Chapter 14 Water Chemistry for Changing Times, Thirteenth Edition Lecture Outlines John Singer, Jackson Community College © 2013 Pearson Education, Inc.

2 Chapter 14 © 2013 Pearson Education, Inc. Water: Some Unique Properties Expands when it freezes

3 Chapter 14 © 2013 Pearson Education, Inc. High Heat of Vaporization Water has a very high heat of vaporization for a liquid. Therefore, a large amount of heat is required to vaporize a small amount of water. Water: Some Unique Properties

4 Chapter 14 © 2013 Pearson Education, Inc. Specific Heat Specific heat is the amount of energy necessary to raise the temperature of 1 gram of water 1 o C. Water: Some Unique Properties

5 Chapter 14 © 2013 Pearson Education, Inc. Specific Heat Water has a very high specific heat. Water: Some Unique Properties

6 Chapter 14 © 2013 Pearson Education, Inc. Water in Nature 75% of Earth’s surface is covered with water. Nearly 98% of that is seawater. About 2% of Earth’s water is frozen in the polar ice caps.

7 Chapter 14 © 2013 Pearson Education, Inc. The Water Cycle and Natural Contaminants

8 Chapter 14 © 2013 Pearson Education, Inc. Natural contaminants in water include Gases including radon, nonmetal oxides, and others. Dissolved minerals including cations and anions. Calcium, magnesium, and iron salts cause hard water. Organic Matter: Bacteria, microorganisms, and animal wastes are all potential contaminants of natural waters. The Water Cycle and Natural Contaminants

9 Chapter 14 © 2013 Pearson Education, Inc. The Water Cycle and Natural Contaminants

10 Chapter 14 © 2013 Pearson Education, Inc. Chemical and Biological Contamination Waterborne Disease Contamination of water by pathogenic organisms is a serious problem. The EPA estimates that 30 million people in the U.S. are threatened by bacterial contamination of water supplies. It is estimated that 80% of all illness in the world is caused by water contamination.

11 Chapter 14 © 2013 Pearson Education, Inc. Acid Rain Sulfur and nitrogen oxides (SO x and NO x ) are deposited as acid rain. Acidic precipitation damages the environment by lowering the pH of soil, lakes, and streams. Acid rain also can corrode metals and dissolve limestone and marble Chemical and Biological Contamination

12 Chapter 14 © 2013 Pearson Education, Inc. Sewage and Dying Lakes The release of sewage into waterways increases the biochemical oxygen demand (BOD) and leads to eutrophication (aging) of a lake. Organic matter can undergo either aerobic or anaerobic decay. Chemical and Biological Contamination

13 Chapter 14 © 2013 Pearson Education, Inc. Chemical and Biological Contamination

14 Chapter 14 © 2013 Pearson Education, Inc. The Water Cycle and Natural Contaminants Sewage and Dying Lakes Eutrophication is a natural process that is accelerated by the presence of human waste and runoff from farms, lawns, and other human activity.

15 Chapter 14 © 2013 Pearson Education, Inc. Industrial Water Use Manufacturing processes produce waste products and use water resources.

16 Chapter 14 © 2013 Pearson Education, Inc. Groundwater Contamination Approximately one-half of the U.S. population gets its drinking water from groundwater sources. Groundwater sources in many parts of the country are contaminated. Groundwater is easy to contaminate and difficult, as well as expensive, to clean up.

17 Chapter 14 © 2013 Pearson Education, Inc. Nitrates Nitrate contamination of groundwater is a problem particularly in rural areas. Agricultural activity contributes fertilizers and animal wastes to water sources. Nitrates are very soluble. They are therefore difficult to remove from water supplies. Infants around one year old and younger can metabolize nitrate to nitrite. Nitrite ions then form complexes with heme and the baby can turn blue and die. This condition is known as methemoglobinemia (blue baby syndrome). Groundwater Contamination

18 Chapter 14 © 2013 Pearson Education, Inc. Nitrates Groundwater Contamination

19 Chapter 14 © 2013 Pearson Education, Inc. Volatile Organic Chemicals (VOCs) VOCs can contaminate groundwater and add undesirable odor to drinking water. Also, many are carcinogenic. Sources include industrial activity, oil and brine wells, landfills, leaking underground storage tanks, and illegally dumped of organic wastes. Groundwater Contamination

20 Chapter 14 © 2013 Pearson Education, Inc. Making Water Fit to Drink More than 170,000 public water systems exist in the United States. The per capita use of water in the U.S. is almost 2 million liters per year. This includes water used for industrial, agricultural, and personal purposes. This use exceeds the per capital use of other nations.

