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DRIVER-TREATMENT-WATER-INFRASTRUCTURE-CHEMISTRY-CHLORAMINE One new option that communities with ammonia problems have is biological filtration. This is a safe, chemical-free, method of removing ammonia. In a biological filtration facility, one of the stages of filtration is to pass the water through a special filter that is full of nitrifying bacteria. These bacteria take in the ammonia and some oxygen and perform a bio-oxidation reaction. They oxidize the ammonia into nitrite NH3 + O2 -> NO2- + 3H+ Then further oxidize that into nitrate, NO2- + H2O -> NO3- + 2H+. The bacteria gain energy from these reactions and are specialized to do them very efficiently. This process is part of the natural nitrogen cycle and does not produce any harmful byproducts. The nitrate that is produced by this process can easily be removed from the water by the reverse osmosis membrane in the final stage of the filtration process. The reaction between chlorine and ammonia can be written as NH3 +HOCl -> NH2Cl + H2O. In this chemical equation, NH3 is ammonia and HOCl is hypochlorous acid which is formed when the chlorine is first dissolved in the water. The primary result of this chemical reaction is NH2Cl, a chemical known as chloramine. Chloramine is a disinfectant like chlorine, it is a weaker disinfectant than chlorine but it lasts much longer in water. The chlorine concentration in water can gradually decrease as the chlorine evaporates out but chloramine does not do this. This makes it useful for making sure water stays disinfected throughout drinking water distribution systems. In areas where there is no, or very little, ammonia in the raw water treatment facilities might still want to use chloramine for this purpose. After chlorinating (disinfecting) the water, as the last step in the treatment process, they add ammonia and more chlorine to the water so that they react and create chloramine.

"Installing chlorine booster stations at strategic network locations or increasing the outlet disinfectant dose directly at the sources are among commonly used measures to increase disinfectant residuals throughout the network [29]. To test the network robustness to lower demand, the chlorine concentrations at the outlet of each of the three WTPs were increased to 2 mg/L. This allowed for investigating the potential of increasing chlorine dosage at the WTPs to compensate for the performance degradation under water conservation scenarios. "

DRIVERS-TREATMENT-TTHM-POLLUTION-SCARCITY-FUNDING Disinfection by-products (DBP) are a class of chemical by-products also referred to as trihalomethanes (THMs), formed when chlorine or bromine interacts with the natural organic materials found in water. DBPs also include other formed products, such as haloacetic acids, haloacetonitriles, haloketones, and chlorophenols. The composition and levels of specific DBPs are determined by water quality, water treatment conditions, and disinfectant type (IPCS, 2000). Primary sources of DBPs are chlorinated drinking water and recreational water bodies, such as swimming pools. In drinking water, trichloromethane is the predominant DBP, usually found at much higher levels than bromodichloromethane; tribromomethane is the least abundant (Krasner et al., 1989). DBPs are volatile at room temperature and can be detected in ambient air during activities such as showering, bathing, dishwashing, and swimming (Backer, et al., 2000; Gordon et al., 2006). Trichloromethane has industrial applications and is used to produce refrigerants and feedstock. It may be released into the environment where chlorine-based chemicals are used for bleaching and disinfecting processes or disposed at hazardous waste sites (IPCS, 2004; LaRegina, et al. 1986). Tribromomethane has limited industrial uses, mainly in geological assaying, electronics manufacturing, and as a solvent in laboratory analyses (ATSDR, 2005). DBPs tend not to bioaccumulate in aquatic organisms or persist in open or surface waters or soils, but they can remain in water within closed pipe systems. Workplace exposure may occur during the production of trichloromethane or tribromomethane, or in workplaces where DBPs may be generated, such as pulp or paper manufacturing, swimming pools, and water treatment plants (IPCS, 2004).

DRIVERS-POLLUTION-TREATMENT-SCARCITY-INFRASTRUCTURE Total trihalomethanes (TTHM) are a group of disinfection byproducts that form when chlorine compounds that are used to disinfect water react with other naturally occurring chemicals in the water. They are colorless, and will evaporate out of the water into the air. There are four significant TTHM potentially found in disinfected drinking water and their combined concentration is referred to as total TTHM. Levels of TTHM generally increase in the summer months due to the warmer temperatures, but can also be affected by seasonal changes in source water quality or by changing amounts of disinfection added. Water systems often can experience temporary increases in TTHM due to short-term increases in chlorine disinfection. Chlorine disinfection increases can occur when there is a water main break, when water systems are under repair, or when there is a potential microbial (example: bacteria) problem or threat.

