Vortex Grit System Replacement

We Can Replace Your Existing vortex Grit system
to Perform Like New regardless of original manufacturer

Advantages of Vortex Grit System Replacement

The headworks of a wastewater treatment plant can be degraded by biogenic corrosion. Grit removal equipment is critical to the operation of the wastewater treatment process. Sulfuric acid is formed biologically and can corrode concrete and steel structures and equipment. Grit removal equipment can be affected by this process. Motors, gearboxes, bearings, valves and fittings can have accelerated wear and tear. Materials such as cast iron or ductile iron can be especially prone to accelerated corrosion. Hydro-Dyne Engineering can replace equipment within a vortex grit removal system regardless the manufacturer to establish original performance. 

Why Hydro-Dyne Engineering for Grit System or Component Replacement

    1. US-Based supply chain with parts and service based in Clearwater, Florida
    2. Existing equipment OEM not readily available
    3. Price from existing OEM not agreeable
    4. Delivery time and/or service availability not readily available
    5. Technical support from existing OEM not available

 

Hydro-Dyne Engineering is an original equipment manufacturer of a full range of vortex grit removal equipment. Parts and service can be supplied to replace aged or non-performing equipment. A service visit to provide system diagnostics is available if needed.

Benefits of Grit Removal Performance

  1. Accumulation of Grit Impedes Aeration – Decreased air/oxygen can have detrimental effects, such as reduced ammonia conversion and nutrient removal from the process.
  2. Accumulation of Grit Reduces Aeration Capacity – Grit that accumulates in an aeration tank reduces the holding time available and, therefore, if not addressed can compromise the treatment process.
  3. Grit is hard abrasive material that wears on rotating parts, such as return activated sludge pumps.
  4. Accumulation of Grit Reduces Sludge Holding Capacity – Grit is inorganic material that can get deposited into the primary and secondary sludge. While typically a small amount, grit that is not removed in preliminary treatment takes capacity away from sludge removal and dewater processes. Grit that accumulates in the digestion process can reduce the residence time needed.

Grit Slurry Dewatering

Grit that settles in the bottom of a grit settling tank is typically a slurry consisting of 98% water and 2% or less solids made up of fine sand, shell, bone and other fine solids larger than 300 microns in size. Grit slurry is then pumped to be further dewatered by a cyclonic device followed by additional settling. The schematic below provides a diagram of the grit slurry removal and dewatering process. Note the grit pump can be configured in two ways, either on top of the tank to provide a suction lift or as shown below with a flooded suction supply from the tank bottom. The diagram is also simplified and does not show a fluidizing line used to keep grit slurry in suspension for transport to the dewatering process.

The following vortex grit removal equipment can be considered for replacement:

A typical impeller assembly is shown for a concrete grit tank with a sloped floor design. Common replacement items include the motor and/or gearbox located at the top of the assembly. The impeller used in this design is typically submerged and can be replaced as well. An impeller assembly design for a sloped floor grit tank is included in the image shown. It is important to note that this assembly is specific for a flooded suction grit slurry pump. A different impeller design is utilized for a grit slurry removal pump mounted on top of the tank.

 

A typical propeller assembly is shown for a concrete grit tank with a flat floor design. Common replacement items include the motor and/or gearbox located at the top of the assembly.  The propeller used in this design is typically submerged and can be replaced as well. 

A propeller assembly design for a sloped floor grit tank is included in the image shown. It is important to note that this assembly is specific for a top mounted grit slurry pump. Note the flange on the top of the assembly near the motor used to connect to a grit slurry pump influent. A different propeller design is utilized for a grit slurry removal pump mounted on at the bottom of the grit tank.

Hydro-Dyne can fabricate tanks from stainless steel. These are typically used for smaller grit removal tanks. These tanks with systems below a flowrate threshold of 5 MGD. A small 6’ diameter sloped floor grit removal tank is shown below.  The overall tank height on this design is 10’ tall. Stainless steel can have pitting or crevasse corrosion if the tank was not initially passivated correctly. Hydro-Dyne can provide a replacement tank if corrosion is advanced.

A pump is commonly used to remove grit slurry from the grit settling tank.  The pump is specialized to handle highly abrasive slurry. The grit slurry pump can have a flooded suction as shown in the schematic above or be mounted on the top of the grit settling tank to draw grit from the tank bottom to the pump impeller. A centrifugal single stage pump with casing and recessed impeller design is used for this service as grit slurry is abrasive to rotating equipment. The recessed impeller has the capability to transport solids with low propensity to bind rotating parts.  

The grit classifier is a key component used to dewater grit slurry from a grit removal tank. A cyclone is commonly used to remove 90% of the water from the grit slurry before it enters the grit classifier. A grit classifier is composed of a small settling tank for grit where an auger transports grit out of the settling zone to a final disposal vessel that is either a dumpster or bag. Grit slurry is extremely abrasive and can wear down any rotating equipment in contact. A schematic below shows a 3D view of a grit classifier with cyclone.

Hydro-Dyne's no-hassle vortex grit removal equipment replacement process:

Get customer input to understand recognized equipment needs

  • Talk through all concerns the customer has related to equipment
  • Ask questions and advise inspection of equipment typical wear areas
  • Gather photos to help with scope assessment

Require and recommend a scope of work for appropriate replacement equipment

  • Document what work is required and what is recommended
  • Coordinate with estimate and agree upon scope of work
  • Quote a cost for equipment

Replace agreed to equipment

  • Order materials
  • Make and assemble all replacement equipment
  • Where necessary, test replacement equipment
  • Ship replacement equipment

Re-installation Support to Ensure Achieved Results (Optional)

  • Verify installation is correct
  • Commission the equipment for intended use