CE 403 Optional FE Review: Environmental engineering Chris Rehmann Environmental engineering A. B. C. D. E. Water quality (ground and surface) Basic tests (e.g., water, wastewater, air) Environmental regulations Water supply and treatment Wastewater collection and treatment Water quality: Example 1 The world population was about 4 billion in 1975 and 6 billion in 1999. If the growth is exponential, then in 2020 the population in billions will be most nearly A. B. C. D. 8 10 11 15 Water quality: Example 2 A contaminant is injected uniformly into a tank of volume 5 L. The contaminant follows a first-order reaction with decay rate 0.21 d-1. The time in days until the concentration is half the initial concentration is A. B. C. D. 1.4 2.4 3.3 4.8 Water quality: Example 3 Micro-organisms are growing according to Monod kinetics. The maximum growth rate is 0.4 d-1. The substrate concentration is 25 mg/L, and the saturation constant is 50 mg/L. The ratio of the growth rate and maximum growth rate is most nearly A. B. C. D. 13% 33% 50% 100% Water quality: Example 4 A tributary with a discharge of 3 m3/s and nitrate concentration of 20 mg/L meets a river with a discharge of 30 m3/s and nitrate concentration of 4 mg/L . The concentration in mg/L downstream of the confluence is most nearly A. B. C. D. 5.5 12.0 18.2 24.0 Water quality: Example 5 Wastewater is discharged into a river with a mean velocity of 0.25 m/s. After initial mixing the dissolved oxygen concentration is 7.5 mg/L and the ultimate BOD is 40 mg/L. The reaeration coefficient is 0.4 d-1, and the deoxygenation coefficient is 0.2 d-1. The saturated DO concentration is 8.2 mg/L. The dissolved oxygen concentration (in mg/L) 5000 m downstream is most nearly A. B. C. D. 5.8 6.7 8.2 18.6 Adapted from example 8.1 of Tchobanoglous & Schroeder (1987) Water quality: Example 6 A river flows through a lake with a volume of 6x106 m3. The inflow and outflow are both 5 m3/s. The inflow has a contaminant with a concentration of 10 mg/L and a decay rate of 0.2 d-1. The steady state concentration of the outflow in mg/L is most nearly A. B. C. D. 0.7 2.7 8.3 10.0 Water quality: Example 7 A landfill has a clay liner with a thickness of 80 cm, a hydraulic conductivity of 10-7 cm/s, and a porosity of 30%. If the hydraulic head is 100 cm, then the time (in years) for leachate to break through the liner is most nearly A. B. C. D. 3.4 5.3 25.4 57.1 Water quality: Example 8 Benzene is leaking from an underground storage tank. The aquifer has an average linear velocity of 0.03 m/d, a bulk density of 2 g/cm3, and a porosity of 23%. If the distribution coefficient is 0.3 mL/g, the speed (in m/d) at which the flow advects the contaminant is most nearly A. B. C. D. 8.3x10-3 1.2x10-2 3.0x10-2 1.1x10-1 Basic tests: Example 9 Hexose is oxidized by the following reaction. What is the coefficient of hexose? ?? C6H12O6 + 6 O2 ?? CO2 + ?? H2O A. B. C. D. 1/6 1 6 12 Basic tests: Example 10 A solution has a molar concentration of hydrogen ions of 1.58x10-4 M. The pH is most nearly A. 0.2 B. 1.58 C. 3.8 D.4.0 Basic tests: T&S ex. 2.1a A 1-L solution contains 20 g of calcium carbonate (CaCO3). If the density of the calcium carbonate is 1.12 g/mL, then the molarity of the solution is most nearly A. 0.0002 M B. 0.0004 M C. 0.2M D. 0.4M Basic tests: T&S ex. 2.1b A 1-L solution contains 20 g of calcium carbonate (CaCO3). If the density of the calcium carbonate is 1.12 g/mL, then the mole fraction of the solution is most nearly A. 3.26x10-3 B. 3.65x10-3 C. 4.06x10-3 D. 2.00x10-1 Basic tests: Helmenstine ex. 1 Hydrogen gas (H2) and iodine gas (I2) react to form hydrogen iodide gas (HI). If the equilibrium constant at 25°C is 7.1x102 and the equilibrium concentrations of H2 and I2 are 0.81 M and 0.035 M, respectively, then the equilibrium concentration of HI is most nearly A. 0.05 B. 0.22 C. 4.49 D. 20.1 Basic tests: Example 