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CEE 350 - Korshin - Winter 2012 - Practice Final(1)

# CEE 350 - Korshin - Winter 2012 - Practice Final(1) - CLASS...

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1 CLASS 350 FINAL PRACTICE EXAM Problem 1 Define the following abbreviations AQI Air Quality Index DNAPL Dense Non-Aqueous Phase Liquid LNAPL Light Non-Aqueous Phase Liquid NAAQS National Ambient Air Quality Standards MCL Maximum Contaminant Level Problem 2 Name three major technologies for post-combustion removal of particulates from flue gases generated in coal-fired power plants? These are (A) Cyclone collectors; (B) Electrostatic precipitators and (C) Bag houses Problem 3 List six criteria pollutants established by National Ambient Air Quality Standards? These pollutants are carbon monoxide, lead, NOx, SOx, ground-level ozone, PM 10 and PM 2.5 (the last two are counted as one category). Problem 4 Calculate the percentage of carboxyhemoglobin (COHb) in the blood of a person exposed to 70 ppm CO during 30 minutes. Will any health effects be possible for these conditions? This can be calculated using the formula shown below: ± ² ± ² > @ CO t COHb u u ³ ³ u 402 . 0 exp 1 15 . 0 % For conditions given in the problem, the percentage of COHb will be ± ² ± ² ± ² % 9 . 1 82 . 0 1 5 . 10 70 5 . 0 402 . 0 exp 1 15 . 0 % ³ u u u ³ ³ u COHb This level of COHb is unlikely to cause any health problems. Problem 5 Groundwater containing 75 μg/L arsenic is coagulated with FeCl 3 to remove that arsenic to a 10 μg/L level. The optimal dose has been determined to be at 120 mg/L FeCl 3 . Calculate the weigh concentration of arsenic in the sludge. Determine whether it will need to be sent to a hazardous waste landfill if its concentration exceeds the threshold of 1 g As per kg sludge produced. The amount of solid produced by treatment of each liter of water is ± ² ± ² ± ² L mg MW MW M M FeCl OH Fe FeCl OH Fe / 79 3 5 . 35 8 . 55 3 17 8 . 55 120 3 3 3 3 ) ( ) ( u ´ u ´ u The amount of arsenic retained by this sludge will be

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2 ± ² ± ² ± ² L mg As As M out in As / 065 . 0 010 . 0 075 . 0 ³ ³ The weight concentration of arsenic in the sludge is therefore 0008 . 0 79 065 . 0 3 ) ( OH Fe As As M M W This number corresponds to 0.8 g of arsenic per 1 kg of sludge. This is slightly below the stated threshold, and the sludge will not need to be sent to a hazardous waste landfill. Problem 6 Water from a stream containing 120 μg/L of phosphorus enters a small lake with surface area 40,000 m 2 and volume 200,000 m 3 . The flow rate of the stream is 20,000 m 3 /day. Virtually all phosphorus in the stream is bound on the surface of nearly-spherical mineral particles. The density of the particles is 1.8 and their average diameter is 5 μm. Presuming that the lake is completely mixed and phosphorus in the lake is lost due to the settling of the mineral particles, determine the concentration of phosphorus in the effluent from the lake. Also determine whether the lake is expected to be in oligotrophic, mesotrophic or eutrophic state (presuming that phosphorus is the limiting nutrient).
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