Drinking water, Chapter

Chlorine is used to make PVC plastic as well as household bleaches. It is also used to kill bacteria and viruses in drinking water (Chapter 11, p. 191). 

The most significant application of reverse osmosis has been in the field of desalination to produce drinking water. Other important apphcations include the treatment of industrial waste water, concentration of fruit juices, and concentration of weak solutions such as aqueous ethanol [3-6]. The rest of the chapter will focus almost entirely on semi-permeable membranes used for reverse osmosis based applications. We chose this focus in view of the importance of reverse osmosis as a rather efficient separation technique for separating a wide range of solutions, especially very dilute solutions—which are usually notoriously difficult to handle using conventional techniques such as distillation. 

The products of this electrolysis have a variety of uses. Chlorine is used to purify drinking water large quantities of it are consumed in making plastics such as polyvinyl chloride (PVC). Hydrogen, prepared in this and many other industrial processes, is used chiefly in the synthesis of ammonia (Chapter 12). Sodium hydroxide (lye), obtained on evaporation of the electrolyte, is used in processing pulp and paper, in the purification of aluminum ore, in the manufacture of glass and textiles, and for many other purposes. 

Methyl parathion can enter your body if you eat food or drink water containing it if you swim, bathe, or shower in contaminated water if you touch recently sprayed plants or soil if you touch contaminated soil near hazardous waste sites or if you breathe air that contains methyl parathion, such as near factories or recently sprayed farm fields (or in recent accounts of the illegal use of methyl parathion, if you breathe air or touch contaminated surfaces inside homes where methyl parathion has been used to kill insects). By any means of exposure, methyl parathion goes into your body quickly and gets into your blood. From your bloodstream, methyl parathion goes to your liver, brain, and other organs. Your liver changes some of methyl parathion to a more harmful chemical called methyl paraoxon. Both methyl parathion and methyl paraoxon can bind to enzymes of your nerves within minutes or hours. Your liver breaks down methyl parathion and methyl paraoxon into less harmful substances. These less harmful substances leave your body in urine within hours or days. For more information, see Chapter 3. 

Propagated outbreaks of infection relate to the direct transmission of an infective agent from a diseased individual to a healthy, susceptible one. Mechanisms of such transmission were described in Chapter 4 and include inhalation of infective aerosols (measles, mumps, diphtheria), direct physical contact (syphilis, herpes virus) and, where sanitation standards are poor, through the introduction of infected faecal material into drinking water (cholera, typhoid). The ease oftransmission, and hence the rate of onset of an epidemic (Fig. 16.3) relates not only to the susceptibility status, and general state of health of the individuals but also to the virulence properties of the organism, the route oftransmission, the duration of the infective period associated with the disease. 

U.S. EPA s MTBE Treatment Profiles Website3 provides site-specific data about the use of in situ and ex situ technologies that have been used to treat MTBE in groundwater, soil, and drinking water. The website contains information about more than 400 projects, including information about the technology used, project scale, performance, and cost. The treatment performance and cost data presented in this chapter provide readers with... 

Most lead used by industry comes from mined ores ("primary") or from recycled scrap metal or batteries ("secondary"). Human activities (such as the former use of "leaded" gasoline) have spread lead and substances that contain lead to all parts of the environment. For example, lead is in air, drinking water, rivers, lakes, oceans, dust, and soil. Lead is also in plants and animals that people may eat. See Chapter 3 for more information on the physical and chemical properties of lead. Chapter 4 contains more information on the production and use of lead. 

Birth defects have been seen in animals exposed to high concentrations of acrylonitrile in the air or drinking water. Reproductive effects have been seen in animals given acrylonitrile in drinking water for three generations. However, no birth defects or effects on reproduction have been reported in humans. Further information on the health effects of acrylonitrile in humans and animals can be found Chapter 2. 

Tables 1-1 through 1-4 show the relationship between exposure to acrylonitrile and known health effects. Short-term and longer-term Minimal Risk Levels (MRLs) are also included in Tables 1-1 and 1- 3. These MRLs were derived from animal and human data for both short-term and long-term exposure, as described in Chapter 2 and in Tables 2-1 and 2-2. The MRLs provide a basis for comparison with levels that people might encounter either in the air or in food or drinking water. If a person is exposed to acrylonitrile at an amount below the MRL, it is not expected that harmful (noncancer) health effects will occur. Because these levels are based only on information currently available, some uncertainty is always associated with them. Also, because the method for deriving MRLs does not use any information about cancer, an MRL does not imply anything about the presence, absence, or level of risk for cancer.

In recognition of the increased vulnerability of the developing organism, both the U.S. EPA Food Quality Protection Act [77] and the U.S. EPA Safe Drinking Water Act [78] mandate that infants and children warrant special consideration in the risk assessment process. Immune system ontogeny and the sensitivity of the developing immune system to xenobiotics are discussed in detail in chapter 20 of this volume. 

We mentioned in Chapter 2 (Section 2.6.1) that a purge-and-trap procedure sometimes precedes an analysis by gas chromatography. An example of this procedure is found in the City of Lincoln, Nebraska, Water Treatment Plant Laboratory. Water treatment includes chlorination. When water is chlorinated, chlorine reacts with organic matter to form trihalomethanes (THMs), such as chloroform, bromoform, bromodichloromethane, and chlorod-ibromomethane. THMs in water are regulated by the Safe Drinking Water Act, and so the laboratory must analyze the treated water to determine their concentration. 

The mobility of very slowly degradable compounds or persistent metabolites present in surface water or bank filtration-enriched ground water is of particular interest for the production of potable water. In common with many other compounds, certain surfactants, and especially their polar metabolites, have the potential to bypass the technical purification units used, which may include flocculation (active charcoal) filtration, ozonation or chlorination, and thus can be found ultimately in drinking water destined for human consumption (see Chapter 6.4). 

Investigation of NPEC in European rivers used as raw waters in drinking water production revealed values in the lower pgL-1 range (see Chapter 6.3). 

Studies in humans and animals indicate that most of the phenol that enters the body through skin contact, breathing contaminated air, eating food or drinking water, or using products containing phenol, leaves the body in the urine within 24 hours. Chapter 2 contains additional information about how phenol enters and leaves the body. 

ADP ribosylation results in inhibition of GTPase activity and hence maintains the a-subunit in the active form. The constant activity of the G-protein results in an increase in adenyl cyclase activity and therefore a chronic increase in the cychc AMP level. This stimulates an ion channel in the enterocyte which results in a loss of Na ions and hence water from the cells into the intestine. This leads to diarrhoea and a massive loss of fluid from the body which can be sufficiently severe to result in death. Since 2000 there have been epidemics in South America and parts of central Africa. Infection is usually caused by drinking water contaminated with faecal matter. Treatment consists of hydration with rehydration fluids (Chapter 5). 

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