High Performance Grit Treatment Solution will be Demonstrated at WEFTEC

Hydro International (UK) has launched the GritCup and SpiraSnail, a combined solution that achieves high-performance grit washing and dewatering especially when combined with a Hydro grit removal system at the headworks of either municipal or industrial wastewater treatment plants.

The solution is ideal for new, expanding or upgrading wastewater treatment plants (WWTPs) with a peak capacity of up to 10 mgd or as a replacement for worn out or ineffective grit treatment systems.

The GritCup and SpiraSnail will be demonstrated to visitors at WEFTEC 2014 on Booth No 2317.

“Many smaller and medium-sized treatment plants have struggled with the cost of grit-related maintenance from abrasive wear and deposition of grit,” explains Adam Neumayer, Operations Director for Hydro International’s Americas’ Water & Wastewater Solutions Division.

Conventional washing and dewatering systems often lose fine grit particles sending them back to the process and contain a large volume of organics that increase the weight and volume of material to be disposed of. It is the organics that are often collected with the grit that retain water and decompose creating nuisance odours. The GritCup and SpiraSnail combination provides a new high-performance and lower-cost solution for grit washing and dewatering.

“Customers value the reliability offered by installing a complete grit removal solution from a single supplier.  Hydro can offer an entire system guarantee when the GritCup and SpiraSnail are installed with a Hydro headworks grit removal system, such as the Eutek HeadCell or Grit King separator.

"The response to our on-site GritCup and SpiraSnail development trials has been encouraging. Customers have been responsive to the technology which has rapidly resulted in contracts for industrial and municipal projects in North Carolina, Kansas and Michigan.”

Instead of conventional cyclones and screw classifiers that concentrate in the cyclone and attempt to wash and dewater in the classifier, Hydro has optimised each process in the GritCup and SpiraSnail and then combined them to provide a dual, high performance solution. 

With the integrated Hydro system, Hydro can guarantee 90 - 95% capture of all grit 106 micron and larger with less than 20% volatile solids and greater than 60% total solids in output grit at design flow.

The system retains a very high percentage of the total grit load preventing downstream abrasion damage and loss of treatment capacity - typically 75% of 75 to 106 micron grit is captured. The GritCup processes 200 gpm and the SpiraSnail has 0.75 yd3/hr conveying capacity.

This new process operates by taking the concentrated grit slurry from the grit removal system and introducing it tangentially into the GritCup at a controlled rate to establish a free vortex flow. The design of the vortex chamber effectively separates the grit to the perimeter where it falls via gravity into the boundary layer at the bottom of the unit. The boundary layer sweeps the grit to the center for collection. Excess water and separated organic materials flow out of the unit for additional processing.

A Hydro Reg-U-Flo vortex valve regulates the volume of washed grit slurry exiting the GritCup and introduces it tangentially into the SpiraSnail clarifier. Forced to the outside of the clarifier cone, the grit follows a predetermined path and settles into the SpiraSnail conveyor trough where it is dewatered by the slowly rotating screw as it is moved towards discharge. Clarified water is returned to the treatment plant.

As well as the benefits of its excellent grit and organics separation performance, the new GritCup and SpiraSnail combination has no washwater requirements. Further features include its suitability for intermittent or continuous treatment, an odour-reducing fully-enclosed design, heavy-duty stainless steel construction, easy maintenance access and large internal clearances to minimise blockage potentials.