The Ecologix Multiplate Screw Press: Efficient Sludge Dewatering

Introduction

Ecologix Environmental Systems, based in Alpharetta, Georgia, manufactures a line of fully automated Multiplate Screw Press (MPSP) models designed for efficient sludge dewatering. As the core of a dewatering station in treatment trains, the MPSP supports operators and facility managers in reducing sludge hauling costs.

The MPSP transforms liquid sludge (0.2-5% solids, 2,000-50,000 mg/L) into a dry cake (~20% dry solids, 200 g/kg). It is typically mounted on a mezzanine platform constructed from carbon steel, which is powder-coated or galvanized. This elevated platform enables gravity discharge of the dry cake directly from the screw press into roll-off containers.

The system often includes a polymer make-down unit for easy activation and dosing, typically using polyacrylamide (PAM), the most effective thickener for producing a dry cake from sludge. For sticky or oily sludge, a diatomaceous earth (DE) feeder may be integrated to enhance performance.

How It Works

The MPSP processes sludge through a sequence of flocculation and dewatering:

• Flocculation: Sludge enters a flocculation tank where polymer is fed, aggregating solids into flocs.
• Dewatering: The flocculated sludge flows into a cylindrical dewatering chamber
• Self-Cleaning and Discharge: This line of screw presses includes self-cleaning to prevent clogs and build up. Filtrate is collected below the rings in a reservoir which is pumped back to the equalization tank for reprocessing, while the dry cake drops via gravity from the elevated platform into roll off containers which are transported to the local landfill.

Technical Specifications

• Electrical: Operates on 3-phase, 480V power, using ~ 0.5-1.5 kW per motor
• Return on Investment: Accounting for the CapEx, additives, electricity, and landfill costs, a dewatering station tends to deliver favorable ROI when sludge haul-off costs reach ~$20,000/month.