Grit Conveyor System for the Nacogdoches WWTP Nacogdoches, TX

General Description

The Nacogdoches Waste Water Treatment Plant (WWTP) is located in east Texas and processes an average of 12.88 MGD to provide service for over 33,000 people in the city and surrounding area. Like many Texas cities, Nacogdoches is steadily growing. With the maximum design load of 26 MGD, aging pipes and new customers, the load of grit to the plant will only increase in the coming years. In an effort to modernize, improve, and prepare for the demands of future growth, new grit removal equipment was installed to replace the worn existing equipment. KWS Environmental worked closely with the consulting engineer, the city, and the other suppliers to provide a simple solution.

Design Parameters

1. Product Type – Grit
2. Material Density – 60 to 115 Lbs. per Cubic Foot
3. Conveyor Capacity – 67 Cubic Feet per Hour
4. Duty – 5 days a week, 8 Hours per Day

KWS Advantages

KWS Environmental designed, manufactured, supplied and commissioned a grit conveyance system that included two shaftless screw conveyors to receive grit from two grit chains and discharge it to a dumpster. Custom inlet transitions between the grit chains and the receiving conveyor were designed to prevent spillage. KWS Environmental coordinated support locations with the local contractor. Designed to withstand the elements and the harsh nature of exposure to raw sewage, the heavy duty design of the new KWS grit screw conveyors placed an emphasis on maximizing the life of the wear components.

Special Features

KWS Environmental provided shaftless screw conveyors that were designed for the difficult application and to provide many years of uninterrupted service. The wear components in a shaftless screw conveyor are the shaftless spiral and the trough liners. KWS utilized our unique KWS-350 spirals for the application. Grit is extremely abrasive and will wear out typical shaftless spirals in a few years. The KWS-350 shaftless spirals are the hardest and toughest in the industry and specifically designed for grit applications. Most shaftless screw conveyor applications use plastic trough liners made from UHMW. UHMW wears relatively quickly in grit applications, requiring constant maintenance and replacement. KWS Environmental developed ceramic trough liners for very tough applications, such as grit conveyance. The KWS ceramic liners are ½-inch thick to provide superior wear life when compared to any polymer liner.

Another unique KWS Environmental design is our one-piece drive shaft. The drive shaft connects the drive unit to the shaftless spiral and transmits torque and rotation. KWS flanged drive shafts are machined from one piece of solid bar to eliminate the possibility of fatigue cracking at a welded joint on the shaft. The KWS one-piece drive shaft will never fail.

The motors and safety control devices for the shaftless screw conveyors were rated for the explosion-proof classified area. A flexible discharge chute was provided to allow for more precise filling of the dumpster and reduce spillage.