Shaftless Screw Conveyors with Ceramic-Lined Troughs Rensselaer County Sewer District in Troy, NY

General Description

Rensselaer County is in New York State near Albany. Rensselaer County Sewer District protects the Hudson River by providing secondary treatment to the wastewater before it is discharged. Secondary treatment involves removal of 85-percent of both the Carbonaceous Biochemical Oxygen 5-Day Demand and Total Suspended Solids from the influent wastewater.

Due to age and increased demand, District 1 Wastewater Treatment Facility required improvements. Chazen Engineering provided the design for a $3 million improvement project. Improvements to the 24 MGD activated sludge treatment plant included the replacement of the primary clarifier internals, grit/primary sludge pumps and piping, primary sludge grit removal equipment, primary clarifier inlet channel aeration piping and diffusers, and existing plant water pumping systems and intake strainer. These improvements allowed the treatment facility to comply with the Albany Pool Combined Sewer Overflow Long Term Control Plan. As part of the new grit removal equipment, KWS engineered a system of shaftless screw conveyors to handle grit from grit classifiers and transport it to load out dumpsters.

Design Parameters

1. Product Type: Grit
2. Material Density: 90 to 120 Lbs. per Cubic Foot
3. Capacity: 180 Cubic Feet per Hour
4. Duty: 7 Days a Week, 24 Hours per Day

KWS Advantages

KWS Environmental provided the design to Chazen Engineering for a shaftless screw conveyor for grit removal. Chazen Engineering frequently specifies KWS Environmental equipment because of many successful projects in the Northeast. The existing equipment was old, rusted-out, and in dire need of replacement. The existing conveyor on the second-floor discharged grit into a no-longer-working diverter chute and then a makeshift plastic pipe to a dumpster below. The new solution provided by KWS Environmental was fully enclosed to reduce the odors and mess of the old system.

The original design for the grit load out system was not feasible. Schultz Construction and KWS discovered that the existing sludge belt conveyor and catwalk caused interference and the system would not work as designed. Working with Chazen Engineering, KWS and Schultz provided an arrangement that would work in the extremely tight space. The new design was simplified and created a more long-lasting solution.

Based on field measurements, KWS modeled the building accurately using 3D Autodesk Inventor eliminating any interferences between equipment and structures. The accuracy of the design submittal was approved with very few comments from Chazen Engineering. An engineer from KWS Environmental provided start up assistance and training. Everything went great and the equipment was put into service right away.

Special Features

The KWS Environmental shaftless screw conveyors were constructed from 304 stainless steel for corrosion resistance. KWS shaftless spirals were made from the exclusive KWS-350 micro-alloy material that is the strongest and toughest spiral on the market. The troughs were lined with ½-inch thick ceramic tiles, ensuring a tremendously long operating life while handling the abrasive grit. KWS ceramic liners typically last the life of the equipment. The load out conveyor was designed to be reversing so two discharge dumpsters could be utilized without interrupting operations. The electrical components were designed to be explosion-proof, typical of headworks environment. The structural supports for the new screw conveyors were completely adjustable and required no modifications in the field.