Pollution, water

Water Source Water Volume (cubic miles) Mass (kg) Percent of Total Water 

SOURCE Adapted from the U.S. Geological Survey at http //ga.water.usgs.gov/edu/waterdistribution.html.  

But the dirt and grime from our clothes must end up somewhere, and that somewhere is in the water that we discharge from our homes. The Law of Conservation of Matter says that matter can be neither created nor destroyed. The atoms and molecules that we dissolve into the water in our washing machines are only being removed to another location. 

Atkins, Peter W. (1987). Molecules. New York Scientific American Library. 

Leopold, Luna B. Davis, Kenneth S. and the Editors of Life (1966). Water. New York Time Incorporated New York. 

Priority Water Pollutants 74 Chemical Reactions in Water 78 

There are virtually no sources of drinking water on earth that are not contaminated with xenobiotics. Rainwater cleanses the atmosphere as it forms and falls. As a result, it contains dissolved acids, organic compounds, and heavy metals such as mercury and selenium in many areas. Surface collection basins from which potable water is drawn—rivers, streams, and lakes—accumulate ground level pollutants in addition to those carried in rainwater. Underground water, which is somewhat filtered and generally contains lesser quantities of pollutants than surface water, may itself be contaminated by ground releases of toxicants and by contaminants produced by chemical reactions in the soil and water. 

Water intended for human consumption that is biologically contaminated is treated to remove bacteria, viruses, fungi, and parasites, by aeration, chlorination, ozone, ultraviolet radiation, or a combination of these methods. In the process of purification, decontamination by-products (DBPs) are produced. These are chemicals that are themselves toxic. DBPs will be discussed in Section 8.9. 

Major sources of water pollutants include mining, manufacturing, farming, power production, and runoff from urban and suburban sprawl. Water pollution from each of these sources is discussed in the following sections. 

Mining activities frequently impact water resources and contaminate surface water and groundwater systems. This is illustrated by the following examples. 

The pH of rainwater is normally about 6 but can be reduced significantly by absorption of acidic exhaust gases from power stations, industrial combustion or other processes, and vehicles. Acids may also enter the waterways as a component of industrial effluent. In addition to the direct adverse effects on aquatic systems (Table 13.9), low pH can result in the leaching of toxic metals from land etc. 

Cyanides can be fatal to fish at clppm. Because of concern over the possible in vivo conversion of nitrate into carcinogenic nitrosamines, the nitrate content of drinking water must be strictly controlled. Nitrate and phosphate pollution can also cause eutrophication in still or slow-moving warm waters by stimulation of algae growth in the presence of 

Period Basic working week, e.g. 40hr/wk, Continual unless area vacated  

Levels Possibly measurable fractions of Normally very low at limits of 

Generally single pollutants Mixture of primary pollutants, from 

Population Adults (16-65) Fit for work (Health possibly monitored) All population including infants, aged and infirm 

Period Basic working week, e.g. 40 hr/wk, 48wk/yr plus overtime therefore intermittent elimination and recovery times Continual unless area vacated therefore elimination and recovery depend on irregular periods of low/ zero concentrations 

Levels Possibly measurable fractions of OESs (mg/m ) Normally very low at limits of analytical/instrumental sensitivity (gg/m ) 

The largest natural water body is oceans. The total mass of the Earth s oceans has been estimated to be about 1.4 x 10 kg (or 1.4x 10 t). The sea water is salty it contains a lot of ionic compounds, the highest among which are sodium (Na ), potassium (K+), magnesium (Mg +), and calcium (Ca ) cations, and chloride (C1 ) and sulfate (SO ) anions. Their concentrations are in the order of Na (10 g (=0.4 3 mol)/L) Mg + Ca + K+, and Cl (19 g (=0.54 mol)/L) SO. In addition, seawater contains a large variety of elanents (their cations and anions). About 70 elements have been identified in seawater, and certainly others are also present but may not be detected by currently available techniques. 

Water pollution is multifaceted. As there is no (chemically) pure water in nature, what constitutes pollution is a difficult issue. Shall we define nonpolluted water to be that fit for human consumption, i.e., potable or drinkable Well, this is too narrow a definition. Seawater, polluted or not, is undrinkable. How about nonpris-tine But can we really define fhe pristine condition No, we cannot. 

Pollntion occnrs most often in the wastewater released from domestic and industrial sources. Treatment of snch a wastewater or how polluting substances may be prevented from escaping into the wastewater is an important critical issue. Chemistry and microbiology play important roles in these treatments for reducing water pollution. Analytical chemistry identifies and quantifies the polluting chemicals. Some chemical pollntants are talked abont later in the book (Part V). 

The measure of water pollution is the volume of pure water (dm ) that should be used to dilute liquid emissions produced over the whole life-cycle of the product (extraction, production of electricity, etc. and in transportation). 

