FAQs

A filter is a device or material designed to separate different substances from each other. In industrial processes, filtering typically falls into one of four main categories:

• Liquid from Liquid Separation
•  Solid from Liquid Separation
•  Solid from Solid Separation
•  Solid from Gas Separation

Sand filtration is a common and effective method for removing suspended solids from water. This process involves using multiple layers of sand with varying sizes and specific gravities. As water flows through the sand, suspended solids are trapped within the sand layers. When the filter becomes loaded with particles, the flow direction is reversed to clean the filter. Due to the possibility of smaller particles passing through, secondary filtration may be required for finer contaminants.

Water filters use various media to remove contaminants. Charcoal, or activated carbon, is often used in these filters. Unlike the ashy charcoal used in pencils, activated carbon in filters is granular or solid, which traps contaminants effectively. As water passes through, the carbon granules capture large impurities, similar to how river water filters through rocks. Modern filters often combine physical and chemical processes to enhance purification. For instance, carbon based media attract and bond with chlorine atoms, removing them from the water. Overall, water filters are designed to either block contaminants or chemically attract them, ensuring that the water remains clean.

A backwashing filter is a self cleaning water filter that periodically flushes out impurities. Unlike water softeners, which are ion exchangers, backwashing filters use a large tank filled with a filter medium. Water flows through the medium, removing impurities, and then exits the filter. When the filter becomes saturated, the system initiates a backwash cycle. This involves reversing the water flow through the medium to wash away collected dirt and recondition the filter for its next cycle.

If dirt is passing through your sand filter, it could be due to several issues:

•  A cracked or broken lateral.
•  A valve that needs servicing.
•  Air passing through the filter, causing channelling.

In such cases, it might be necessary to inspect and repair the filter system.

Generally, you should backwash your filter when the pressure increases by 10 psi over the initial startup pressure. For example, if the startup pressure is 15 psi, backwash when it reaches 25 psi. If the pressure does not return to the startup level after backwashing, it may be time to replace the sand.

To replace the sand in your top mount sand filter:

1. Disconnect the pipes from the valve on top of the filter.
2. Unscrew the valve counterclockwise.
3. Remove the old sand using a portable vacuum or scoop it out.
4. Fill the tank with water up to 2/3 full and then pour in the new sand. Avoid getting sand into the vertical pipe inside the tank.

Pressure Filter, Dual Media Filter, and Activated Carbon Filters:

Mode of Operation: Water flows down through the media and is collected from the bottom.

Service: Water enters from the top, flows downward, and exits from the bottom.

Backwash: Water flows upward through the media to clean it, generally performed every 24 hours or when pressure drop exceeds 8 psi.

Rinse: Water is introduced from the top and drained from the bottom.

Calculate vessel area based on volumetric flow rate and velocity.

 Determine vessel diameter using the formula: Diameter (m) = [Area (m²) / 0.7856] ¹/².

Suspended Silica: Can clog equipment, removed through coagulation, settling, and filtration.

 Color: Indicates organic matter, removed through coagulation, settling, and activated carbon filtration.

 Organic Matter: Can foul equipment, removed via coagulation, settling, filtration, and activated carbon.

 Bacteria: Can cause corrosion, removed through coagulation, filtration, UV, and chlorination.

 Iron: Causes red water and corrosion; removed through aeration, coagulation, and filtration.

 pH: High or low pH can induce corrosion; corrected by ion exchange or acid/alkali addition.

 Calcium and Magnesium (Hardness): Cause scaling, removed by ion exchange.

 Sulphate: Causes scaling; removed through ion exchange or reverse osmosis.

Filter media come in various types, including:

• Sand: Used for general filtration.
• Granular Activated Carbon (GAC): Effective for removing chemicals and odors.
• Anthracite: Used in multimedia filters for enhanced filtration.
•  Zeolite: Effective for removing ammonia and other contaminants.
•  Ion Exchange Resins: Used for softening water and removing specific ions.

The frequency of media replacement depends on several factors, including water quality, usage, and type of media. Regular backwashing and maintenance can extend the life of filter media. Generally, media should be replaced every 35 years, but consult your system’s manufacturer for specific recommendations.

Both activated carbon and granular activated carbon (GAC) are used to remove impurities through adsorption. The main difference is in their form: activated carbon is a broader term that includes various forms, while GAC refers specifically to the granulated form, which has a larger surface area for adsorption.

Dual media filters combine two types of media, typically anthracite and sand. The benefits include improved filtration efficiency, longer filter runs, and reduced need for frequent backwashing. The different media layers target various particle sizes and contaminants.

Choosing the right filter media depends on the specific contaminants in your water and the desired quality of treated water. For instance:

• Activated Carbon: Best for removing chlorine, volatile organic compounds, and odors.
•  Zeolite: Ideal for ammonia and heavy metal removal.
•  Sand: Suitable for general particulate removal.

A water quality test can help determine the most suitable media.

Water hardness is caused by high levels of calcium and magnesium. It can lead to scaling and reduced efficiency of household appliances. Treatment methods include ion exchange (water softeners) and the use of special filter media designed to remove hardness causing minerals.

