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Unformatted text preview: THE UNIVERSITY OF HONG KONG BACHELOR OF ENGINEERING: LEVEL; I )EXAMINATION DEPARTMENT OF CIVIL ENGINEERING (Environmental Engineering) (May 31, 2004) (CIVL 1005) TIME: 2:30 pm - 4:30 pm (2 hours) Answer ALL questions 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)
(d) it should be self-contained, silent, battery-operated and pocket-sized; it should have numeral-display facilities only and should be used only for the purpose
of calculation; it should not have any printing device, alphanumeric keyboard, or graphic display; and
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. The air quality standard for carbon monoxide based on an 8-hour measurement is 9.0
ppm, which is corresponding to which of the following values: (a) 10 mg/m3, (b) 11
mg/m3, (c) 12 mg/m3 or (d) 13 mg/m3. (Atomic weight: C 12; O 16) A room with volume 500 m3 has 50 smokers in it, each smoking two cigarettes per hour.
An individual cigarette emits about 1.4 mg of formaldehyde (HCHO). Formaldehyde
converts to carbon dioxide with a reaction rate coefﬁcient of K = 0.40/hr. Fresh air enters
the room at the rate of 1000 m3/hr, and stale air leaves at the same rate. Assuming
complete mixing, what is the steady state concentration of formaldehyde in the air at
25°C: (a) 0.080 ppm, (b) 0.085 ppm, (c) 0.090 ppm, or (d) 0.095 ppm. (Atomic weight:
C 12; O 16; H 1) Chloroﬂuorocarbons (CFCs) are known to cause the depletion of stratospheric ozone.
They had been widely used in numerous industrial applications due to certain
physicochemical properties until the recent decade. Which of the following descriptions
of CFCs is false: (a) nontoxic, (b) water soluble, (c) nonﬂammable, or (d) nonreactive.
Living organisms in nature store food in cells in the form of polysaccharides, of which
starch is the most abundant in plants and glycogen in animals. Polysaccharides have the
chemical formula of (C6H1005)n, where n is the number of repeated units. Based on this
chemical formula, what is the closest estimate of theoretical oxygen demand for each gram of starch: (a) 100 g, (b) 150 g, (c) 200 g, or (d) 250 g.
l 10. ll. 12. 13. 14. 15. 16. 17. 18. 19. 20. Cryptosporidz'um was on the headline of newspapers all over the world in 2000. It was
found in Sydney’s drinking water supply a few months before the 2000 Olympics Games,
causing a serious concern worldwide. Cryptosporidium is a: (a) virus, (b) bacterium, (c)
protozoan, or (d) helminth. The BOD reaction rate constant, k (natural log basis), and BODs/COD ratio of a typical
municipal wastewater are approximately: (a) 0.5 day"1 and 0.5, (b) 0.5 day'1 and 0.2, (c)
0.2 day" and 0.5, or (d) 0.2 day'1 and 0.1. Ammonia (NH3) dissolves in water forming NH4Jr and OH'. The equilibrium constant for
this reaction is 1.82 x 105. In order to remove NH4+ from water by stripping, the pH of
the water has to be adjusted. At Which of the following pH levels that over 99.8% of
NH4Jr becomes NH3: (a) 10.5, (b) 11, (c) 11.5, or (d) 12. 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 (d)
its analytical method has well been established. Activated sludge is (a) physical wastewater treatment, (b) chemical wastewater treatment
process, (c) biological wastewater treatment process, or (d) wastewater treatment reagent.