21 Chapter 14 © 2013 Pearson Education, Inc. Making Water Fit to Drink The United States Safe Drinking Water Act was first passed in It was amended in 1986 and The act authorizes the EPA to set, monitor, and enforce national health-based standards for contaminants in municipal water supplies.

22 Chapter 14 © 2013 Pearson Education, Inc. The United States Safe Drinking Water Act Making Water Fit to Drink

23 Chapter 14 © 2013 Pearson Education, Inc. Parts per Million (ppm) 1 ppm = 1 g solute 10 6 g solution 1 ppb = 1 g solute g solution Parts per Billion (ppb) Making Water Fit to Drink

24 Chapter 14 © 2013 Pearson Education, Inc. Water Treatment Plants In most urban areas, water is treated at a water treatment plant before it is distributed to homes for consumption.

25 Chapter 14 © 2013 Pearson Education, Inc. The first step in water treatment is to add slaked lime and alum to the water: The slaked lime and alum form gelatinous aluminum hydroxide, which coagulates colloidal particles along with bacteria. These are then removed by filtering through sand and gravel filters. Charcoal is often present in the filtering process to remove odors and the water is aerated to improve taste. Water Treatment Plants

26 Chapter 14 © 2013 Pearson Education, Inc. Chemical Disinfection Chlorine is added to kill any remaining bacteria. Municipal drinking water often contains residual chlorine so that the water can be free from bacteria at any point in the distribution system. Ozone can also be used for bacterial disinfection and has the added advantage of killing many viruses. Water Treatment Plants

27 Chapter 14 © 2013 Pearson Education, Inc. Water Treatment Plants

28 Chapter 14 © 2013 Pearson Education, Inc. Other Technologies Ultraviolet light (UV) can also be used to disinfect water. It is most effective in small-scale applications. One disadvantage is that it does not offer the residual protection that chlorine or ozone does. Water Treatment Plants

29 Chapter 14 © 2013 Pearson Education, Inc. Fluorides Many municipal water supplies have fluoride added to help prevent tooth decay. Water Treatment Plants

30 Chapter 14 © 2013 Pearson Education, Inc. Fluorides Tooth enamel is composed of a calcium phosphate complex called hydroxyapatite. Fluoride ions replace some of the hydroxide ions, making the enamel harder and less affected by acids. Water Treatment Plants

31 Chapter 14 © 2013 Pearson Education, Inc. Fluorides Water is fluoridated by adding H 2 SiF 6 or Na 2 SiF 6 to a concentration ppm. Early studies showed a 50% to 70% reduction in dental caries (cavities) in populations using fluoridated drinking water. Fluoridation of drinking water is not without controversy. Some people object to the fluoridation of drinking water. Water Treatment Plants

32 Chapter 14 © 2013 Pearson Education, Inc. Before wastewater can be returned to the environment, it should be treated to remove harmful contaminants. Municipal wastewater treatment can involve up to three levels of processing. Wastewater Treatment

33 Chapter 14 © 2013 Pearson Education, Inc. Primary sewage treatment involves holding the sewage in settling ponds to allow heavier solids to precipitate out as sludge. Wastewater Treatment

34 Chapter 14 © 2013 Pearson Education, Inc. Secondary sewage treatment involves passing the effluent from the primary treatment through sand and gravel filters. During this process, aerobic bacteria can break down much of the organic matter. Wastewater Treatment

35 Chapter 14 © 2013 Pearson Education, Inc. Another form of secondary treatment is called the activated sludge method. The sewage is placed into tanks and aerated with large blowers. Wastewater Treatment

36 Chapter 14 © 2013 Pearson Education, Inc. Tertiary treatment involves further treatment for the sewage, such as charcoal filtration to absorb organic molecules, reverse osmosis, further filtration, distillation, etc. Wastewater Treatment

37 Chapter 14 © 2013 Pearson Education, Inc. Wastewater Treatment

38 Chapter 14 © 2013 Pearson Education, Inc. The Newest Soft Drink: Bottled Water Bottled water is the fastest growing and most profitable segment of the beverage industry. Per capita consumption is 90 liters per year and growing. Many people think that drinking bottled water is better for one’s health than drinking tap water. In many cases, bottled water is someone else's tap water.

39 Chapter 14 © 2013 Pearson Education, Inc. Alternative Sewage Treatment Systems Sludge from municipal sewage treatment systems can be used as fertilizer. A number of communities allow primary treatment in settling ponds. The effluent is then allowed to flow into marshes that filter the sewage and use the nutrients. Toilets have been developed that compost wastes. Composting toilets use no energy or water.

40 Chapter 14 © 2013 Pearson Education, Inc. We Are the Solution to Water Pollution Water is essential to our quality of life. We must do what we can to maintain the quality of our water sources.