Regular maintenance includes:

• Checking and replacing filter media as needed.
•  Cleaning or replacing prefilters and other components.
•  Backwashing or regenerating filters as required.
•  Inspecting for leaks and ensuring proper operation.

Consult your filter system’s manual for specific maintenance instructions.

Backwashing is a cleaning process where water is flowed in reverse through the filter media to remove accumulated dirt and debris. This process helps maintain filter efficiency and extend the lifespan of the filter media.

To improve efficiency:

• Ensure regular maintenance and timely media replacement.
•  Install prefilters to reduce the load on your main filter.
•  Optimize flow rates and pressure settings according to the manufacturer’s recommendations.

It depends on the specific requirements. For drinking water, you may need a filter designed to remove specific contaminants like chlorine or lead. Whole house filters generally handle larger volumes of water and may focus on particulate removal and general purification.

Pressure Filters: Use pressurized water to push through the filter media, suitable for high flow applications.

 Gravity Filters: Rely on gravity to pull water through the media, typically used for lower flow rates or in situations where pressurization is not feasible.

Low water pressure could be caused by:

• Clogged or dirty filter media.
•  A malfunctioning pump or control valve.
•  Blocked pipes or fittings.
• Check and clean the filter media, inspect the pump, and ensure all components are functioning correctly.

A multimedia filter contains layers of different media (e.g., anthracite, sand, and gravel) to provide a more thorough filtration process. It is used in applications where higher filtration efficiency is needed, such as in municipal water treatment or industrial processes.

Whole House Filter: Treats all water entering your home, ideal for comprehensive filtration needs.

 Point of Use Filter: Focuses on specific taps or appliances, suitable for addressing issues with drinking water or specific contaminants.

Consider your filtration needs and budget when making a decision.

Reverse osmosis (RO) is a filtration process that removes contaminants by pushing water through a semipermeable membrane. This membrane allows water molecules to pass through while blocking larger particles and contaminants. RO systems are highly effective for removing dissolved solids, salts, and other impurities.

The bed depth of filter media affects filtration efficiency and the capacity of the filter. To determine the appropriate bed depth:

Calculate the Required Flow Rate: Based on your application’s flow rate and the media’s velocity.

Refer to Media Specifications: Different media types have recommended bed depths.

To calculate the volume of filter media required:

• Determine the Filter Area: Measure the diameter of the filter vessel and calculate the surface area (Area = π × (Diameter/2)²).
• Determine Bed Depth: Based on media type and design guidelines.
• Calculate the Volume: Multiply the surface area by the bed depth (Volume = Area × Bed Depth).

For example, if your filter area is 1 m² and you need a bed depth of 0.5 m, the required volume is 0.5 m³ of media.

Flow rate is crucial for effective filtration and is typically expressed in gallons per minute (GPM) or cubic meters per hour (m³/hr). To calculate:

• Determine the Filter Area: Based on the filter’s dimensions.
• Choose the Appropriate Velocity: Refer to media specific velocity guidelines.
• Apply the Formula: Flow Rate = Area × Velocity. For instance, if your filter area is 2 m² and the recommended velocity is 10 m³/m²/hr, the flow rate would be 20 m³/hr.

Packaged Drinking Water: Water that has been purified and treated to meet safety standards for consumption. It is usually bottled in various sizes and is designed for convenience.

Bottled Water: Can include various types, such as spring water, mineral water, and purified water. The term “bottled water” encompasses all types of water sold in bottles, including both purified and naturally sourced waters.

The density of filter media influences its effectiveness and suitability for different applications:

• High Density Media: Often used for applications requiring robust filtration and longer lasting performance, such as granular activated carbon.
• Low Density Media: Typically used in less demanding applications and for lighter filtration tasks, like some types of sand.

Iron in water can cause staining and affect the taste and quality of your water. To remove iron, consider the following methods:

Oxidation and Filtration: Use an oxidation process, often with a chemical oxidizer like chlorine, followed by filtration through a media such as manganese greensand or manganese dioxide. This method converts dissolved iron into a solid form that can be easily filtered out.

Ion Exchange: This process involves using a water softener with a special resin to remove iron ions from the water. It is effective for low to moderate iron concentrations.

Chemical Injection: For high iron concentrations, injecting chemicals such as potassium permanganate or hydrogen peroxide into the water can help oxidize the iron, which is then filtered out.

 Aeration: Introducing air into the water can help oxidize dissolved iron, which can then be removed through filtration.

The choice of method depends on the concentration of iron in your water and specific treatment needs. It’s often useful to conduct a water test and consult with a water treatment professional to determine the most effective solution for your situation.

Activated carbon works by adsorbing impurities and contaminants from water. Its effectiveness comes from its large surface area and porous structure, which allows it to attract and hold onto molecules. As water passes through the activated carbon filter:

 Adsorption: Contaminants such as chlorine, volatile organic compounds (VOCs), and certain pesticides adhere to the carbon surface.

Chemical Reactions: Some contaminants may also undergo chemical reactions with the carbon, further reducing their concentration in the water.

Activated carbon filters are particularly effective at improving taste and odor while removing a range of organic contaminants. However, they may not be effective against all types of contaminants, such as heavy metals or microorganisms.