11 The biochemical oxygen demand of a water sample was measured to be 140 mg/L at 5 d, and the ultimate BOD is 160 mg/L. The decay coefficient (in d-1) is most nearly A. B. C. D. 0.13 0.18 0.20 0.42 Basic tests: Example 12 A wastewater sample has ultimate BOD of 30 g/m3 and a rate coefficient of 0.22 d-1 at 20°C. If the temperature coefficient q is 1.056, then the ratio of the 5-d BOD at 25°C and the 5-d BOD at 20°C is most nearly A. 0.76 B. 0.87 C. 1.15 D. 1.31 Env. regulations: Example 13 Which of the following deals with permits for discharges to surface waters? A. B. C. D. Clean Water Act Safe Drinking Water Act National Environmental Policy Act Comprehensive Environmental Response, Compensation, and Liability Act Env. regulations: Example 14 Which of the following sets maximum contaminant levels for public drinking water supplies? A. B. C. D. Clean Water Act Safe Drinking Water Act National Environmental Policy Act Comprehensive Environmental Response, Compensation, and Liability Act Env. regulations: Example 15 Which of the following regulates the criteria pollutants: carbon monoxide, ozone, NOx, SOx, particulate matter, and lead? A. B. C. D. Clean Water Act Safe Drinking Water Act Clear Air Act National Environmental Policy Act Env. regulations: Example 16 Which of the following gave the Environmental Protection Agency the authority to regulate hazardous waste from “cradle to grave”? A. National Environmental Policy Act B. Comprehensive Environmental Response, Compensation, and Liability Act C. Affordable Care Act D. Resource Conservation and Recovery Act Env. regulations: Example 17 Which of the following is intended to clean the worst contaminated sites in the U.S.? A. National Environmental Policy Act B. Comprehensive Environmental Response, Compensation, and Liability Act C. Clean Water Act D. Resource Conservation and Recovery Act Water treatment: T&S ex. 12.4 The settling velocity in m/s of a sand particle (density = 2600 kg/m3) with diameter 0.5 mm in water at 20°C is most nearly A. B. C. D. 0.089 0.110 0.162 0.218 Water treatment: from T&S ex. 7.4 A batch adsorption test was conducted with 2 L samples of water with an organic contaminant at a concentration of 20 g/L. When 0.9 and 4 g of activated carbon is introduced, 14 and 28 g of contaminant is removed, respectively. If the adsorption follows a Freundlich isotherm, the mass in g of activated carbon needed to remove 34 g of contaminant is most nearly A. B. C. D. 5.3 6.2 9.9 12.6 Water treatment: Example 17 A granular medium filter has a 30-cm layer of uniform anthracite (porosity 35%, diameter 1.6 mm) over a 30-cm layer of uniform sand (porosity 40%, diameter 0.5 mm). The filtration rate is 0.002 m/s. The ratio of the head loss (computed by the CarmenKozeny equation) in the anthracite and the head loss in the sand is most nearly A. B. C. D. 0.30 0.31 0.49 1.00 WW treatment: Longhurst 1 Grit is mainly A. Inorganic material B. Organic material C. Total suspended solids D. Volatile solids See http://www.cram.com/flashcards/wastewater-test-quiz-331471 WW treatment: Longhurst 3 The main purpose of primary treatment is to remove A. Chlorine B. TSS and CBOD5 C. Ammonia D. Inorganic material See http://www.cram.com/flashcards/wastewater-test-quiz-331471 WW treatment: T&S 11.1 For primary sedimentation a circular tank is to be designed with a hydraulic detention time of 2.5 h and a surface overflow rate of 40 m3/m2·d for a town of 20,000 and wastewater flow of 0.45 m3/capita·d. The depth (in m) of the tank should be most nearly A. 1.5 B. 2.4 C. 3.3 D. 4.2 WW treatment: Example XX A wastewater treatment process treats 50,000 gal/d of sludge containing 2% solids. Thickening and dewatering reduces the volume of the sludge so that it has 25% solids. The reduction in volume in gal/d is most nearly A. 4,000 B. 37,500 C. 46,000 D. 49,000 Adapted from OnlineTechTraining.com