filtration
Technologies - Filtration
Used to produce drinking or process water, filtration water treatment processes ground, surface or wastewater using many technologies. These include fine mesh screening, media filtration and membrane filtration. Each method effectively separates solids from water.
What Is Filtration Water Treatment?
Filtration is a separation process where a solid-liquid mixture is percolated through a porous medium (filter) which ideally screens out solid particles, letting the liquid (filtrate) through. We mainly have in-depth filtration (filtration through a granular bed) and filtration accompanied by the formation of a cake (filtration ‘through a support’). This sub-section regroups all mechanisms and laws governing filtration, means used for monitoring and controlling a cycle, and the various wash systems. Please refer to filters for a description of the main filters.
Many industries need a constant stream of portable drinking or process water. For example, operations such as food manufacturing and automotive assembly uses process water, whilst sewerage treatment plants require effective wastewater filtration processes.
Using filtration in water treatment, solid particles are entirely removed from the water. This can be from ground water, surface water or even pre-treated wastewater.
These processes in water treatment have a clear objective: to provide the correct quality of water for the specific industrial application.
The Filtration Water Treatment Process
Filtration is an important stage when treating water. Firstly, multiple methods of pre-treatment are common. This could include flocculation, coagulation and sedimentation.
Following pre-treatment, various forms of water filtration can be used. For fine screening, drumfilters and discfilters are common. They remove suspended solids from the water and polish effluent from wastewater treatment plants.
Should media filtration be chosen, pressure gravitational filters can be used. These work by the media forming a barrier to the passage of suspended solids, absorbing some compounds contained in the liquids.
Finally, membrane technologies can be used. These include ultrafiltration, microfiltration, nanofiltration, and reverse osmosis. They will retain different sizes of particles and ions, whilst allowing pure water to flow through.
It is also wise to use water filter cartridges. Acting as protection barriers, they retain solids and particles upstream.
Types Of Water Filters
Multimedia
Pressure vessels with sand or other loose media are widely used in industrial filtration applications. During the cleaning cycle, called “backwash”, the bed is lifted (or “fluidized”) to loosen the filter media and release trapped dirt which is removed in the backwash flow. After the backwash cycle, the bed is allowed to settle before the filter is returned to service (i.e., normal flow). A “filter-to-waste” cycle is used following the settling to assure the filtration media has sufficiently re-stratified and that any loose dirt is removed from the underdrain / collectors.
Multimedia filtration refers to a pressure filter vessel which utilizes three or more different media as opposed to a “sand filter” that typically uses one grade of sand alone as the filtration media. In a single media filter, during the “settling” cycle, the finest or smallest media particles remain on top of the media bed while the larger, and heavier particles, stratify proportional to their mass lower in the filter. This results in very limited use of the media depth since virtually all filterable particles are trapped at the very top of the filter bed or within 1-2 inches of the top where the filter media particles have the least space between them. The filter run times are thus very short before the filter “blinds” or develops so much head pressure that it must be backwashed to avoid seriously impeding or stopping the flow.
Multi-media water filters typically utilize three layers of media for multimedia filtration: anthracite, sand and garnet. These media are often chosen for use in multimedia filters due to the distinct differences in their densities. Anthracite is the lightest filtration media per unit volume, followed by sand, and then garnet.
The idea behind using media with differing masses is that during backwashing the lightest media with the largest particles (anthracite) will naturally stratify at the top of the filter, while the intermediate sized media (sand) will settle in the middle, and the heaviest media with the smallest particles (garnet) will settle to the bottom.
ACTIVATED CARBON
Good for removal of chlorine, chloroform, agricultural chemicals, organic substances, sediment, and magnesium.
Activated CarbonThe key to understanding how activated carbon works is adsorption. As opposed to absorption, in which one material will take in or soak up another material, adsorption occurs when one material sticks to another while passing through. This is the basis of activated charcoal or activated carbon.
Activated charcoal is created when organic material with high carbon content (like wood, coal, or coconut shells) is heated in such a way that it does not burn, but instead results in char. The char is then treated to create a porous material that binds to certain toxins and impurities, thus pulling them out of the water flowing through the system.
This is the most common type of filter and often used in conjunction with other filtration methods for maximum toxin removal.
ION EXCHANGE
Good for removal of hard water and radioactive material.Ion Exchange
As the name suggests, ion exchange filters consist of a substance that will exchange one ion for another as water flows through it. For example, ion exchange will replace calcium or magnesium ions, which cause water hardness, with sodium ions. This will “soften” the water. A home may be experiencing hard water if its water leaves stains on washed dishes. Hard water tends to build up in pipes, which may decrease the life of certain kitchen appliances.
Although ion exchange helps with hard water and some radioactive material, the filter does not remove organic material, particles, or bacteria as effectively as other filtration options.
Filter Housing
A Filter Housing is a casing around filter Cartridges or Bags or Basket. Filter Housings are available in different sizes and styles. The design of Filter Housing is dependent on the following factors:
How Does It Work
The Fluid enters through Inlet nozzle of the housing which directs the flow to the filter cartridge or bag put inside. The filter cartridge or bag separates the contaminants from the fluid. After this process, the clear fluid comes out from the outlet nozzle.
Different Types Of Filter Housing
Applications Of Filter Housing
Water Treatment
RO Prefiltration
Oil and Gas
Refineries
Pharmaceutical
Chemical
Paints
Water Treatment
Food and Dairy Beverages
Dyes and Intermediates
Honey
Process Industries
Power Plants
Textile