Shafted Biosolids Load-Out System Ewing-Lawrence Sewage Authority Lawrenceville, NJ

General Description

The Ewing-Lawrence WWTF is located in Lawrenceville, NJ and designed to process 16 million gallons per day (MGD) of wastewater. The plant serves the townships of Ewing and Lawrence, New Jersey, which combined includes approximately 65,000 residents and local businesses. The plant has undergone many rounds of repairs and upgrades through the years of operation. The most recent upgrades included rebuilding three belt filter presses and replacement of the biosolids load-out system.

Each of the three belt filter presses provides dewatered biosolids to an independent load-out system and fills 53-foot trailers. Each load-out system consists of a collection screw conveyor and a load-out screw conveyor. Each load-out screw conveyor is fitted with 6 discharges and 5 electrically-operated slide gates located above the trailers. Via sequential control of the gates, a trailer is evenly loaded without the need for manual leveling of the dewatered biosolids.

The grit is dewatered and lifted by the screw conveyors to dumpsters. The equipment is exposed to the elements and corrosive gases present at the headworks. The new screw conveyors provided by KWS Environmental were designed with abrasion and corrosion resistant materials.

Design Parameters

1. Product Type: Dewatered Biosolids
2. Material Density: 60 Lbs. per Cubic Foot
3. Capacity: 350 Cubic Feet per Hour
4. Duty: 5 Days a Week, 8 Hours per Day

KWS Advantages

KWS Environmental was originally selected to provide only the slide gates for the project. The Ewing-Lawrence Sewage Authority was so pleased with the quality and fast delivery provided by KWS for the slide gates that they decided to order the three load-out systems from KWS as well. Due to space constraints and preference, the existing screw conveyors were replaced with the exact same diameter and discharge locations as the previous design.

KWS designed the new load-out systems to accommodate the existing structure and belt filter presses. Also, KWS added flexibility to the design to reduce the likelihood of installation and fit-up conflicts. KWS engineers provided on-site start-up, maintenance, and training services for the equipment. Due to operational constraints as a working sewage treatment plant, the upgrades to the biosolids load-out system had to be completed in three stages.

Special Features

The new KWS Environmental biosolids load-out system utilized shafted screw conveyors. Shafted screw conveyors are very cost effective when compared to shaftless screw conveyors and there are no trough liners to replace. Periodic maintenance and replacement of the CEMA hanger bearings are the only internal maintenance item for the conveyors. Ribbon screws were used to handle the sticky dewatered biosolids and prevent accumulation. CEMA standard components were used for the screw conveyors wherever possible. Spare parts are readily available and stocked at KWS as well as authorized distributors.

The new KWS Environmental slide gates were designed for long-term service and corrosion resistance. The slide gate design included drip-resistant seals, drip rails, and electronic control. Each gate was equipped with an AUMA multi-turn actuator. The rack-and-pinion design provides efficient and quick response to operator input.