As environmental protection requirements become increasingly stringent, the requirements for solid-liquid separation efficiency in water treatment processes continue to increase. As an efficient and compact separation equipment, the rotary disk filter has gradually become one of the core equipment in the fields of municipal sewage, industrial wastewater treatment and tap water purification. With its unique structural design and intelligent operation mode, it plays a key role in reducing suspended solids in the effluent and improving water quality stability.
1. Core structure: precise combination of modular design
The structure of the turntable filter revolves around "high-efficiency filtration + automatic backflush" and is mainly composed of five major components:
1. Turntable assembly: The core part consists of multiple filter discs arranged in parallel. Each filter disc is disk-shaped and covered with filter media. There is a water collection channel inside the filter plate, and the filtered water is collected and discharged through the channel.
2. Filter media: Choose different types according to processing needs, such as polyester fiber filter (precision 10-100μm), microfiltration membrane (precision 0.1-10μm) or metal mesh. The media material needs to be acid and alkali resistant and wear-resistant, and common ones include PVDF, stainless steel, etc.
3. Backwash system: including backwash pump, compressed air pipe and mud discharge device. When the filter disc intercepts too many impurities, the contaminants are stripped off through combined air and water backwash to ensure recovery of filtration efficiency.
4. Driving device: A low-speed motor is used to drive the turntable to rotate (speed 0.5-2r/min), so that each filter plate can evenly contact the sewage and avoid local blockage.
5. Control system: Automated operation is realized through PLC+ sensors (pressure difference, liquid level, flow rate), real-time monitoring of the inlet and outlet water pressure difference, and automatic triggering of backwashing without manual intervention.
2. Working principle: Synergy of dynamic filtering and intelligent recoil
During normal operation, the water to be treated enters from one side of the equipment and flows through the medium on the surface of the filter plate. Suspended particles, algae, colloids, etc. in the water are intercepted, and the clean water passes through the medium and enters the water collection pipe for discharge. As the filtration time increases, the retained material on the surface of the filter plate thickens and the filtration resistance increases (the pressure difference between the inlet and outlet water reaches 0.03-0.05MPa), and the control system starts backwashing:
- Stop water inflow, open the backflush valve, and use high-pressure clean water (or compressed air) to reversely flush the filter plate to flush impurities to the bottom sludge tank;
- The backwashing time is only 30-60 seconds, and the water consumption is only 1%-3% of the treated water volume, which does not affect continuous operation;
- After the backflush is completed, the equipment resumes normal filtration and the cycle repeats.
3. Application scenarios: covering water treatment needs in multiple fields
Rotary disk filters have a wide range of application scenarios, especially suitable for areas with strict requirements on suspended solids:
- Municipal sewage treatment: In-depth treatment after secondary treatment to remove remaining SS (suspended solids) and phosphorus, so that the effluent reaches the first-level A standard (SS≤5mg/L). For example, after a certain urban sewage treatment plant adopted this equipment, the effluent SS was stabilized below 3mg/L, meeting the requirements for recycled water reuse.
- Tap water purification: Pretreatment unit removes algae, sediment and organic matter from raw water, reducing the burden of subsequent processes (such as ultrafiltration, reverse osmosis).
- Industrial wastewater treatment: Wastewater from food processing (beer, dairy products), papermaking, printing and dyeing, etc., separates large amounts of suspended solids, reduces COD/BOD, and creates conditions for subsequent biochemical treatment.
- Desalination pretreatment: removes plankton and particulate matter from seawater and protects the reverse osmosis membrane from clogging.
4. Core advantages: performance beyond traditional filtration equipment
Compared with traditional equipment such as sand filters and sedimentation tanks, rotating disk filters have significant advantages:
1. Small footprint: The modular design can be stacked vertically and is only 1/3-1/5 of a sand filter, making it suitable for projects with limited space.
2. High filtration precision: The media precision can be adjusted according to needs to meet different water quality standards (such as drinking water, recycled water).
3. Low operating cost: less water consumption for backwashing, low power consumption, and simple maintenance (replace the filter membrane or clean the filter screen regularly).
4. Strong impact load resistance: can adapt to fluctuations in water quality and quantity to ensure stable water output.
5. High degree of automation: the entire process runs automatically, reducing manual operations and reducing management costs.
5. Technology upgrading: developing toward intelligence and high precision
In recent years, turntable filters have continued to iterate:
- Membrane integration technology: Combining the microfiltration membrane with the turntable, the filtration precision is increased to 0.1μm, which can remove microorganisms and small molecule pollutants;
- Intelligent monitoring: Remote real-time monitoring is realized through Internet of Things technology, big data analysis predicts filter membrane life, and maintains in advance;
- Corrosion-resistant materials: using stainless steel, PVDF and other materials, extending to the field of high-salt and high-acid wastewater treatment.
Conclusion
With its high efficiency, compactness and intelligence, the rotating disk filter has become an indispensable equipment in the modern water treatment process. It not only helps sewage discharge meet standards, but also provides technical support for water resource recycling, which is of great significance in promoting green environmental protection and sustainable development. In the future, with the improvement of material technology and intelligence level, rotating disk filters will play a greater role in more fields and contribute to water environment protection.
(The full text is about 1050 words)
