Chemicals Used in Treatment and Disinfection and Disinfection by-products
Constituent Occurrence
a. Contaminants from Treatment Chemicals
Acrylamide Residual acrylamide monomer occurs in the use of  anionic, cationic and non-ionic polyacrylamide coagulant aids;
Epichlorohydrin Epichlorohydrin is used for the manufacture of glycerol, unmodified epoxy resins and water treatment resins.
b. Disinfection Chemicals
Chlorine Residual Detected at the farthest point of the distribution system
Detected at any point in the distribution system
Iodine – – –
c. Disinfection by-products
Bromate As DBP, bromate is formed during ozonation when bromide ion is found in water or in concentrated hypochlorite solutions used to disinfect drinking water. The maximum level is based on the recent (2003) risk assessment as reported in WHO Guidelines (2004).
Chlorite The maximum values for chlorite and chlorate are provisional values. When chlorine dioxide is used as a disinfectant, chlorite or chlorate levels may be allowed to exceed the maximum level. Difficulty in meeting the maximum level is not a reason for compromising adequate disinfection.
Chlorate
Chloral hydrate (trichloroacetaldehyde) Chloral hydrate is formed as a by-product of chlorination when chlorine reacts with humic acids.
Dibromoacetonitrile Dibromoacetonitrile is produced during water chlorination from naturally occurring substances including algae, fulvic acid and proteinaceous material.
Dichloroacetic acid Chlorinated acetic acids are formed from organic material during water chlorination.
Dichloroacetonitrile Dichloroacetonitrile is produced during water chlorination from naturally occurring substances including algae, fulvic acid and proteinaceous material.
Formaldehyde Formaldehyde in drinking water results primarily from oxidation of natural organic matter during ozonation and chlorination.
Monochloroacetate Chlorinated acetic acids are formed from organic material during water chlorination.
Trichloroacetate Chlorinated acetic acids are formed from organic material during water chlorination.
2,4,6-trichlorophenol Chlorophenols are present in drinking water as a result of the chlorination of phenols, as by-products of hypochlorite with phenolic acid, as biocides or as degradation products of phenoxy herbicides.
Trihalomethanes
Bromoform Trihalomethanes are generated principally as by-products of chlorination of drinking water, being formed from naturally occurring organic compounds.

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