environmental engineering past paper 2005-12

environmental engineering past paper 2005-12 - THE...

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Unformatted text preview: THE UNIVERSITY OF HONG KONG BACHELOR OF ENGINEERING: LEVEL I EXAMINATION DEPARTMENT OF CIVIL ENGINEERING ENVIRONMENTAL ENGINEERING (CIVL 1005) DECEMBER 15, 2005 TIME: 10:00 AM — 12:00 PM (2 hours) Answer ALL questions Only one correct answer for each question. Giving more than one answer to a question is considered a wrong answer. Each question carries 4 marks. One mark will be deducted for each wrong answer. Use of Electronic Calculators: Candidates may use any calculator, which fulfils the following criteria: (a) it should be self-contained, silent, battery—operated and pocket-sized; (b) it should have numeral-display facilities only and should be used only for the purpose of calculation; (0) it should not have any printing device, alphanumeric keyboard, or graphic display; and (d) it should not contain any recorded data or program. It is the candidate's responsibility to ensure that the calculator operates satisfactorily and the candidate must record the name and type of the calculator on the front page of the examination scripts. Lists of permitted/prohibited calculators will not be made available to candidates for reference, and the onus will be on the candidate to ensure that the calculator used will not be in violation of the criteria listed above. 1. In fossil fuel power plants, chemical energy in fossil fuel is converted into electricity. What is the maximum energy conversion efficiency in a typical fossil fuel power plant of modern design: (a) 25%, (b) 35%, (c) 45%, or (d) 55%. 2. What is the closest value of ultimate BOD for a wastewater sample which has a BODZ of 100 mg/l and a BOD5 of 200 mg/l: (a) 400 mg/l, (b) 360 mg/l, (c) 320 mg/l, or (d) 280 mg/l. 3. Which of the following statements is false? Fossil fuel power plants in China are the common source of (a) thermal pollution, (b) PM10, (c) BTX., or ((1) acid rain, 4. Most people rely on surface water (i.e. water in rivers and lakes) for their fresh water supply. It has been estimated that the Planet Earth has a total of 1.384x109 km3 water. Of which, how many percent is the fresh surface water: (a) less than 0.01%, (b) 0.01—0.05%, (c) 0.05-0.10%, and (d) over 0.10%. ' 5. Solubility of oxygen in water depends on a number of environmental parameters, including altitude, salinity and temperature. To you best estimate, what is the saturated dissolved oxygen level in seawater at 5°C: (a) 5 mg/L, (b) 10 mg/L, (0) 15 mg/L, or (d) 20 mg/L. Page 1 of 3 10. ll. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. Which of the following pollutants is strictly anthropogenic: (a) methane, (b) ozone, (c) DDT, or (d) nitrous oxide. E. coli is the key indicator for bacterial pollution. Which one of the following descriptions E. coli is false: (a) it is a good indicator of sewage pollution, (b) it is a serious pathogen, (c) it has a relatively high survival rate in natural environment, or ((1) its analytical method has well been established. Which of the following statement is false for a typical raw sewage: (a) COD > BOD5, (b) N > P, (c) oxidized N > reduced N, and (d) BOD5 > (N + P). (N and P represent the nitrogen and phosphorus contents, respectively.) In most marine waters, nitrogen is the limiting nutrient for the growth of algae, with 0.3 mg/L considered as the critical concentration. At what concentration would phosphorus become the limiting nutrient: (a) 10 mg/L, (b) 1 mg/L, (0) 0.1 mg/L, or (d) 0.01 mg/L. Which of the following statement is false? Disinfection by—products are (a) resulting from chlorination, (b) carcinogenic, (c) due to the presence of residual organic matter in water, or (d) not removable by reverse osmosis. The presence of multivalent cations, most notably calcium and magnesium ions, is referred to as water hardness. Chemicals are used to precipitate these two cations in the forms of: (a) CaC03 and MgCO3, (b) Ca(OH) 2 and Mg(OH)2, (c) CaCO3 and Mg(OH)2, or (d) Ca(OH) 2 and MgCO3. Which of the following statement is correct? Trickling filter is (a) merely a laboratory device which is impractical for field applications, (b) a design which removes pollutants according to their sizes, (0) a design which needs land, or (d) a device which removes bacteria from drinking water. Assuming an annual worldwide population growth rate of 3%, what is the most likely world population by 2024? (a) 10.5 billion, (b) 11.5 billion, (0) 12.5 billion, or (3) 13.5 billion. Activated carbon is an effective adsorbent due to its vast surface area. Each kilogram of activated carbon typically has a surface area of about: (a) 1x103 m2, (b) 1x104 m2, (c) 1x105 m2, or (d) 1x106 m2. Calcium and magnesium contribute to the water hardness. Water may be softened by the following processes except: (a) addition of lime, (b) ion exchange, (c) reverse osmosis, and (d) activated carbon adsorption. Which one of the following is a correct description of BTX: (a) pesticide, (b) industrial surfactant, (0) chelating agent, and (d) petroleum-based pollutants. Cigarette smoking does not emit (a) benzene, (b) PAHs, (0) formaldehyde, or (d) ozone. Radon is (a) pathogen, (b) water pollutant, (c) air pollutant, or (d) disease. Which of the following constituents in the atmosphere, in addition to carbon dioxide (C02), can cause greenhouse effect: (a) moisture, (b) PM 2.5, (c) sulfur dioxide ($02), or (d) carbon monoxide. Adiabatic lapse rate is a measurement of the atmospheric temperature drop for the increase of altitude. Which of the following statement is false? According to thermodynamics, adiabatic lapse rate is dependent on (a) humidity, (b) specific heat of air, (0) latitude, or ((1) carbon dioxide content. Which one of the following is a false description of ozone: (a) it is a pollutant emitted from landfills, (b) it absorbs UV energy of solar radiation in stratosphere, (c) it is a disinfectant, and (d) its concentration in atmosphere is less than 0.1 part per million (by volume). Page 2 of 3 22. 23. 24. 25. Electrostatic precipitators use very high negative voltage normally in the range of (a) 1000-10,000 V, (b) 10,000—100,000 V, (c) 100,000-1,000,000 V or (d) higher than 1,000,000 V. Solid and hazardous wastes may be disposed of by incineration. However, incineration may lead to a number of environmental concerns. Which one of the following concerns is in general unrelated to incineration of these wastes: (a) particulates, (b) dioxins, (c) heavy metals in ashes, or (d) contamination of groundwater. Which of the following statements are true?: (a) A 2 dB drop in sound pressure level will be experienced for a doubling of the distance from the sound source, (b) A 3 dB drop in sound pressure level will be experienced for a doubling of the distance from the sound source, (c) A 2 dB increase in sound pressure level is caused by a doubling of the sound power, or (d) A 3 dB increase in sound pressure level is caused by a doubling of the sound pressure. Which of the following statement is false: (a) Over 90% of fresh water in HK is from the East River in Guangdong Province, (b) A golf driving range in HK is built on top of restored landfill site, (0) Sludge from HK wastewater treatment plants has to be dewatered to a moisture content of below 70% before it can be disposed of by landfilling, or (d) HK has an annual rainfall of about 2300 mm. - END OF PAPER - Page 3 of 3 ...
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