The classification and functions of filter media are as follows:
Classification of Filter Media:
Filter media can be broadly classified into two main categories based on their material composition: inorganic filter media and organic filter media.
Inorganic Filter Media:
These include natural minerals such as gravel, garnet, maifan stone, zeolite, etc.
Coal-based materials like anthracite coal are also commonly used.
Metals and alloys, though less common, can also be used as filter media.
Ceramic materials like expanded clay aggregates (ECA) and ceramic foam filters are increasingly popular due to their durability and efficiency.
Siliceous materials like quartz sand are widely used in water filtration systems.
Other inorganic materials like rare earth ceramic sand, magnetite, and nutshells also find specific applications.
Organic Filter Media:
These include natural organic materials like decomposed plant matter, peat moss, and coconut husk fibers.
Synthetic polymers like polypropylene, polyester, and nylon are also used to make filter media with specific properties.
Functions of Filter Media:
Removal of Impurities: Filter media are designed to remove suspended solids, colloids, bacteria, viruses, and other contaminants from water or air, improving their quality.
Particulate Filtration: By creating a physical barrier, filter media trap and retain particles larger than the pore size of the media, effectively removing them from the fluid stream.
Adsorption and Absorption: Some filter media, like activated carbon, have a high surface area that allows them to adsorb organic compounds, gases, and odors from fluids.
Chemical Reaction and Ion Exchange: Certain filter media can remove specific contaminants through chemical reactions or ion exchange processes, such as the removal of heavy metals or hardness minerals.
Biological Filtration: In biological filters, media provides a surface for the growth of beneficial microorganisms that break down organic matter and other pollutants.
Protection of Downstream Equipment: By removing contaminants upstream, filter media protect downstream equipment from fouling, corrosion, and premature wear.
Enhancement of Water Quality: In some cases, filter media can also improve the taste, odor, and overall quality of water by adding beneficial minerals or removing undesirable compounds.
In summary, filter media play a crucial role in purifying water and air by removing impurities, enhancing quality, and protecting downstream equipment. The choice of filter media depends on the specific application, contaminant load, and desired treatment outcomes.