Disinfection is the ﬁnal treatment process in many water treatment plants. Although
chlorination is the most commonly used, there are many other disinfection processes
being used. Identify the process in the following which is not a disinfection process: (a)
ozonation , (b) reverse osmosis, (c) activated carbon, or ((1) UV irradiation. A sample of groundwater has 100 mg/L of Ca2+ and 10 mg/L of Mg“. (Atomic weights:
Ca 40.1; Mg 24.3; C 12; O 16). What are the hardness expressed in meq/L and mg/L as
CaC03: (a) 5.8 meq/L and 291 mg/L; (b) 2.9 meq/L and 291 mg/L; (0) 5.8 meq/L and
146 mg/L; or (d) 2.9 meq/L and 146 mg/L. Which one of the following descriptions for a secondary sewage treatment plant is false:
(a) suspended solids in the sewage accounted for over 1/3 of total BOD, (b) solids
removed from the primary settling tank are mostly biomass, (c) sludge handling and
disposal are as expensive as BOD reduction, or (d) chlorination of treated efﬂuent is not
required in Hong Kong. Which one of the following descriptions of anaerobic sludge digestion is false: (a) it
produces only methane and no carbon dioxide, (b) the biogas produced may be used to
generate electricity, (0) the digestion process may take weeks to complete, or (d) the
digested sludge requires further treatment before incineration or landﬁlling. Activated carbon is an effective adsorbent due to its vast surface area. Each gram of
activated carbon typically has a surface area of about: (a) 10 m2, (b) 100 m2, (0) 1,000
m2, or (d) 10,000 m2. What is the major constituent in the acid rain: (a) carboxylic acid, (b) hydrochloric acid,
(0) nitric acid, or (d) sulfuric acid. Which one of the following descriptions on the effect of acid rain is false: (a) corrosion
of metals, (b) eutrophication of lakes, (0) damage of crop yield, or (d) leaching of toxic
metals from soil. Which of the following air pollutants is not involved in the photochemical reactions of
forming smog: (a) ozone, (b) nitrogen oxides, (c) volatile organic chemicals, or (d)
asbestos. Photocopying machines may produce which of the following air pollutants: (a) carbon
monoxide, (b) carbon dioxide, (0) nitrogen oxides, or (d) ozone. The overall air quality may be represented by the Air Pollution Index (API), which is
announced daily by the Environmental Protection Department through news media. An
API of 95 means the air quality is (a) moderate, (b) unhealthy, (c) very unhealthy, or (d)
hazardous. Which of the following statements is most likely to be false: (a) building ventilation and
air conditioning are two different indoor environment engineering systems, (b) indoor air
quality can be more signiﬁcant than outdoor air quality in terms of impact on our health, 2 21. 22. 23. 24. 25. (c) ventilation is just about supplying fresh outdoor air into a building, or (d) indoor air
quality in ofﬁces affects to the productivity of workers. Accumulation of radon is one of the most publicized indoor air pollution problems in
some areas. Radon and its radioactive daughters are known carcinogens and may be the
second leading cause of lung cancer after smoking. Among the following radioactive
elements formed as radon decays which one causes the greatest lung damage: (a)
uranium, (b) radium, (c) polonium, or (d) lead. Skies are generally clear when a high pressure zone arrives. Which of the following
related statements is false: (a) temperature tends to increase as high pressure air sink to
the land surface, (b) relative humidity tends to decrease as high pressure air sink to the
land surface, (0) heavy rain accompanied by the arrival of high pressure tends to clean up
the surface air, or (d) the arrival of high pressure causes vertical air movement. Cyclone is a very cost effective device for air pollution control. Its efﬁciency is relatively
independent of: (a) particle size, (b) temperature, (c) particle density, or (d) air velocity.
Which of the following greenhouse gases has the highest radioactive forcing (as
measured in W/mz): (a) methane, (b) carbon dioxide, (c) halocarbons, or (d) nitrous oxide.
There are four sources of noise with respective levels of 68, 75, 79 and 84 db. What is the combined level of these four noises: (a) 86 db, (b) 93 db, (c) 153 db, or (d) 223 db. - END OF PAPER - ...
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This note was uploaded on 10/02/2010 for the course CIVIL ENGI 09332005 taught by Professor Kaiminshi during the Spring '10 term at Hong Kong Baptist University, China.
- Spring '10
- Environmental Engineering