Water and wastewater treatment

SpiraSnail Compact

Small footprint grit dewatering classifier designed to fit in plants with limited space.

The SpiraSnail^® Compact is smaller than many conventional grit classifier systems. With a shorter length, width, and height - the system is designed to fit into tight spaces. Engineered for easy maintenance, the SpiraSnail^® Compact is the right fit for treatment plants of all sizes.

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The SpiraSnail^® Compact is a high efficiency grit dewatering unit that captures and dewaters fine grit, sugar sand, silt, snail shells, and high density fixed solids. When combined with a HeadCell^® or Grit King^®separator it provides a complete high performance fine grit removal system.

Applications

Improved wastewater management
New wastewater treatment plants
Treatment plant retrofits & performance upgrades

Big Performance for Smaller WWTPs

Clarifier designed to optimize settling and reduce velocity
Shafted, self-bedding screw eliminates need for maintenance intensive wear bars or liners
Easily accessible external lower bearing with a gasketed cover provides easy maintenance and eliminates the risk of leaking if bearing fails
No plant water required to operate
Large internal clearances and removable access hatches simplify maintenance
Smaller in height, width, and length than many conventional grit classifiers allows the system to fit in places other dewatering systems cannot

Innovative Clarifier Design

With its unique design, the clarifier on the SpiraSnail^® Compact optimizes the settling tank characteristics and grit capture. Built on the same design principles found in all Hydro products where retention time and surface overflow rate are key criteria, the influent baffle forces flow to travel across the full clarifier area. The screw is protected by a cover which prevents wash out of fine grit.

Efficient Dewatering Design

Most classifiers and grit washers are incapable of retaining fine grit particles due to the use of an undersized clarifier tank or rapidly turning screw. The SpiraSnail^® Compact has been designed to address these weaknesses. The innovative clarifier design provides increased surface area while the shallow incline and slow screw speed (2 rpm) allows 95% capture of 106 μm and larger grit particles.

Screw and Bearing Improvements

The SpiraSnail^® Compact uses a shafted screw design with an external lower bearing. Unlike classifiers with shaftless screws there is no need for liners or steel wear bars that are difficult to replace, typically requiring a complete disassembly of the unit. Instead, the SpiraSnail^® Compact is equipped with a long lasting 4-bolt lower bearing that can be accessed and serviced from the outside of the screw trough saving both money and downtime.

OpTeaCup™ & SpiraSnail^® Compact System

For larger plants with higher capacities a grit concentrator may be needed to reduce volume. The OpTeaCup™ grit concentrator reduces influent to the SpiraSnail^® Compact to < 20 gpm which improves performance to 95% capture of 75 μm and larger grit particles.

Feed is pump or gravity fed from a Hydro International grit separator or washer. Flow enters from the top of the system into a deflector which directs the flow into the clarifier, away from the effluent weir. Water travels across the clarifier area while grit settles to the bottom.

Once grit has been removed, clarified water passes over a low velocity weir which prevents fine grit from bypassing and entering downstream processes. The clarified water is sent back into the wastewater stream.

After reaching the clarifier bottom, grit is conveyed by a slow rotating screw. The grit is dewatered while it is transported towards the discharge chute to be deposited in the grit receptacle, ready for disposal.

SpiraSnail cutaway

Design Notes

All Stainless Steel heavy-duty design ensures long product life
Optional explosion proof motor
Control panel VFD allows easy speed adjustment
System is only used for dewatering which minimizes turbulence and allows slower auger speeds and intermittent operation

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