Centrifuge Diverter Gate for Dewatered Sludge St. George, UT Sewage Treatment Plant

General Description

The St. George Wastewater Treatment Division operates a wastewater treatment facility that accepts sanitary sewage from St. George, Ivins, Santa Clara, and Washington City in southern Utah. The treatment plant has a design capacity of approximately 17 million gallons per day (mgd) and currently treats an average of 9.5 mgd. The plant uses an oxidation ditch / extended aeration process that uses physical and biological processes to treat the sewage. As part of a system for producing sludge cake, a diverter gate was required at the discharge of a centrifuge. The gate provided a reliable means to divert low solids sludge away from the existing conveyor while the centrifuge gets up to speed. Centrate, or low solids sludge was diverted to a drain and re-introduced to the process stream. Once the centrifuge was operating at peak efficiency, higher solids sludge was discharged to a loading conveyor below. KWS designed, manufactured and delivered the diverter gate directly to the St. George Wastewater Treatment Plant.

Design Parameters

KWS Advantages

The St. George Wastewater Treatment Plant had recently purchased a new centrifuge to add to their existing dewatering building. KWS Environmental provides custom-designed diverter gates to comply with the unique conditions of each application for almost every centrifuge manufacturer. KWS produced a fully engineered system including design (mechanical and instrumentation) that fit into the limited available space and included the required design features. KWS’s engineers interfaced with the Customer’s engineering firm to understand the key parameters. The diverter gate was designed to integrate with the centrifuge and the worst-case operating conditions of the system. The gate opening utilized the full length and width of the centrifuge discharge opening to allow for complete discharge of dewatered sludge cake.

Special Features

The chute between the centrifuge and diverter gate contained large diameter drain connections to allow the low-solids centrate to be removed when the gate was closed. KWS Environmental designed a diverter gate with a special neoprene bulb seal right above the gate blade to ensure that no low-solids material leaked past the gate. The KWS Diverter Gate featured 304-stainless steel, bronze-bushed rollers for low resistance gate movement. The gate’s pneumatic actuator and pre-wired solenoid valve and limit switches were designed to meet the specific application requirements including opening and closing speed and interfacing with the centrifuge control system. KWS also supplied a ball valve, air filter/regular, and junction box to allow for quick installation and wiring of the new gate. The complete gate body was manufactured from 304-stainless steel and was water-tight.