Twin sludge degritting systems at two Illinois wastewater treatment plants are still running strong 22 years after installation. …
Hydro International's HeadCell® or Grit King® grit separation systems are the first stage of the grit removal process. These separation systems send concentrated grit and organics underflow to a SlurryCup™, TeaCup®, or OpTeaCup™ for grit washing. Washed grit is then sent to a Grit Snail® which is a quiescent grit dewatering belt escalator that captures, dewaters, and retains even the finest grit. Grit Snail® effectively removes the water to provide solids output with low water content which reduces solids handling and landfill costs.
The belt operates within an abrasion-resistant belt housing and incorporates components with no metal-to-metal contact reducing wear. The variable frequency drive adjusts belt speed to match changing grit loads and the torque-limiting clutch protects the drive system and belt from mechanical overload.
Municipal wastewater plants with combined sewers or industrial loads require greater dewatering capacity; different sizes of Grit Snail® units or multiple Grit Snail® units can be configured to match any grit load.
Only Grit Snail®
- Separates the grit washing and dewatering process to reduce turbulence
- Uses quiescent dewatering in order to retain even the finest grit particles
- Has the capacity to handle very high grit loading conditions
- Non-turbulent dewatering for clean, fine grit output from Hydro International's Advanced Grit Separation and Washing systems
Retain more, finer grit
Many conventional grit removal systems will combine washing and dewatering into a single process. Washing is a turbulent process, however, and dewatering should be performed under still conditions; combing these processes is why many types of systems fail to retain fine grit. Agitation from a combined washing / dewatering process can churn up finer grit allowing it to escape with water exiting the system. The Grit Snail® is a quiescent system with a slow-moving belt that eliminates this kind of turbulence, meaning that it retains more, finer particles.
Reduce operating costs
When matched with Hydro International separation and / or washing systems such as the HeadCell®, Grit King®, SlurryCup™, OpTeaCup® or TeaCup®, the Grit Snail® retains fine grit and outputs cleaned material with very low volatile solids or residual moisture, cutting odor and making the output easier to handle and dispose of. Your treatment plant is the best way to treat water and organics - avoid paying the expense of landfilling water and organic content with Grit Snail® dewatering.
Grit and fine abrasives are discharged by a grit washing unit into the Grit Snail® clarifier, where they settle onto the slow-moving stepped cleats.
The captured solids are gently lifted out of the clarifier at between 1 - 5 feet per minute (0.3 - 1.5 m/min).
Degritted water flows out of the clarifier via an overflow weir.
Dewatering begins as the grit and fine abrasives are quiescently raised from the clarifier pool which retains fine grit.
The dewatered abrasives are carried to the top of the Grit Snail®, where they are discharged into a disposal container for landfilling.
The slow-moving cleated belt gently escalates the grit from the clarifier, retaining fine grit, unlike turbulent dewatering systems which reintroduce captured grit back into the plant. The Grit Snail® is designed for durability and ease of maintenance, resulting in a very long product life and trouble-free operation.
- Removes 95% of all grit 75 micron and larger at the design flow rate when used with a Hydro International washing system
- Outputs 60% Total Solids and less than 15% Volatile Solids when used with a SlurryCup™ or TeaCup®
- Dewatering capacity from 1 - 10 yd3/hour of grit (0.76 - 7.65 m3/hr)
- Clarifier sizes from 48" to 96" square (1.23 to 2.44 m)
- Belt widths range from 6" to 57.5" (0.15 to 1.46 m)
- 304 stainless steel construction standard; 316 stainless steel available
- NEMA 4X valves and stainless steel control panel
- Variable frequency drive
- Belt rinse system
- Belt housing is lined with abrasion resistant urethane for long product life
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When should we use a Grit Snail and when should we use Hydro's Grit Decanter for a dewatering system?
Larger plants will typically require a Grit Snail® system, while in many smaller plants a Grit Decanter system will provide the required dewatering performance more economically. Please contact us to determine whether a Grit Snail® or Grit Decanter dewatering system would be the optimal choice for your plant.
Can the Grit Snail be used with grit removal devices from other manufacturers?
No, the Grit Snail® is designed specifically for dewatering clean grit output from Hydro International’s high performance separation and washing devices. Other systems will output grit with high organic content and cannot be dewatered by a Grit Snail®. Alternative systems typically do not capture the fine grit particles that the Grit Snail® is designed to retain – and would not require the outstanding performance and dewatering capacity of the Grit Snail®.
What are the advantages of the Grit Snail?
Many conventional grit removal systems combine washing and dewatering in the same process. This introduces turbulence, which stirs up the captured fine grit particles, allowing them to be released with the effluent water. The Grit Snail® is only used for grit dewatering. The slowly moving belt of the Grit Snail® pulls solids from the clarifier water without agitating the water, thereby retaining even very fine grit particles.