Ceramic and Activated Carbon Water Filters

Water filtering is the method of separating impurities from water and thus purifying it. Ceramic and activated carbon water filters are commonly used for the household water purifying purpose. They are very inexpensive and easy for maintenance. Though the working mechanism of the two is slightly different, the principle is same, that is blocking the impurities and allowing only water.

Ceramic Water Filters

Ceramic water filters are divided into two components, filter and the receptacle. The filter can be of two types, pot or candle. Candle is the most commonly used type of filter. The filter is seated on the top of the receptacle, which is fitted with a tap. The ceramic material is highly porous. Most impurities are larger than the pores of the ceramic filter. When the water is added in one side of the filter, everything except water molecules are blocked by the filters. Thus, the water becomes free of any impurities. The clean water is collected in the receptacle.

The impurities that accumulate in the top half or the filter region have to be removed timely, otherwise it may lead to the growth of algae and other micro-organisms. This can be done using soap solution with hot water and soft brush. These days, many ceramic water filters are treated with colloidal silver, which prevents the growth of bacteria and algae. Certain portable ceramic filters, like MSR Miniworks, require manual pumping for water filtering. The in-line ceramic filters are used for filtering the drinking water coming through the household plumbing.

The main problem with ceramic water filters is that it does not remove the chemical impurities. They are also prone to hairline cracking and chipping.

Activated Carbon Water Filters

Activated carbon is actually a charcoal that is processed to make it highly porous. Bituminous coal, lignite, wood, coconut shell are some of the materials used for making an active carbon. The extremely high porosity allows it to have a very high surface area. The surface area of 1 gram active carbon equals to around 500 m², which is 2.17 times that of a tennis court. The impurities of size 0.5 to 50 micrometers can be successfully removed by these filters. The chemical mechanism by which active carbon filters water is called adsorption. Active carbon shows hydrophobic and oleophilic properties, which means it shows repulsion to water and affinity for oil and such chemicals. Due to these properties, oil and other chemicals cling to the carbon filter, while water is allowed to pass through the pores.

Activated carbon filters are of two types, powdered block filters and granular activated filters. Block filters have an increased surface area, hence are more capable of filtering large number of impurities. Carbon filters are used mostly for household water purification, however they can also be used in municipal water treatment plants. Sometimes, they are also used as devices for reverse osmosis systems in pre-treatment stages. Carbon filters can be additionally treated with silver or KDF- 55 to restrict the growth of bacteria.

The problem with active carbon filters is that the impurities that cling to the filter tend to clog the pores, rendering the filter ineffective.

Both these filters are incapable of removing dissolved impurities or salts. Therefore they cannot be used where high quality purification is required. However, they are a cheap, easy to use and easy to maintain filters; hence, useful for small scale or household purification.