Sludge Type: Mixed Waste Digestate (source: various industrial feedstocks and municipal wastewater treatment sludge)
Challenge: Very abrasive and rough sludge needed to be dewatered with the cleanest possible filtrate, causing no damage to equipment. Compounding the difficulty, no wash water could be used in the process.
Solution: Esmil xJD Roller Press for Sludge Dewatering
The Esmil xJD Roller Press was selected as the ideal solution for this challenging sludge dewatering application. This system is specifically designed to handle:
- High concentrations of abrasive materials.
- Sludge with a large amount of fibrous and solid waste inclusions.
- Debris that could clog traditional dewatering equipment.
The mixed waste digestate produced at the biogas plant, derived from diverse feedstock, contained significant amounts of sand, stones, and other debris. The dry solids content in the digestate ranged from 6% to 9%, further complicating the dewatering process.
Performance Goals
The primary objective for the xJD Roller Press was to achieve:
- A stable dewatering process.
- High-quality filtrate.
- High dry solids content in the dewatered sludge.
- Low polymer consumption for cost-efficiency.
Custom Engineering for Optimal Performance
Leveraging its extensive experience in digestate dewatering, ESMIL developed a tailored solution based on the xJD Roller Press, which included several advanced features.
Two-Stage Flocculation System: Adjustable turbulent and laminar modes to optimize flocculation.
- In-Line Turbo-Mixer (Floccstirrer): Ensures effective and consistent flocculation.
- Filtrate Recycling: For improved water management.
- Multi-Position Chemical Dosing: Precise and flexible reagent dosing to minimize polymer usage.
xJD Roller Press: Advanced Dewatering Technology
The Esmil xJD Roller Press is a patented technology designed to dewater even the most difficult sludge types with maximum efficiency. The press operates using a series of rollers that compress the sludge, squeezing out moisture through specially designed slots. These slots are mechanically self-cleaning, preventing clogging from sticky or greasy sludge and allowing for consistent water removal.
Compression is adjustable at the press outlet through a tensioning mechanism, ensuring optimal results for each application. Most of the filtrate is separated early in the process, where the pressure on the sludge is minimal, helping to keep solids within the system and maintain a clean filtrate. The discharge zone, which measures approximately 1500 mm x 100 mm, is large enough to handle oversized debris such as stones, wood, metal, and plastic.
The system operates without using wash water, with the filtration surface cleaning itself during operation.
Results at the Biogas Plant, Cleveland, Ohio
The ESMIL xJD Roller Press xJD-1500 delivered the following performance at the biogas plant:
- Dry Solids Processing Capacity: 1,323 lbDS/h.
- Inlet Dry Solids Content: 6% to 9%.
- Outlet Dry Solids Content: 25% to 27%.
- TSS in Filtrate: 600 – 800 ppm.
- Polymer Consumption: 30 lb/ton DS.
These results met the client’s requirements, providing a clean filtrate suitable for further treatment. The machine operated reliably without significant wear due to its robust design.
Conclusion: The Esmil xJD Roller Press proved to be a highly effective solution for this biogas plant. It handles the abrasive, mixed waste digestate without the need for wash water and delivers stable performance. The xJD Roller Press is available in models up to 2 meters wide, supporting high throughput capacities of up to 2,000 lbDS/h.
