In the sewage treatment process chain, pretreatment is a key link that determines the efficiency of subsequent links. As the core equipment in the pretreatment stage, the inflow grille has become an indispensable "gatekeeper" in modern sewage treatment plants and industrial wastewater treatment systems due to its high-efficiency interception, low blockage, and intelligence. Through innovative structural design, it accurately intercepts suspended solids, floating objects and other impurities in sewage, clearing obstacles for subsequent biological treatment, deep purification and other processes.
1. Structure and working principle: filtering logic from inside to outside
The internal inflow grille usually adopts a rotating drum structure, which is mainly composed of a grating drum, a driving system, a flushing device, a slag discharge system and a control system. Its core design lies in the water flow direction of "inward flow and outer flow":
- Water inlet stage: Sewage enters from inside the drum and penetrates outward through the gaps between the bars. At this time, suspended matter in the water (such as plastic bags, fibers, hair, sediment, etc.) is trapped inside the drum and cannot pass through the grating gap;
- Impurity removal: As the drum rotates slowly (the rotation speed is usually 0.5-2r/min), the trapped impurities are brought to the top and peeled off by high-pressure flushing water or a scraper device;
- Slag discharge and water discharge: The stripped screen slag is discharged through a screw conveyor or belt conveyor, and the purified water flows out from the outside of the drum and enters the subsequent processing unit.
The grid gap can be adjusted according to processing needs (commonly 0.5-10mm). The materials are mostly stainless steel or high-strength engineering plastics, which are corrosion-resistant and have a long service life. The control system adopts PLC intelligent control, which can realize automatic start and stop, backwash, fault alarm and other functions, reducing the cost of manual intervention.
2. Core features: efficient, stable, low maintenance
Compared with traditional grilles (such as rotary grilles and rake grilles), the advantages of internal flow grilles are reflected in the following aspects:
1. Efficient interception: The internal inflow design concentrates impurities on the inside of the drum, avoiding the penetration of impurities caused by the impact of water flow. The interception rate can reach more than 90%, which is much higher than the 80% of traditional grilles;
2. Low risk of clogging: When water flows from the inside to the outside, the gaps between the bars are not easily blocked by impurities, reducing the need for frequent cleaning. Even if there is a slight blockage, the high-pressure flushing system can quickly clear it;
3. Compact footprint: The drum can be installed vertically or tilted, and has a compact structure. The footprint is only 1/3-1/2 of that of a traditional grille, making it suitable for sewage treatment plants with limited space;
4. Low energy consumption and noise: The drum rotates slowly, the driving motor power is small (usually 1.5-5kW), and the operating noise is less than 60dB, which meets the requirements of urban environment;
5. Intelligent operation and maintenance: Equipped with sensors to monitor screen slag volume, operating temperature, motor current and other parameters, the equipment status can be remotely monitored and unattended.
3. Application scenarios: covering municipal and industrial fields
The internal inflow grille has strong adaptability and is widely used in various sewage treatment scenarios:
- Municipal sewage treatment plant: As the first level of pretreatment, it intercepts impurities such as plastic bags, paper towels, and fibers in domestic sewage and protects subsequent water pumps, aeration tanks and other equipment;
- Industrial wastewater treatment: Effectively reduce the SS (suspended solids) concentration of wastewater in industries such as food processing (removing raw material residues and grease), papermaking (intercepting pulp fibers), printing and dyeing (removing cloth debris), slaughtering (intercepting animal hair and visceral residues);
- Pumping station pretreatment: installed at the entrance of urban drainage pumping stations to prevent impurities from clogging the water pump impeller and reduce equipment failures;
- River management: used in black and smelly water treatment projects to intercept floating objects on the water surface and solid impurities in the sediment to improve the fluidity of the water body.
4. Technological Innovation and Future Trends
With the improvement of environmental protection requirements, inlet flow grilles are developing in a smarter and more efficient direction:
- Intelligent upgrade: Combined with Internet of Things technology, it can realize real-time upload and analysis of equipment operating data, predict maintenance needs, and reduce downtime;
- Material optimization: Use new wear-resistant and corrosion-resistant materials (such as silicon carbide coating) to extend the life of the equipment;
- Modular design: Multiple devices can be flexibly combined according to the processing capacity to adapt to the needs of projects of different sizes;
- Energy-saving transformation: By optimizing the drum structure and flushing system, energy consumption is further reduced, in line with the "double carbon" goal.
For example, after a coastal city sewage treatment plant adopted an intelligent inflow grille, the screen slag removal rate increased to 95%, and the equipment maintenance frequency was reduced from 3 times a month to 1 time per quarter, saving approximately 200,000 yuan in annual operation and maintenance costs, and reducing the load pressure of subsequent processes.
Conclusion
As a key equipment at the front end of sewage treatment, the inflow grille not only improves the pretreatment efficiency, but also ensures the stable operation of the entire treatment system. Under the concept of "lucid waters and lush mountains are invaluable assets", it will continue to play an important role in promoting the utilization of sewage resources and improving the ecological environment. In the future, with the continuous iteration of technology, inflow grilles will become an indispensable part of the smart water system, contributing to the construction of a green and sustainable water environment.
(The full text is about 1050 words)
