In the chain of urban sewage treatment and water resource recycling, the pretreatment link is the key "gateway" that determines the efficiency of subsequent processes. Traditional grille equipment often faces pain points such as insufficient interception accuracy, easy clogging, and high maintenance costs. The emergence of internal flow plate-type fine grilles has become one of the core pretreatment equipment of modern sewage treatment systems with its unique structural design and efficient performance. It can not only accurately intercept tiny suspended solids, but also significantly improve the stability of the system, laying a solid foundation for subsequent biochemical treatment and deep purification.
1. Basic concepts and structural features
The internal flow plate fine grid is a precision filtration equipment with "internal flow" as the core design concept. It is mainly composed of four modules: grid assembly, slag cleaning system, driving device and control system:
- Grid assembly: Made of stainless steel 304 or 316L, it consists of multiple grids arranged in parallel. Precise wedge-shaped grid gaps are formed between the grids (the gap can be customized to 0.5~5mm). The wedge-shaped design makes the water flow pass through with less resistance and impurities are less likely to adhere, while ensuring interception accuracy.
- Slag cleaning system: It includes a rotating scraper and an auxiliary brush. The scraper moves along the inner surface of the grid, scraping the intercepted suspended solids (such as hair, fibers, and fine particles) to the top slag tank, and then discharges it through a screw conveyor.
- Driving device: It adopts low-noise reduction motor, with large output torque and stable operation, and can adapt to 24 hours of continuous operation.
- Control system: Equipped with a liquid level difference sensor. When the liquid level difference before and after the grid reaches the set value, the slag cleaning process will be automatically started to achieve unattended operation. It also supports remote monitoring and fault alarm.
Its modular structure design facilitates installation and maintenance, and individual grid plates can be replaced independently, significantly reducing later operation and maintenance costs.
2. Working Principle: Synergy of precise interception and efficient slag cleaning
The working process of the internal flow plate fine grille can be summarized as the four steps of "water inlet → interception → slag cleaning → slag discharge":
1. Water inlet stage: sewage enters the inside of the grid plate from the water inlet of the grid pool, and the water flow penetrates to the outside under pressure;
2. Interception stage: suspended solids and floating objects in the sewage are intercepted by the gaps in the grid and remain on the inside of the grid, while the clean water enters the subsequent treatment unit through the gaps;
3. Slag cleaning stage: As the intercepted impurities increase, the liquid level difference before and after the grid increases, and the control system triggers the slag cleaning device: the scraper plate rotates along the surface of the grid plate to scrape the attached impurities to the top slag tank;
4. Slag discharge stage: The impurities in the slag tank are transported to the press through a screw conveyor, dehydrated and transported out for processing.
The core advantage of this "internal flow" design is that impurities are always limited to the inside of the grid. When cleaning, the scraper plate directly contacts the impurities, which avoids the difficulty of cleaning the impurities on the outside of the traditional grid and effectively prevents clogging.
3. Core advantages: Performance breakthrough beyond traditional grilles
Compared with traditional equipment such as rotary grilles and rake-type grilles, internal flow plate fine grilles have the following significant advantages:
1. Ultra-high interception accuracy: The grid gap can be as small as 0.5mm, and the interception efficiency of SS (suspended solids) is as high as 95% or more. It can effectively remove hair, fibers, fine particles and other impurities that are difficult to capture with traditional grids;
2. Strong anti-clogging ability: The wedge-shaped grid seam and internal inflow design reduce the adhesion of impurities, and the slag cleaning process is thorough, making grid seam blockage less likely to occur and reducing the frequency of equipment shutdowns;
3. Compact structure and small footprint: The vertically installed grid assembly greatly saves space and is suitable for urban sewage treatment plants with limited land;
4. Low energy consumption and long life: Stainless steel material is corrosion-resistant, the drive system power is low (usually 0.5~2.2kW), and the operating cost is more than 20% lower than traditional grilles;
5. Easy maintenance: The modular grid can be quickly replaced, the slag cleaning system does not need to be frequently dismantled, and the operation and maintenance cycle is extended to more than half a year.
4. Application scenarios: covering preprocessing requirements in multiple fields
The internal flow plate type fine grille is widely used in various sewage treatment scenarios:
- Municipal sewage treatment plant: As a first-level pre-treatment equipment, it removes suspended solids, hair, plastic fragments, etc. in domestic sewage to reduce the load for subsequent biochemical treatment;
- Industrial wastewater treatment: Such as food processing (interception of food residues), printing and dyeing (interception of fiber), papermaking (interception of pulp) and other industries, targeted removal of industry-specific impurities;
- Reclaimed water plant: Provide pre-filtration for membrane treatment units (such as MBR) to prevent membrane components from clogging and extend membrane life;
- River management: used in sewage interception projects to intercept floating objects on the water surface and fine particles in the sediment to improve water quality.
For example, during the upgrade of a southern city's sewage treatment plant, after the use of internal inflow plate-type fine grilles, the effluent SS dropped from 120 mg/L to less than 40 mg/L, and the frequency of slag cleaning was reduced from twice a day to once every two days, saving about 150,000 yuan in annual operation and maintenance costs.
5. Future development: Upgrading direction of intelligence and greening
With the improvement of environmental protection requirements, internal flow plate fine grilles are developing in the direction of intelligence, modularization and multi-functionality:
- Intelligent monitoring: combined with Internet of Things technology to achieve real-time monitoring of equipment operating status, fault warning and remote control;
- Customized design: develop special grids (such as anti-corrosion coatings, special grid slit shapes) according to different wastewater characteristics;
- Co-processing: Integrated with the press and deodorization system to form an integrated pre-treatment unit to reduce floor space and secondary pollution.
Conclusion
As the "precision gatekeeper" at the front end of sewage treatment, the internal flow plate type fine grid has become the core equipment of the modern sewage treatment system with its high efficiency, stability and low consumption performance. It not only improves the accuracy and efficiency of the pretreatment process, but also facilitates the realization of wastewater resource utilization and provides key technical support for building a green and recycling water environment system. In the context of "double carbon" goals and water shortages, the application prospects of this fine grid will be even broader.
(The full text is about 1,100 words)
