In the urban sewage treatment system, the pretreatment link is the first level to ensure the stable operation of the subsequent process, and the grid equipment is the core of this level. Although traditional grilles such as artificial grilles and mechanical grilles can intercept large suspended particles, they have problems such as low interception efficiency, easy clogging, and high maintenance costs. As a new type of high-efficiency pretreatment equipment, the internal inflow grille has gradually become the "new favorite" of sewage treatment plants due to its unique structural design and excellent performance.
1. The structure and working principle of the inflow grille
The internal inflow grille usually adopts a drum structure, and the core component is a cylindrical filter drum. Sewage enters axially from the inside of the drum and flows out through the filter under the action of water pressure, while suspended solids and floating objects (such as plastic bags, fibers, hair, etc.) are trapped on the inner wall of the drum. As the drum rotates slowly, the intercepted impurities are brought to the top, where they are peeled off from the filter screen by high-pressure flushing water or a scraper device, fall into the collection tank below, and are finally discharged by a screw conveyor.
Compared with the traditional external inflow grille (sewage flows in from the outside of the drum), the advantage of the internal inflow design is that impurities are concentrated inside the drum, avoiding impurity adhesion and blockage caused by external water flow impact; high-pressure flushing water acts on the filter screen from the outside, which can clean impurities more thoroughly without damaging the filter screen structure.
2. Core advantages of internal inflow grille
1. Efficient interception and fine filtering
The filter aperture of the internal inflow grille can be selected according to needs (usually 0.5mm-5mm), which can effectively intercept small suspended solids, and the interception efficiency can reach more than 90%. For example, for difficult-to-treat impurities such as hair and fibers in municipal sewage, its interception effect is far better than that of traditional grilles, reducing the load on subsequent processes (such as aeration tanks and membrane treatment).
2. Low energy consumption, stable operation
The drum rotates at a low speed (usually 1-5 rpm), the motor power is small (usually 1.5-5kW), and the energy consumption is only 1/3 of a traditional grille. At the same time, the internal inflow design makes the water flow resistance small, the equipment operation noise is low, and the failure rate is greatly reduced.
3. Easy maintenance and controllable costs
Impurities are concentrated inside the drum, and there is no need to disassemble the filter when cleaning. Just check the flushing system and scraper regularly. Some intelligent inlet grilles are also equipped with clogging monitoring sensors. When the filter resistance exceeds the threshold, the drum speed will be automatically increased or the flushing intensity will be enhanced to achieve unattended operation.
4. Small footprint and strong adaptability
The rotary drum type has a compact structure and covers only about half the area of a traditional grate, making it suitable for sewage treatment plants with limited space. In addition, most of its materials are stainless steel or corrosion-resistant alloys, which can adapt to high-salt, high-acid-alkali industrial wastewater environments.
3. Application scenarios and actual cases
Inlet flow grilles are widely used in the following scenarios:
- Municipal sewage treatment plant: as water inlet pre-treatment equipment, intercepting floating and suspended solids, and protecting follow-up equipment such as water pumps and aeration tanks;
- Industrial wastewater treatment: such as food processing, textile, papermaking and other industries, intercepting fibers, residues and other impurities;
- Pumping stations and river management: used in pumping station water inlets or river sewage interception projects to reduce garbage entering the water body;
- Hospital sewage: intercept medical waste (such as cotton swabs, gauze) to prevent contamination of subsequent treatment systems.
Case: A southern urban sewage treatment plant originally used traditional mechanical grilles, which required manual cleaning three times a day, with an interception efficiency of about 70%, resulting in the accumulation of scum in the subsequent aeration tank. After replacing the inflow grille, the interception efficiency increased to 92%, and only one inspection was required per day. The equipment failure rate dropped by 40%, saving approximately 120,000 yuan in annual maintenance costs. At the same time, the membrane fouling rate of the subsequent membrane bioreactor (MBR) was reduced by 25%, extending the service life of the membrane components.
4. Technological Innovation and Future Trends
With the improvement of environmental protection requirements, inlet flow grilles are developing in the direction of intelligence and modularization:
- Intelligent monitoring: Integrate Internet of Things technology to monitor filter resistance, flushing water volume, motor current and other parameters in real time, and remotely control through the cloud platform;
- Modular design: Multiple drum units can be flexibly combined according to the volume of treated water to adapt to different scales of sewage treatment needs;
- Green materials: Use degradable filters or nano-coating technology to further improve filtration efficiency and anti-clogging capabilities.
Conclusion
As the "efficient gatekeeper" at the front end of sewage treatment, the inflow grille not only solves the pain points of traditional grilles, but also provides guarantee for the stable operation of subsequent processes. Under the "double carbon" goal, its low energy consumption and high efficiency will help the sewage treatment industry achieve energy conservation and consumption reduction. In the future, with the continuous innovation of technology, inlet flow grilles will play an important role in more fields and become one of the key equipment to promote water environment management.
(The full text is about 1050 words)
