Belt Filter Press or Screw Press? Why Modern WWTPs Are Switching to VOLUTE™
Why modern Wastewater Treatment Plants (WWTPs) are switching from belt presses to VOLUTE™ technology.
The belt filter press is becoming a technological relic as the VOLUTE™ screw press defines a new standard in TOTEX efficiency and operator comfort.
The End of the 'Wet Hall' Era and Endless Maintenance
Traditionally, a belt filter press is an open device. This design inevitably fills the hall with high humidity, aerosols, and odors, leaving floors slippery and wet. In some cases, such environments have become so overgrown with mold that operators were afraid to enter.
In contrast, VOLUTE™ is a fully enclosed system. It eliminates splashes and odors, providing a dry, safe, and professional working environment.
Water Consumption: The 'Free Water' Myth
The belt filter press is a dewatering paradox: it is a technology designed to remove water, yet it consumes thousands of liters of high-pressure water per hour to prevent belt clogging.
It is a common misunderstanding that this wash-water is “free” for a WWTP. In reality, this water returns to the system as contaminated filtrate, creating a costly loop where you must pump and re-treat the same liquid again. You are paying “double costs”—first for the initial treatment of the water and then for the energy and chemicals required to process it again once it leaves the belt filter press.
The VOLUTE™ self-cleaning mechanism, combining fixed and moving rings, requires only a fraction of wash-water and operates at standard pressure (2–4 bar).
Operation: From 'Belt Watcher' to Automation
A belt filter press requires constant attention – monitoring belt misalignment, checking tension, and manual cleaning are the daily bread of operators.
VOLUTE™ follows the “Switch on and go do something more useful” system. It is designed for fully automated 24/7 operation without the need for constant supervision.
CASE STUDY: A Direct Comparison
Source: Study “VOLUTE DUO™ vs Belt Filter Press”, Evergreen Water Solutions (Scotland, UK).
Sludge Type: Mixed Municipal Sludge
- Primary sludge (from settling tanks).
- Secondary (surplus activated) sludge from the biological stage.
- Imported sludges.
The sludge was thickened before dewatering to ensure optimal efficiency for both technologies during the comparative test.
Note: Unlike the belt filter press, VOLUTE™ technology does not require a separate pre-thickening stage for its optimal performance, as it handles low-concentration sludge directly.
Dewatering Quality and Filtrate Clarity
The goal of the study was to achieve dry solids (DS) above 20% and a capture rate above 95%.
| Parameter | Belt Filter Press | VOLUTE DUO™ |
|---|---|---|
| Average Cake Dryness (DS) | 19.5 % | 20.2 % |
| Filtrate Clarity (Capture Rate) | 92.0 % | 98.7 % |
| Polymer Dosing | 12.5 kg/t DS | 10.2 kg/t DS |
Operational Costs and Resources
| Metric | Belt Filter Press | VOLUTE™ | SAVINGS |
|---|---|---|---|
| Wash-water Consumption | 18,200 l / hour | 168 l / hour | 99.1 % |
| Average Power Consumption | 6.5 kW | 3.1 kW | 52.3 % |
| Max. Measured Power Input | 14.25 kW | 5.2 kW | 63.5 % |
Strategic Benefits (TOTEX)
When you look at the Total Cost of Ownership (TOTEX), VOLUTE™ offers advantages that go beyond just the machine itself.
- Increased Plant Capacity: By saving 250 m³ of wash-water per day, the plant stops “recycling” dirty water. This immediately frees up the hydraulic capacity of the entire treatment plant. You can process more waste without building new tanks.
- Optimized Flocculation: The VOLUTE DUO™ uses a specialized mixing tank supported by the static or dynamic mixer to build strong flocs (clumps of sludge). This optimized process allows the machine to achieve better results while using less polymer (chemicals).
- Lower Maintenance: You no longer need to pay for expensive replacement belts or repairs to high-pressure wash-water pumps. The stainless steel rings in the VOLUTE™ last for many years.
VOICES FROM THE FIELD: What do the operators say?
“With the old belt, I had to constantly watch if it was misaligning or if the belt was starting to tear. With VOLUTE™, I hardly know the machine is there. I turn it on in the morning and go do other work. It’s a huge difference in mental well-being.”
— Senior WWTP Operator
“What surprised me most was the silence and the dryness. Before, there was a constant mist from the spraying in the hall and the smell was everywhere. Now I can go there in office shoes. Plus, I no longer have to clean high-pressure nozzles, which was the worst job.”
— Maintenance Technician
CONCLUSION: An Investment That Pays for Itself through Savings
Replacing a belt filter press with VOLUTE™ is a strategic decision. It is an investment that pays for itself by reducing energy, water, and chemical costs while creating a better environment for your team.