Environmental Engineering

Learning Objectives 1- Get Familiar with the operation of a continuous flow ion-exchange contactor (column) to remove the contaminant nitrate from water. 2-cTo experimentally determine two important ion exchange operating parameters: breakthrough curve and column utilization. 3- To familiarize students with common contaminants removed by ion-exchange and the issue of regenerant disposal.

1. Polychlorinated biphenyls (PCBs) are a widespread sediment contaminant. To sequester this contaminant, an "active cap" consisting of an adsorbent material can be used (Fig. 1). A study was published in 2006 by Murphy et al. to compare the performance of different types of cap material: sand, coke, and activated carbon. (a) Plot in Excel or another spreadsheet software the breakthrough curve for Cout(t)/Cin vs. t exiting the 1.25 cm capping layer, if there is no degradation (see next page for example spreadsheet setup). The range on the time axis for your plot should be selected to clearly observe when complete breakthrough has occurred - note the time scales may be extremely different (by several orders of magnitude) for the three different capping materials; therefore, prepare three separate plots for sand, coke, and activated carbon. Write a sentence explaining the differences in the time to breakthrough for the three materials, in terms of the advection-dispersion-adsorption parameters in Table 1. (b) Repeat part (a) if PCB has a half-life of 50 years and undergoes 1st order decay (biodegradation) in the capping layers. Plot the Cout(t)/Cin vs. t results onto the same plot that you made in part (a) for each capping material. Write a sentence explaining the trend in the final (steady-state) concentration that exits the capping layer for the three different materials when the degradation reaction is included.

2. An air pollution source emits a nonreactive pollutant at a rate of 500 g/s from a stack height of 125 m during a clear night. The plume rise is 75 m. The wind speed is 4 m/s as measured by an anemometer at 10 m height. Use Briggs urban dispersion coefficients and rough terrain. (a) Estimate ground level concentrations in µg/m³ at a distance 4000 m downwind of the source and 50 m orthogonal to the plume centerline (i.e., x = 4000 m, y = 50 m). Assume the dispersion is unbounded at both the ground and above. For this part of the problem, perform the calculations by hand (to practice for an exam scenario). (b) Set up in Excel or another spreadhseet program to compute the ground level concentrations in µg/m³ for the same scenario as part (a) at downwind distances x of [100, 200, 300, ...... 10000] m from the source. When setting up the spreadsheet, you should have columns for x, Oy, G, and C(x.y.z). (c) Compute the ground level concentrations in µg/m³ at x from 100 to 10000 m, assuming the pollutant is perfectly reflected from the ground and unbounded from above. (d) Compute the ground level concentrations in µg/m³ at x from 100 to 10000 m, assuming a fumigation scenario with an inversion height z; of 400 m. (e) Plot all scenarios (b, c, d) on the same graph. Explain the differences between the three concentrations based on the physical description of the model. Discuss which scenario would be the most hazardous.

For a soil sample received in your lab, the fraction of organic carbon has been reported to be 0.15. You have done two isotherm experiments and you have obtained the following results: Test 1: Aqueous-phase concentration 0.30 [µg/kg] and solid-phase concentration: 0.360 [µg/kg] Test 2: Aqueous-phase concentration:0.20 [ug/kg] and solid-phase concentration: 0.240 [μg/kg]

A well-mixed lake with a surface area of 6.0 [Km^2] and an average depth of 10 m is fed by a stream and rainfall. (Groundwater and runoff are insignificant inputs). The stream's flow rate is 1 [m^3/s], and the concentration of phosphorous in the stream is 1 [mg/l]. Average rainfall is 1 [m/yr], and the rain has a phosphorous concentration of 0.01 [mg/l]. Phosphorous removal by evaporation and by biological processes is negligible. Phosphorous precipitates from the lake's water according to first-order kinetics, with a rate constant of 0.005/d. The outlet stream has a flow rate of 0.2 [m^3/s], which keeps the volume of water in the lake essentially constant. The concentration of phosphorous in the lake is most nearly?

Problem 10. Let's slightly adjust Problem 5 again. Redo problem 5 if SO2 is not conservative and in fact degrades at 0.23/hr; calculate its steady state concentration over the city. (The input and windspeed are still the same).

Figure P 5.6 shows a plot of BOD remaining versus time for a sample of effluent taken from a wastewater treatment plant. (a) What is the ultimate BOD (L)? (b) What is the five-day BOD? (c) What is L5?

03) Which of the following demonstrates the greatest stewardship in addressing the production and disposal of MSW? promote strategies that reduce the generation of MSW compost organic components of MSW recycle MSW as much as possible promote strategies that reduce MSW, compost organic components, and recycle as much MSW aspossible

16. CVEN 3401: A completely mixed continuous bioreactor used for growing penicillin operates as a zero order system. The input, glucose, is converted to various organic yeasts. The flow rate to this system is 20 L/min, and the conversion rate constant is 4 mg/(min-L). The influent glucose concentration is 800 mg/L, and the effluent must be less than 100 mg/L. What is the smallest reactor capable of producing this conversion?

Problem 4. Using the following estimates for the US and assuming that growth rates remain constant. A. Find the carbon emission rate in 2020. B. Find the total carbon emitted during those 30 years. C. Find the total energy demand in 2020. D. Find the per capita carbon emissions in 2020.