A pressure filter in a water treatment plant is a closed vessel containing a filtration medium, such as sand or activated carbon, used to remove suspended solids and other impurities from water under pressure. These filters act as polishing units, pretreatments, or tertiary treatment steps in various water treatment processes.
How Pressure Filters Work:
Pressure filters operate by forcing water through a filtration medium under pressure. This allows for a higher flow rate compared to gravity filters, making them suitable for applications where space is limited or higher capacity is required. Here's a breakdown:
- Influent: Water enters the filter under pressure.
- Filtration: The water passes through the filtration medium (e.g., sand, anthracite, activated carbon). Suspended solids and other impurities are trapped within the medium.
- Effluent: Filtered water exits the filter.
- Backwashing: Periodically, the filter is backwashed to remove accumulated solids. This involves reversing the flow of water through the filter bed to dislodge trapped particles.
Applications of Pressure Filters:
Pressure filters have diverse applications in water treatment, including:
- Industrial Water Treatment Polishing: Used as a final polishing step after physical-chemical treatment to ensure high-quality water for industrial processes.
- Drinking Water Pretreatment: Employed as a pretreatment step to remove turbidity and suspended solids before further treatment processes like disinfection or reverse osmosis.
- Domestic Wastewater Tertiary Treatment: Utilized as a tertiary treatment method for removing residual solids and pollutants from domestic wastewater, improving the quality of treated effluent.
Advantages of Pressure Filters:
- Higher flow rates: Can handle larger volumes of water compared to gravity filters.
- Smaller footprint: Occupy less space, making them ideal for compact treatment plants.
- Closed system: Minimizes contamination risks and odors.
- Versatile: Can be used with various filtration media to target specific contaminants.
Common Filtration Media:
| Filtration Media | Purpose |
|---|---|
| Sand | Removal of suspended solids, turbidity, and particulate matter. |
| Anthracite | Removal of larger particles; often used in combination with sand. |
| Activated Carbon | Removal of chlorine, organic compounds, taste, and odor. |
| Greensand | Removal of dissolved iron and manganese. |
| Multi-Media Filters | Combinations of media like sand, anthracite, and garnet for enhanced filtration |
In summary, pressure filters are enclosed filtration systems that efficiently remove suspended solids and impurities from water using various filtration media under pressure, serving as valuable components in diverse water treatment applications.
