Only 5%-10% of the nonvolatile organic compounds that comprise the remaining 90% of the total organic matter have been identified. Approximately 90% of the volatile organic compounds that can be analyzed by gas chromatography have been analyzed, but this represents no more than 10% by weight of the total organic material. ![]() These compounds make up only a small fraction of the total organic matter (National Academy of Sciences, 1977). Over 700 volatile organic compounds have been identified in drinking water (U.S. Studies beginning with those of Middleton and Rosen (1956) began to identify the specific organic compounds in drinking water and their removal by the carbon adsorption. However, it has long been recognized that these group parameters provide only estimates of performance for target compounds. The removal of organic compounds from drinking water has been based primarily on the measurement of organic matter as measured by carbon chloroform extract (CCE), total organic carbon (TOC), or other group parameters. During the past 20 yr, research on the use of adsorbents to treat drinking water has emphasized the removal of specific organics. 19:9 Maimonides, 1185) and there have been marked changes in the nature of the adsorbent since that time (Kunin, 1974a,b).ĭuring the twentieth century, GAC and powdered activated carbon (PAC) have been used in the United States to control taste and odors in drinking water (U.S. There has been an uninterrupted use of carbonaceous adsorbents since biblical times (Old Testament, Num. To ensure a thorough review of each topic, the data for each type of adsorbent were considered and reported separately.Ĭarbon and other adsorbents in various forms have been used for the treatment of water and as detoxifying pharmaceutical agents in medicine for many centuries. The subcommittee was confronted by a continual flow of new data and the need for postulation and interpretation. Where possible, stress was placed on studies of chemicals at nanogram to microgram per liter concentrations, which are typically found in drinking water. Studies that met established criteria for quality assurance and completeness of data were used as primary sources by the subcommittee. A large and diverse segment of the scientific literature, particularly that concerning recent European experience, was scrutinized. The subcommittee considered the ability of adsorbents to remove organic compounds of concern to health and the possible products of the adsorption process. Its scope of work included a review of work on:Īnalytical methods to monitor adsorption processes The subcommittee reviewed the pertinent literature and rigorously assessed the scientific data base. ![]() During the subcommittee's study, the EPA held hearings and received written comments regarding this treatment. Environmental Protection Agency (EPA) as the option of choice for the control of "synthetic organic chemicals" in drinking water. The use of GAC under specified conditions was proposed by the U.S. Different raw materials and manufacturing processes produce final products with different adsorption characteristics. The subcommittee defined ''activated carbon" as a family of carbonaceous substances that are characterized primarily by their surface area, pore size distribution, and sorptive and catalytic properties. The development of standards for GAC and the economic aspects of its use was not a part of this study. Some attention is given to an examination of the potential health effects related to the use of these adsorbents, but detailed toxicological and epidemiological implications resulting from the presence of organic compounds in drinking water are considered in separate chapters of Drinking Water and Health, Volume 3. This chapter contains the findings of the Subcommittee on Adsorption of the National Research Council's Safe Drinking Water Committee, which studied the efficacy of granular activated carbon (GAC) and related adsorbents in the treatment of drinking water.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |