A “Revolution” in low-density sludge processing
The Problem with Conventional Screw Press Dewatering
Screw presses are a simple way of dewatering sludge and provide robust operations with low-cost maintenance. Typically, they have a single bearing or bushing at one end and a gear drive at the other end with openings in the casings that allow fluid to escape as the sludge is pressed. However, when these openings are too small, they plug up, so openings must be made adequately large. But, if sludge is pressed too hard, it extrudes through the openings. For many sludge applications, those simple mechanical limitations render traditional screw presses inadequate to achieve solids which are dry enough. A better dewatering technology is needed.
The Solution is the Multi-Disc Dewatering Concept
The key to the Trident MD Press dewatering process is the “dewatering cylinder”. This cylinder can achieve sludge thickening and pressing (dewatering) in a single integrated operation. The MD Press can take sludge as dilute as 0.1% solids directly from a treatment process, including an oxidation ditch or clarifier, and produce a cake of over 20% solids. Separate thickening, storage and conditioning processes are eliminated. In addition, human operators, power consumption and water for operational wash-down are significantly reduced.
The Trident MD Dewatering Press System
The Trident MD Press is designed to be a fully automated system capable of starting up, operating and shutting down with no operator intervention. In addition to controlling the Trident MD Dewatering System itself, the control panel is designed to automate the polymer feed system, the unit sludge feed pump, as well as any conveyors required to remove dewatered cake. All components of the dewatering system work together, automatically starting up, operating, and shutting down as required. KPD Consulting can provide complete systems or work with other suppliers to provide an integrated package. In addition, unit operating and alarm outputs for connection to plant PLC/SCADA systems are standard.
• No need for regular operator attendance
• Produces high-quality filtrate, does not need to return to the head works (i.e. high solids recovery)
• Extremely low power consumption–up to 95% less than many other dewatering processes
• Low noise and odor generation
• Low wash water consumption
• Able to handle oily sludge
• Built-in flocculants dosing function
The Trident Multi-Disc Dewatering Technology
Unlike traditional screw presses, the Trident MD Press features a slow-speed, low wear screw within a unique “slip-disc” dewatering cylinder. Spacers and fixed rings are held in place on tie rods where the sliding rings, slightly smaller than the outer diameter of the screw and slightly narrower than the fixed rings, are gently moved by the screw. These sliding rings clean the fine gaps between the fixed rings and preventing clogging. The moving rings also cut into the sludge cake creating additional surface area and the release of more moisture. The initial section of the dewatering cylinder is the thickening zone where the filtrate is discharged. The final section of the cylinder compresses and dewaters the sludge as the pitch of the screw narrows and the gaps between the rings decrease toward the end-plate where solids are discharged.
Prior to the dewatering cylinder, the raw sludge is fed into a mixing tank where a polymer is thoroughly mixed. The sludge then passes through a flocculation tank where gentle mixing and flocculation occurs. From there, the sludge is channeled into the dewatering cylinder for pressing. The entire operation is controlled by the Trident MD Press control panel.