mechanical filter

• Product Overview

The mechanical filter (also known as pressure filter or multi-media filter) is a versatile water treatment system developed by our company, operating on the principle of deep filtration. This equipment fills a pressurized chamber with specific granular media (e.g., quartz sand, anthracite, activated carbon) to physically intercept and remove impurities such as suspended solids, silt, colloids, certain organic compounds, and iron/manganese oxides. It delivers qualified feed water for subsequent processes or serves as a final safeguard to meet effluent turbidity standards. As a pre-treatment or purification device, it features a reliable structure and mature operational management.

• Structure and Working Principle

1. Core structural composition

The equipment consists of vertical or horizontal cylindrical pressure steel vessels, primarily comprising:

• Tank structure: The main body is typically constructed with corrosion-resistant carbon steel, stainless steel (SS304/316L), or fiberglass reinforced plastic (FRP), designed to withstand the system's working pressure.
• Filter media layer: The core functional section. Depending on the treatment objective, one or multiple layers of filter media with different particle sizes and densities can be filled. Common combinations include:

• Double-layer filter media: upper layer anthracite, lower layer quartz sand.
• Multilayer filter media: may include activated carbon, magnetite, garnet, etc.
  • Water distribution and collection system:
• Upper water distribution/counterwash drainage device: ensures uniform water distribution and serves as the drainage outlet during counterwashing.
• Bottom collection/reverse washing water distribution device: Collects clean water during filtration and evenly distributes rinse water during reverse washing. Common configurations include dome plates with filter caps, filter tubes, or water distributors.
  • Pipeline and valve system: includes inlet valve, outlet valve, backwash inlet valve, backwash drain valve, forward wash valve, and exhaust valve, etc., used to achieve filtration, backwash, forward wash, and other operational processes, which can be manually or automatically controlled.
  • Monitoring instruments (optional): Pressure gauges and differential pressure gauges are used to monitor operational status.

2. Working Principle

The device periodically switches between filtration and backwash states.

• Filtering state: Raw water flows downward (or upward) through the filter media layer under pressure. Impurities in the water are retained and adsorbed by the surface and internal pores of the filter media. Clean water is collected and discharged through the bottom collection system.
• Backwashing condition: When the filter bed resistance (pressure differential) increases or effluent quality deteriorates after prolonged operation, backwashing is required. Water flows upward through the filter layer at high speed, causing the filter media to expand and become fluidized. Through hydraulic shearing and friction between media particles, retained impurities are dislodged and discharged with the backwash water, thereby restoring the filter media's filtration capacity. Post-backwashing, a brief forward wash is typically performed to remove residual wastewater.
• Core Technical Features

1. Deep filtration with high rejection capacity: By utilizing the pore gradient formed by filter media of different particle sizes, it achieves stepwise retention of impurities from large to small. The filter layer can accommodate more impurities in the depth direction, resulting in a relatively longer operational cycle.
2. The filtration effect is relatively stable: the reasonable design of filter material gradation and sufficient filter layer thickness help to maintain the relative stability of effluent water quality and have a certain buffering ability for inlet turbidity fluctuation.
3. The backwashing regeneration demonstrates excellent performance: A well-designed backwashing system (with optional air-assisted cleaning) effectively restores filter media properties and ensures sustained filtration efficiency.
4. The operation and maintenance are relatively mature and simple: the process flow is classic, the automation control scheme is mature, and the daily maintenance mainly revolves around periodic backwashing, which is easy for operators to master.
5. The system offers flexible application and scalable functionality: By selecting different filter media combinations (e.g., quartz sand for turbidity removal, activated carbon for organic matter and chlorine removal, manganese sand for iron and manganese removal), the equipment can be adapted to various primary treatment objectives.

• Main technical parameters

• Typical Application Fields

As a core pretreatment or purification unit in water treatment systems, this equipment has extensive applications:

• Industrial water treatment: bypass filtration or makeup water treatment for industrial circulating cooling water systems; pretreatment (turbidity removal) of boiler feedwater and process water.
• Urban water treatment: filtration units in small-scale waterworks for villages, towns, and residential areas; conventional or advanced pretreatment in municipal waterworks.
• Wastewater Treatment and Reuse: Pretreatment in advanced treatment processes for industrial wastewater or municipal sewage (to protect subsequent membrane systems) or tertiary treatment (to further reduce SS).
• Specific pollutant removal: Equipment using activated carbon filter media is employed for chlorine removal, decolorization, and organic matter removal; equipment utilizing manganese sand filter media is used for iron and manganese removal in groundwater.
• Seawater desalination pretreatment: As a critical pretreatment step before the reverse osmosis system, it removes suspended solids and colloids.