Chlorine, surface water

Water in Industry. Freshwater for industry can often be replaced by saline or brackish water, usually after sedimentation, filtration, and chlorination (electrical or chemical), or other treatments (22). Such treatment is not necessary for the largest user of water, the electric power industry, which in the United States passed through its heat exchangers in 1990 about 40% of the total supply of surface water, a quantity similar to that used for agriculture, and it was 48% of the combined fresh and saline water withdrawals (10). Single stations of 1000 MW may heat as much as 12 Mm /d by as much as 10—15°C. 

Pretreatment For most membrane applications, particularly for RO and NF, pretreatment of the feed is essential. If pretreatment is inadequate, success will be transient. For most applications, pretreatment is location specific. Well water is easier to treat than surface water and that is particularly true for sea wells. A reducing (anaerobic) environment is preferred. If heavy metals are present in the feed even in small amounts, they may catalyze membrane degradation. If surface sources are treated, chlorination followed by thorough dechlorination is required for high-performance membranes [Riley in Baker et al., op. cit., p. 5-29]. It is normal to adjust pH and add antisealants to prevent deposition of carbonates and siillates on the membrane. Iron can be a major problem, and equipment selection to avoid iron contamination is required. Freshly precipitated iron oxide fouls membranes and reqiiires an expensive cleaning procedure to remove. Humic acid is another foulant, and if it is present, conventional flocculation and filtration are normally used to remove it. The same treatment is appropriate for other colloidal materials. Ultrafiltration or microfiltration are excellent pretreatments, but in general they are... 

The minimum residuals required for cyst destruction and inactivation of viruses are much greater. Although chlorine residuals in Table 4 are generally adequate, surface waters from polluted waterways are usually treated with much heavier chlorine dosages. Ordinary chlorination will destroy all strains of coli, aerogenes, pyocyaneae, typhsa, and dysenteria. 

The toxicity of chlorine residuals to aquatic life has been well documented. Studies indicate that at chlorine concentrations in excess of 0.01 mg/1, serious hazard to marine and estuarine life exists. This has led to the dechlorination of wastewaters before they are discharged into surface water bodies. In addition to being toxic to aquatic life, residuals of chlorine can produce halogenated organic compounds that are potentially toxic to man. Trihalomelhanes (chloroform and bromoform), which are carcinogens, are produced by chlorination. 

Note the table gives the quantity of oxygen dissolved in sea-water at dirferent temperatures and chlorinities when in equilibrium with a normal atmosphere saturated with water vapour, li thus represents the condition approached by the surface water when biological activity is not excessive. 

The elements Na, K, Cl, SO, Br, B, and F are the most conservative major elements. No significant variations in the ratios of these elements to chlorine have been demonstrated. Strontium has a small (< 0.5%) depletion in the euphotic zone (Brass and Turekian, 1974) possibly due to the plankton Acantharia, which makes its shell from SrS04 (celestite). Calcium has been known since the 19th century to be about 0.5% enriched in the deep sea relative to surface waters. Alkalinity (HCOf") also shows a deep enrichment. These elements are controlled by the formation... 

Very little recent information on concentrations of endrin in water could be found in the available literature. Unlike DDT, chlordane, aldrin/dieldrin, and a variety of other chlorinated pesticides, endrin was never used extensively in urban areas. This is reflected in the results from EPA s Nationwide Urban Runoff Program, which showed no detections in 86 high-flow water samples from 51 urbanized watersheds from 19 cities (Cole et al. 1984). Analysis of EPA STORET monitoring information from ambient surface water showed a significant percentage of detections for endrin (32% of 8,789 samples), but most were near the detection limits, with a national median concentration of 0.001 ppb (Staples et al. 1985). A similar analysis of STORET data for endrin aldehyde showed that this compound was not found in 770 samples of ambient surface water. More recently, endrin was not detected (detection limit 49 ng/L [0.045 ppb]) in surface water from the Yakima River Basin, Washington (Foster et al. 1993). However, in... 

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). 

Concentrate can be harmful to the environment due to either its higher than normal salinity, or due to pollutants that otherwise would not be present in the receiving body of water. These include chlorine and other biocides, heavy metals, antisealants, coagulants and cleaning chemicals. Of particular concern is the effect of pollutants on delicate ecosystems and endangered or threatened species. However, with appropriate measures in place, the discharge of concentrate to surface water can remain a viable method for seawater desalination plants. 

The rate of volatilization will also increase with an increase in temperature, ten Hulscher et al. (1992) studied the temperature dependence of Henry s law constants for three chlorobenzenes, three chlorinated biphenyls, and six polynuclear aromatic hydrocarbons. They observed that within the temperature range of 10 to 55 °C, Henry s law corrstant doubled for every 10 °C increase in temperature. This temperature relationship should be corrsidered when assessing the role of chemical volatilization from large surface water bodies whose temperatines are generally higher than those typically observed in groimdwater. 

Surface Water. Under oceanic conditions, aldrin may undergo dihydroxylation at the chlorine free double bond to produce aldrin diol (quoted, Verschueren, 1983). In a river die-away test using raw water from the Little Miami River in Ohio, 26, 60, and 80% of aldrin present degraded after 2, 4, and 6 wk, respectively (Eichelberger and Lichtenberg, 1971). 

Surface Water. In an estuary, the half-life of fenvalerate was 27-42 d (Schimmel et al., 1983). ChemicaPPhysical Undergoes hydrolysis at the ester bond (Hartley and Kidd, 1987). Decomposes gradually at 150-300 °C (Windholz et al., 1983) probably releasing toxic fumes of nitrogen and chlorine. 

But, given that not all bladder cancer victims smoke, work with dyes, or operate drill presses, where could the carcinogens be coming from Chlorine-treated drinking water is a possibility. Epidemiological surveys have revealed that people who drink surface water treated with chlorine are more likely to develop bladder cancer. How much more likely Estimates are that in North America we can link roughly 4,500 cases of bladder cancer annually to chlorinated water. To put this into more understandable terms, about ten out of every thousand men who do not drink chlorinated water will develop bladder cancer if they live to be seventy, while thirteen will do so if they drink chlorinated water for thirty-five years. This, of course, assumes that those who don t drink chlorinated water are consuming water that has been purified by some other technique, an option not available to most people. 

---