[The formation of trihalomethanes precursor in anionic surfactant biodegradation].
Trihalomethanes (THMs) formed by chlorination of precursor substances in raw water, are found in drinking water. They are found at concentration levels higher than those of other organic contaminants. In the present study, the relationship between the formation of THM precursors and anionic surfectants biodegradation was investigated. Three anionic surfectants (LAS, AS and soap), dissolved in river
Chlorination of Organics in Drinking Water
Recently there has been great interest in the study of organic compounds in drinking water interest that stems largely from the results of a 1974 study of New Orleans drinking water, and the publicity that followed. 1 About the same time, two studies-"" called attention to the presence in finished drinking water of some trihalomethanes (mostly chloroform) which were not found in the respective raw waters at the locations of study. Both reports concluded that the trihalomethanes were formed during the Chlorination step of the water treatment process. The EPA undertook a survey of 80 selected cities to measure the concentrations of six halogenated compounds in raw and finished water. Those six included four trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane, bromoform) suspected of being formed during Chlorination, plus carbon tetrachloride and 1,2-dichloroethane, known contaminants at New Orleans, but not necessarily formed on Chlorination. During this National Organics Reconnaissance Survey (NORS) a more comprehensive organic analysis was also performed in five of the 80 cities and has just been completed in another five. The occurrence of trihalomethanes in finished drinking water was demonstrated to be widespread and a direct result of the
An Improved Method for Determining Organics by Activated Carbon Adsorption and Solvent Extraction—Part I
In the past, the expense and inconvenience of the available methods for measuring the general organic content of water using activated carbon adsorption and solvent extraction prevented many water-treatment-plant operators from measuring this important parameter in their finished water. The purpose of this investigation has been to provide the water-utility industry with a convenient, reliable procedure for measuring organics in water by this technique. This has been accomplished by developing a small, reliable, simpleto-operate sampler that passes about 60 1 of water (two-day sampling period) through 70.0 g of granular, coal-based activated carbon at a sampling rate of 20 ml/min (4.5-min contact time). The miniaturization of sampling equipment and the resultant reduction in equipment size for sample drying and extraction reduce the costs compared with previous carbonadsorption methods. The sample volume was chosen as a compromise and is satisfactory for most waters. As a companion to the sampler, a small extraction apparatus is used to extract the dried activated carbon with about 450 cycles of chloroform followed by about 450 cycles of 95 per cent ethyl alcohol. Although the elapsed times are two days for sampling, one day for adsorbent drying, five days for solvent extraction, and two-three days for extract drying, the number of actual man-hours required for the determination is less than six. The determination is called Organics-Carbon Adsorbable (O-CA). Field testing of the procedure has demonstrated that it meets the basic objectives and should be attractive to water-plant operators. Sampling of various types of waters showed that this technique can determine extract concentrations within a tenfold range in organic content between clean water and surface water heavily influenced by upstream discharges of wastes.