Coanda Grit Washer RoSF4 is removed automatically, but in an intermittent process, depending on the overall flow and operational conditions. This ensures that the plant maintains a defined separation capacity, optimizing the performance of the system while maintaining consistent operation.
The continuous separation of grit from organics, along with its effective washing and dewatering, guarantees that the system operates efficiently, with minimal maintenance required and a high-quality end product that meets industry standards for grit disposal and environmental protection.
The Benefits of the HUBER Coanda Grit Washing Plant RoSF4
- No additional preceding screening required (e.g. < 6 mm)
- High grit and gravel yield optimized for maximum recovery
- Versatile Applications suitable for treatment of grit from sewers, gully waste, road sweepings
- No crushing of stones and gravel inside the plant
- The screw is supported on both ends for minimized wear
- Optional continuous operation features on-line grit level measurement, enabling uninterrupted grit removal even during feeding
- Encapsulated, odor-free plant
- Separate organics discharge allows for independent treatment of organics
- High throughput with up to 3 tons per hour
- Large diameter screws for a high solids throughput
- Durable construction with stainless steel stirrer and screw
- Proven performance with more than 2,000 installations worldwide give proof of customer satisfaction
- Easy integration designed for seamless incorporation into comprehensive treatment systems
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FAQ
Frequently Asked Questions
In order to be landfilled, the grit must be further treated before. Depending on the size of the sewage treatment plant and the amount of grit, grit classifiers or grit washers are used. The state of the art is now the grit washer.
Due to the additional washing, the organic content in the discharged grit can be guaranteed below 3%. This leads to possible lower disposal costs and volumes.
Both the grit washer and the grit classifier are fed with a grit-water mix. In the machine, the grit is separated from the water.
In contrast to the grit classifier, the grit washer is able to wash the separated grit. This means that the separated grit is freed from organic components as far as possible. The grit washer thus produces grit that is almost free of organic matter, whereas the separated grit in the grit classifier may contain a considerable amount of organic matter.
In municipal wastewater treatment, grit is separated in a grit trap. This separation takes place by sedimentation, i.e. the grit settles in the grit chamber after sufficient retention time. However, since there are not only mineral substances such as grit in the wastewater, but also many organic solids, these also settle to a greater or lesser extent. As a result, when the grit is discharged from the grit chamber, it sometimes contains a large amount of organic solids. This contamination of the grit with organic matter hinders, among other things, cost-effective landfilling or reuse of the grit.
Grit washing with a HUBER Grit Washer RoSF4 solves this problem and produces clean grit with an organic content of less than 3% loss on ignition, the HUBER Grit Washer RoSF G4E reduces the organic content to ≤ 5%.
