Formation Mechanism and Chemical Safety of Nonintentional Chemical Substances Present in Chlorinated Drinking Water and Wastewater

Abstract

This paper reviews the formation mechanism and chemical safety of nonintentional chemical substances (NICS) present in chlorine-treated water containing organic contaminants. Undesirable compounds, i.e., NICS, may be formed under certain conditions when chlorine reacts with organic matter. The rate and extent of chlorine consumption with organics are strongly dependent on their chemical structures, particularly whether double bonds or sulfur and nitrogen atoms occur in the molecules. Organothiophosphorus pesticides (P＝S type) are easily oxidized to their phosphorus compounds (P＝O type) in chlorinated water containing HOCl as little as 0.5 mg/l, resulting in an increase in cholinesterase-inhibitory activity. Chlorination of phenols in water also produces a series of highly chlorinated compounds, including chlorophenols, chloroquinones, chlorinated carboxylic acids, and polychlorinated phenoxyphenols (PCPPs). In some of these chloroquinones, 2,6-dichloroalkylsemiquinones exhibit a strong mutagenic response as do positive controls used in the Ames test. 2-Phenoxyphenols in these PCPPs are particularly interesting, as they are present in the chlorine-treated phenol solution and they are also precursors (predioxins) of the highly toxic chlorinated dioxins. Polynuclear aromatic hydrocarbons (PAHs) were found to undergo chemical changes due to hypochlorite reactions to give chloro-substituted PAHs, oxygenated (quinones) and hydroxylated (phenols) compounds, but they exhibit a lower mutagenic response. In addition,ˆeld work was performed in river water and drinking water to obtain information on chemical distribution and their safety, and the results are compared with those obtained in the model chlorination experiments.

Sorption of Aromatic Compounds with Copolymer Sorbent Materials Containing β-Cyclodextrin

“…The buildup and transport of chlorophenol-based pollutants (e.g., biocides, petrochemicals, and pharmaceuticals) represent an important environmental issue which may adversely impact aquatic ecosystems, biodiversity, and human health [3,4,5,6,7,8]. One of the eight millennium goals of the United Nations Environment Program (UNEP) is the provision of clean drinking water and its mandate is to reduce the proportion of people without sustainable access to safe drinking water by half in 2015 [9].…”

Temperature and Concentration Effects on Biodegradation Kinetics and Surface Properties of Phenol Degrading Rhodotorula glutinis

“…Moreover, phenolic compounds in drinking water cause taste and odor problems at very low concentrations (~2 µg/L) and can form toxic polychlorinated phenols after chlorination [2].…”

“…Most of the phenol removal studies in the literature are focused on bacterial biodegradation [1][2][3][4][5][6][7][8][9][10][11][12] and there is limited information on the phenol metabolization by the yeasts. Furthermore, little is known about the biodegradability of phenol by yeasts at colder temperatures [13,14] which is more significant for in-situ applications, compared to mesophilic temperatures [15].…”

Effect of hypochlorite oxidation on cholinesterase-inhibition assay of acetonitrile extracts from fruits and vegetables for monitoring traces of organophosphate pesticides

“…In order to provide greater insight into the possible role of organic compounds in the formation of chlorinesubstituted or chlorine-oxidised compounds and chlorineinduced mutagens, our laboratory has further explored the study of the aqueous chlorination chemistry of organic compounds (Onodera, 2010;Kanno et al, 2010Kanno et al, , 2012. In the present study, we studied the chlorination conditions of the anti-cholinesterase inhibitors, organophosphothionate and carbamate pesticides in the acetonitrile extracts of fruits and vegetables, and developed a combination method of hypochlorite oxidation and ChE-inhibiting assays to monitor traces of these contaminants in apple, tomato, cucumber and strawberry.…”