Screenings Conveyance for Blackhawk WWTP Friendswood, TX

General Description

Blackhawk WWTP is solely dedicated to regional treatment of municipal sewage, serving the City of Friendswood, Harris County Municipal Utility District (MUD) 55, Baybrook Municipal Utility District 1, and extreme southern portions of the City of Houston. The 2013 Blackhawk WWTP Rehabilitation project included the installation of new headworks equipment with two new bar screens and auxiliary conveying equipment.

The plant was originally built in 1979 and is currently designed for 9.25 million gallons per day (MGD). Operating on the gulf coast, the plant has a responsibility to the community to stay in good condition. The rehabilitation project improved the headworks process to better protect the primary process and equipment. Properly operating headworks equipment provides an easily maintained and properly running plant. The screening system is tasked with removing large items such as rags, rocks, trash and other man-made and natural debris.

KWS Environmental provided a shaftless screw conveyor to transfer screenings materials from the two new bar screens to a washer compactor. The screenings were then washed, compacted and loaded out to trailers for disposal.

Design Parameters

1. Product Type: Dewatered Screenings
2. Material Density: 60 to 65 Lbs. per Cubic Foot
3. Capacity: 180 Cubic Feet per Hour
4. Duty: 5 Days a Week, 8 Hours per Day

KWS Advantages

KWS Environmental was selected to provide a conveyor to transfer screenings material from the two screens to the washer compactor. KWS chose a shaftless screw conveyor for the application because the irregular size of the screenings can easily be handled without issue. The screenings material was then transferred to a washer compactor to wash and reduce the volume of screenings. The KWS engineering team coordinated with the screen manufacturer to ensure seamless interfacing of equipment.

KWS communicated effectively though out the project with the contractor and end user to ensure deliverables were provided when needed. KWS also provided onsite supervision and assistance during the installation and testing process and made subsequent visits after initial operation to ensure all issues were resolved. Operation and maintenance training was also conducted with the plant staff.

Special Features

The KWS Environmental shaftless screw conveyor was constructed from 304 stainless steel for corrosion resistance. The shaftless spiral was 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 virgin UHMW to support the shaftless spiral. The UHMW liners were installed in 4-foot long sections for easy removal and replacement. Since the screening system is located near the gulf, the conveyor was completely sealed and water-tight. The shaftless spiral included an inner spiral to improve conveying efficiency and reduce the chance of material plugging.

The conveyor was equipped with an Milltronics underspeed system to shutdown the conveyor if a plug develops. The drive shaft for the KWS shaftless screw conveyor is machined from solid bar stock, which KWS guarantees for the lifespan of the equipment. KWS designed the custom support structure to be bolt-together in the field so no welding or field modifications were required.