Trihalomethane Removal
TRIHALOMETHANES (THMs) – THE HEALTH RISKS & REMOVAL
Trihalomethanes (THMs) are a byproduct of the mixing of chlorine and organic materials naturally found in open, surface water supplies such as reservoirs. Therefore, exposure to THMs may occur from drinking tap water containing the chemical compounds. Also, exposure may occur from showering, bathing and other water use activities. For example, THMs can evaporate from the tap and be inhaled during showering, or they can be absorbed through the skin during bathing.
The U.S. Environmental Protection Agency (EPA) regulations give two choices for disinfectant residual in public water supplies: chlorine or chloramine. In following, many major water agencies are changing to chloramine to meet current and anticipated federal drinking water regulations. Since the Safe Drinking Water Act of 1974 and its amendments, utilities around the country have made changes to their disinfection strategies. Regulations have become more stringent for either microbial contaminants and disinfection byproducts (DBPs). Both chlorine and chloramine react with other compounds in the water to form DBPs.
Chlorine forms many byproducts, including trihalomethanes (THMs) and haloacetic acids (HAAs). Chloramine (a compound of chlorine and ammonia) forms a significantly lower amount of THMs and HAAs. NDMA (N-Nitrosodimethylamine, a classified carcinogen) forms when chloramine decays in water and releases ammonia through a process called nitrification. This converts to nitrosamines from ammonia-oxidizing bacteria.
FACTORS AFFECTING POTENTIAL DBP LEVELS
Regardless of the disinfectant used, the types and concentrations of DBPs typically vary from each utility. Factors include source water, level of organic matter, temperature, amount of disinfectant used and other variables. Chloramine will last longer in the distribution system than chlorine before dissipating. This means less is required for the residual to reach the last house than with chlorine. The result is less concentration at the front of the distribution system affecting taste and odor for those homes.
While the term “chloramine” is commonly used, the actual compound used is monochloramine. Monochloramine is a different chemical from dichloramine and trichloramine, which are chloramines formed by other complex chemical reactions. Dichloramine and trichloramine are sometimes found in and around indoor swimming pools and can cause skin, eye and respiratory problems. It often is formed when chlorine in the pool reacts with ammonia released from human bodies’ perspiration and other organic matter. For more information on chloramines and THMs, see our published article at https://www.wqpmag.com/water/chloramine.
For a link the Dighton Water District page for more information on the water, including annual reports, see https://www.dightonwaterdistrict.com/.
POTENTIAL HEALTH THREATS
Drinking water research indicates that certain (Disinfection By-products) DBPs have the potential to be harmful. Some research indicates that certain byproducts are linked to increases in cancer incidence, including bladder cancer. Other research indicates that certain DBPs can be linked to liver, kidney, central nervous system problems and reproductive effects. Anemia has also been linked. Scientists from many organizations have conducted research on the effects of DBPs. In some cases, research results are contradictory; some studies show links to adverse health effects and others do not. Regulatory documents describe the uncertainties in DBP risk assessments.
It is the job of regulators to weigh the public health benefits of disinfection against the risks of the potentially harmful DBPs. EPA sets limits for certain DBPs that are linked to the health effects previously described.
REMOVAL OF TRIHALOMETHANES FROM WATER
To remove THMs from your water supply in your home or business, the installation of a tank of activated carbon is the most effective and practical approach. The carbon is able to essentially trap the THMs until reaching maximum absorption. The carbon media inside the tank should be exchanged at regular intervals established by you and your water treatment professional. Reverse Osmosis is another technology that is effective in removing Trihalomethanes and a host of other contaminants. For more on this see the link at Reverse osmosis page.
Sediment & Carbon Filtration
REMOVING CHLORAMINE FROM WATER
Because the chloramine conversion reaction is catalytic in nature, activated carbons that exhibit enhanced catalytic activity are more efficient. The chloramine removal efficiencies of catalytic carbons cut required contact time, extend bed life and enable the use of smaller equipment. These advantages translate into cost savings for the end user without the sacrifice of the carbon’s capabilities. Also, NDMA has been shown to degrade relatively quickly when exposed to ultraviolet light.
