Hydro launches grit dewatering solution

Hydro says that the products can be combined with a Hydro grit removal system and are suitable for new, expanding or upgrading wastewater treatment plants with a peak capacity of up to 10 mgd, or as a replacement for worn out or ineffective grit treatment systems.

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. The organics collected with the grit can retain water and decompose, creating odours. 

“Many smaller and medium-sized treatment plants have struggled with the cost of grit-related maintenance from abrasive wear and deposition of grit,” said Adam Neumayer, operations director for Hydro International’s Americas’ water & wastewater solutions division.

Grit removal

This new process operates by taking the concentrated grit slurry from the grit removal system and introducing it tangentially into the GritCupat 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 centre 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.

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 ?ow.

Preventing abrasion

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.

The GritCup and SpiraSnail combination has no washwater requirements and is also suitable for intermittent or continuous treatment. The products will be demonstrated to visitors at WEFTEC 2014 in September.