Contaminants Removal From Drinking Water By Activated Carbon (AC) Filtration and It’s Treatment Principles
We are very much concerned about the contaminants in water supply that may affect our health drastically and it may cause taste and odour problems. The water contaminants might include solvents, pesticides, industrial wastes, or contaminants from leaking underground storage tanks. Contaminants such as benzene, chlorobenzene, trichlorobenzenes, carbon tetra chloride and vinyl chloride in drinking water may pose very serious health risks even if they are present in very low level. Pesticides such as Atrazine can also pose a very serious health hazard.
Sometime drinking water can be disinfected with chlorine or chloramines. During disinfection the reaction of chlorine with organic matter can produce compounds such as trihalomethanes as byproducts and these byproducts may increase the risk of certain cancers.
Activated carbon (AC) filtration can effectively reduce some of these organic chemicals as well as certain harmless taste and odour producing compounds. AC filtration can be effective in removing chlorine, chloramines and some disinfection byproducts.
In addition lead from some older pipes and soldered joints may be may be present in water from some taps. AC filtration can reduce lead in drinking though another filter medium is commonly used in addition to AC filtration for this purpose. But only specialized AC filters effectively adsorb heavy metals. Radon, a radioactive decay product of od natural Uranium that can be related to lung cancer, can be found in ground water. Radon gas can also be removed by AC filtration.
There are two basic types of water filters 1. Sediment filters (or mechanical filters ) which filter particles by size and 2. Adsorptive (or reactive) filters which contain a medium that adsorbs or react with a water contaminant.
Activated carbon filtration is an adsorptive process in which the contaminant is attracted to and held (adsorbed) onto the surface of carbon particles. The efficiency of adsorption process is influenced by carbon characteristics (particle size, pore size, surface density and hardness and the contaminant characteristics (concentration, tendency of chemical to leave the water, solubility of contaminant and contaminant interaction to the carbon surface).
The carbon medium can be bituminous coal, anthracite coal, wood products, coconut shells or peanut shells. By activating the medium by steam or any other chemical without oxygen at high temperature, the carbon can acquire more surface area. More the surface area, greater the contaminant removal. In some cases, carbon also can be acid washed or impregnated with a compound to enhance the removal of specific contaminants. Also, greater contact time of water with the AC filters can increase the adsorption of contaminants.
To conclude, drinking water treatment using activated carbon (AC) filtration is an effective method for removing certain organic compounds, unpleasant tastes and odours and chlorine. An AC filtration system can be selected based on water analysis and assessment of individual user’s need and situation. Regular replacement of the filter/cartridge is critical to maintain the effectiveness and reduce bacterial contamination of the filter.