A second area of the applicahon of cements for environmental purposes is that of the stabilization/immobilization of Hquid toxic industrial waste, and in parhcu-lar that of hazardous heavy-metal waste streams containing chromium, vanadium, cadmium, and other metals. As noted in Sechon 5.2.4.2, both Cr and V can enter the inter-chain spaces of ettringite to replace groups (Buhlert and Kuzel, 

Studies of the immobilization behavior of Cd, Cr, and V in the cement matrices shown above revealed that (i) Cd is effectively retained in all cements and shows no sensitivity to the leachate pH and (ii) both NMLs of Cr and V are maximized at intermediate levels of alumina in the cement matrix and minimized at high and low alumina contents, presumably related to the amphoteric nature of Al (Heimann et al, 1992 Ivey et al, 1990). Multicomponent systems tests of the interaction of cement and radioactive waste forms (used UO2 fuel, fuel recycle waste glass) have provided evidence that actinides (plutonium 239 -1- 240, americium 241, curium 244) would be efficiently adsorbed onto cement (Heimann, 1988a), presumably related to the presence of apatite structures (Beall and Allard, 1982). 

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In water pollution studies, the oxygen content can be measured by making the water alkaline and shaking a measured volume with an oxygen-free solution containing Mn- (aq). The solution is acidified with sulphuric acid, potassium iodide added and the liberated iodine titrated with sodium thiosulphate. 

The trend in the use of deep bed filters in water treatment is to eliminate conventional flocculators and sedimentation tanks, and to employ the filter as a flocculation reactor for direct filtration of low turbidity waters. The constraints of batch operation can be removed by using one of the available continuous filters which provide continuous backwashing of a portion of the medium. Such systems include moving bed filters, radial flow filters, or traveling backwash filters. Further development of continuous deep bed filters is likely. Besides clarification of Hquids, which is the most frequent use, deep bed filters can also be used to concentrate soflds into a much smaller volume of backwash, or even to wash the soflds by using a different Hquid for the backwash. Deep bed filtration has a much more limited use in the chemical industry than cake filtration (see Water, Industrial water treatment Water, Municipal WATERTREATiffiNT Water Water, pollution and Water, reuse). 

Beneficiation faciUties require air and water pollution control systems, including efficient control of dust emissions, treatment of process water, and proper disposal of tailings (see AiRPOLLUTlON CONTROLMETHODS). In handling finished fluorspar, operators must avoid breathing fluorspar dust and contacting fluorspar with acids. Proper disposal of spills and the use of respirators and other personnel protective equipment must be observed. Contact with fluorspar may irritate the skin and eyes. 

Glean Water Act. The Water QuaUty Act of 1987 and Clean Water Act of 1977 amended the Water Pollution Control Act of 1972, and are known collectively as the Clean Water Act (CWA). Their objective is to restore and maintain the integrity of U.S. waters. There are spill prevention, control, and containment requirements with which to comply. It requires replacement of older storage tanks or installation of double bottoms or seals. 

Zinc. The electrowinning of zinc on a commercial scale started in 1915. Most newer faciUties are electrolytic plants. The success of the process results from the abiUty to handle complex ores and to produce, after purification of the electrolyte, high purity zinc cathodes at an acceptable cost. Over the years, there have been only minor changes in the chemistry of the process to improve zinc recovery and solution purification. Improvements have been made in the areas of process instmmentation and control, automation, and prevention of water pollution. 

K. Rakness and co-workers, paper presented at Water Pollution Control Eederation Conference Workshop, Oct. 1979. 

Solid and Hazardous Waste. Regulation of pollution resulting from soHd waste disposal was formulated at a much slower pace than regulation of air or water pollution. It was not until the Resource Conservation and Recovery Act (RCRA) of 1976 (6) was passed that substantial controls were authorized. 

Overland water flow appHes shear forces to sod surfaces. When shear forces exceed the stress required to overcome cohesive forces between sod particles, the particles are detached and suspended in the flow. Suspended particles are carried into surface sod with infiltrating water where they block pores and initiate seal formation (47). Thus, erosion results in reduced water infiltration as well as loss of sod from the field and consequent downstream water pollution. If erosion is controlled, good water infiltration is maintained. 

J. Water Pollut. Control Fed, annual review issues. 

Water Environment Eederation (formerly Water Pollution Control Eederation), Hazardous Waste Treatment Processes, Manual of Practice ED-18, prepared by Task Eorce on Hazardous Waste Treatment, Alexandria, Va., 1990. 

W. W. Eckenfelder, Jr., Industrial Water Pollution Control, McGtaw-HiU Book Company, New York, 1966. 

Ideally the historical record of stream water quaUty would extend back to a time when human activities in the drainage basin had no significant effects. This "pristine" condition had probably already passed in most U.S. rivers before any organized water quaUty studies were made, as concern about apparent stream pollution was commonly a motivating factor in starting such studies (see Water, pollution). 

The products of human activities find their way into the environment and disturb ecosystems. Pollution has altered the surroundings to the detriment of humanity. In the last several decades, the poUutional load has increased, and its character has changed (see Water—pollution). 

Over the past decade, water pollution control has progressed from an art to a science. Increased emphasis has been placed on the removal of secondary pollutants, such as nutrients and refractory organics, and on water reuse for industrial and agricultural purposes. This in turn has generated both fundamental and appHed research, which has improved both the design and operation of wastewater treatment faciUties. 

Solving water pollution problems today involves a multidisciplinary approach in which the required water quaUty is related to agricultural, municipal, recreational, and industrial requirements. In many cases, a cost—benefit ratio must be estabUshed between the benefit derived from a specified water quaUty and the cost of achieving that quaUty. 

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