Here are 12 critical facts about TTHM as the city's fight to reduce it continues: 1. Trihalomethanes are actually a group of four chemicals that are formed along with other disinfection byproducts when chlorine reacts with organic materials such as leaves or dirt in water, according to the U.S. Environmental Protection Agency. 2. TTHMs are odorless and colorless, according to the Michigan Department of Environmental Quality. That means the high levels of TTHM in Flint water last year are not related to problems such as discoloration and odor in tap water. 3. The four trihalomethane chemicals are chloroform, bromodichloromethane, dibromochloromethane and bromoform. 4. U.S. EPA regulates TTHM at a maximum allowable, annual, average level of 80 parts per billion. The standard has been in place since December 2001 for large public surface water systems and since December 2003 for small surface water and all groundwater systems. 5. Four of eight testing sites in Flint averaged more than the acceptable limit of 80 parts per billion of TTHM last year. 6. Testing for TTHM is done on a quarterly basis, which means that people who use the system are exposed to water for several months before public notice is required. That's because TTHM is a chronic -- not immediate --health threat, according to the DEQ. 7. U.S. EPA estimates the 80 parts per billion standard prevents an estimated 280 cases of bladder cancer each year out of a total of more than 330 million people who use public water supplies nationwide. 8. Since it started using the Flint River as its water source, three quarterly tests have produced these TTHM results in the city: 15 samples have been above the TTHM threshold. Nine samples have tested at less than 80 parts per billion. 9. The most recent quarterly test showed just one site of eight that was above the 80 parts per billion threshold. And a voluntary test of the same sites in late January by the city were all within were all within the limits. 10. The testin

"The present study found that approximately 63% of the hotels which were inspected following a Legionnaires' disease case notification were found to be colonized with Legionella spp. The study also evaluated the significant factors that contribute to the maintenance, management and disinfection of water distribution systems, including the successful implementation of WSPs to improve hotel water supply and sanitation systems. Chemical treatment and the monitoring of drinking water quality, including chlorine disinfection, pH adjustment, and water temperature control of hot water systems are recommended as control measures in water safety plans, in conjunction with other procedures. It has also been found that antiquated hotel buildings are at increased risk in terms of the safety and quality of the water in their distribution systems. To conclude, risk assessment, environmental monitoring and disinfection of water systems, as well as the implementation of preventive control measures (WSPs) are the key elements for preventing contamination by pathogenic microorganisms in large public and private water distribution systems."

DRIVER-TTHMs-POLLUTION-PURITY-INFRASTRUCTURE-TREATMENT Trihalomethanes (THMs) are the result of a reaction between the chlorine used for disinfecting tap water and natural organic matter in the water. At elevated levels, THMs have been associated with negative health effects such as cancer and adverse reproductive outcomes. Now a study by government and academic researchers adds to previous evidence that dermal absorption and inhalation of THMs associated with everyday tap water use can result in significantly higher blood THM concentrations than simply drinking the water does [EHP 113:863-870]. The results of this exposure assessment study could serve as a guide for future epidemiologic investigations exploring the potential connection between THMs in tap water and adverse health effects.

DRIVER-FLINT-TREATMENT-WATER-POLLUTION-CHEMISTRY Former EPA Drinking Water Standards Director, Dr. Joseph Cotruvo developed the US Environmental Protection Agency's (EPA's) first THM Rule in 1979. I spoke with him for his perspective on TTHM in Flint's drinking water: "Scientists have studied the health effects of disinfection byproducts extensively. For example, the January 4, 2006 Federal Register,2 which announced the Stage 2 Rule, cites over 60 mixed result research studies probing the potential health effects of exposure to disinfection byproducts such as TTHM. After reviewing many studies, the Agency concluded that 'no dose response relationship or causal link has been established between exposure to chlorinated drinking water or disinfection byproducts and adverse developmental or reproductive effects.' Nevertheless, EPA takes a very precautious stand, saying the studies 'do provide an indication of a potential health concern that warrants incremental regulatory action beyond Stage 1 DBPR [Disinfectants and Disinfection Byproducts Rule].'"

DRIVER-WATER TREATMENT TECHNOLOGY Ozone water treatment oxidizes iron, manganese, and sulfur in your well water to form insoluble metal oxides or elemental sulfur. These insoluble particles such as rust, are then removed by filtration which is typically activated carbon, manganese dioxide, or other media such as filter sand. Ozone is much faster at killing bacteria and oxidizing iron and manganese compared to chlorine or peroxide. One advantage for home use is that ozone is quite unstable and will degrade over a time frame ranging from a few seconds to 30 minutes.