How Water Filters Work – 2: Ceramic Filters and Reverse Osmosis Filter Systems

Ceramic Filters

Ceramic filters work really well against bacteria, sediments and parasites that are present in water. Some models of ceramic filters can filter up to 0.9 of a micron. This type of filter has a hollow core made of ceramic that can be cleaned easily by scrubbing it with soft brush or scotch brite sponge. A ceramic filter can also be used as a sediment pre-filter in replacement of a standard pleated filter or foam and string wound. Some ceramic filters can also be fitted with an additional activated carbon block core to help increase the efficiency of their taste and odour reduction efficiency.

Sediment Filters

Sediment filters are also known as particulate filters, they function as fine sieves or strainers which trap and as a result reduce the amount of dirt and other foreign particles present in water. Using sediment filters as a pre-filter protects a water purifier from damage and deterioration, as it takes longer for it to become clogged with unwanted medium. Sediment drain filter basically have two types of ratings; coarse and fine. Sediment filters can be manufactured from wound string and rigid foam or pleated film. These types of filters work best when mounted under the sink. The life of a common sediment filter basically depends on the pollutants or rubbish present in the water that it filters, however their average life span ranges from 6 to 12 months.

Reverse Osmosis Purifiers

As the name clearly indicates a reverse osmosis purifier basically operates on the principle of osmosis. Osmosis is a process which happens when 2 solutions made up of different concentrations are separated through a semi-permeable membrane. Similarly, a reverse osmosis purifier works by forcing the water under great pressure against an ultrafine semi-permeable membrane which is especially designed to allow single water molecules to pass through, while at the same time not allowing pollutants or contaminants to permeate through. Thus, the membrane essentially functions as a mechanical filter that strains out microorganisms, asbestos, particulate matter and even individual molecules of heavier organic compounds.

A typical construction of a reverse osmosis purifier is that it consists of four filters in a series along with a storage tank. The 1st filter in the series is a sediment filter, the 2nd is a carbon block, the 3rd is a membrane while the 4th is an activated carbon block to remove any left behind chlorine by-products. This type of purifier usually produces water at a relatively slow rate- almost drop by drop. The reverse osmosis purifier can be directly attached to the faucet and can be used to fill a glass or a bottle directly from the purifier. An average purifier produces around 200 litres of water per day which is sufficient for an average small family. Unlike normal filters, reverse osmosis purifiers don’t actually accumulate pollutants but the membranes on their own gradually degrade with use. The membranes should preferably be changed around every 3-5 years or as explicitly specified by the purifier’s manufacturers.

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