ENV4204 S1 2014 Assignment Weighting 30% of the course (300 marks) Submission requirement One pdf report One excel spreadsheet (2 worksheets) Important notes a) It is expected that you will use a word processor to produce your report, and submit it in pdf format. You should use a spreadsheet (MS Excel) for the complex calculations that involve modelling, and submit the worksheet together with your report for verification. b) This course uses electronic submission through the EASE facility, which is located on the Study Desk. The individual file name(s) should include your surname, initials, and course ID, for example “Brown_JA_ENV4204.pdf” or “Brown_JA_ENV4204.xls. Warning about plagiarism Plagiarism detection software may be used to check your assignment. You will be severely penalised if it is found that you have copied verbatim from the work of other authors, including from web sites. You may quote the work of others but quotations should be used sparingly. For each question, quotations should amount to no more than 5 per cent of the specified word limit for that question, and each quotation must be cited correctly. To answer the assignment questions you are expected to consult your study package and other sources. However, the work you submit as your own work has to be in your own words. You are encouraged to discuss the concepts covered in the assignment questions with your classmates and others, but you should not release your written responses to the questions to anyone except the University. Students submitting a section or sections of assignment work which is the same as other students’ work will be severely penalised. Further information about plagiarism can be found on the University website. TASKS (9) 1) Water chemistry 1 (10 marks) Calculate the gram molecular weight of glucose (C6H12O6). How many grams of oxygen would it take to oxidise 570g of glucose? If you add 1kg of glucose to one litre of water, what is the molar concentration? 2) Water chemistry 2 (10 marks) In a groundwater were analysed: 150 mg/L of calcium ions and 10 mg/L of sodium ions. a) Express these concentrations in mmol/L and in meq/L. b) Calculate the concentration of sodium ions for the case that all calcium ions have been replaced by sodium ions during rock-water interactions (in mg/L, mmol/L and meq/L). 3) Water chemistry 3 (15 marks) A solid solution of Ca-MgCO3 contains 5% (by weight) of Mg. a) Calculate the mole fraction of MgCO3 in the solid solution (the mole fraction of a substance c in a solution is the quotient between molar concentration and total molar concentration). 4) Water chemistry 4 (15 marks) A water with a calcium concentration of (Ca2+) = 80 mg/L is in contact with the mineral fluorite (CaF2). Calculate the solubility of fluorite at a temperature T=25°C. pKs of fluorite is 10.96 at 25°C. 5) Water chemistry 5 (40 marks) 5) The density of saline water has a density of 1.2 kg/L a 25°C. The saline water contains 100,000 mg/kg (ppm) of sodium. a) Express this sodium concentration in mg/L. b) Now the saline water is heated to 100°C. At this temperature, 1 kg of the saline water has a volumen of 0.84 L. Calculate the sodium concentration (in mg/L) at this temperature. 6) Degradation rate calculation (15 marks) At intervals of two days the concentration of nitrogenous waste in a bioreactor is 85, 73, 62, 54, 46 and 39 mg/L. What is the reaction rate constant (k d-1) ? 7) Streeter-Phelps calculation (70 marks) Set up an excel spreadsheet to calculate DO critical concentration and distance. Produce a plot of the Streeter-Phelps DP sag curve. Use the following parameters :- Parameter Wastewater Creek at discharge location Flowrate 25m3 per day 250m3 per day BOD5 at 20°C 200 mg/L BOD ultimate 5 mg/L DO 0.5 mg/L 9.35 mg/L Temperature 28°C 19°C Deoxygenation rate constant, kd 0.1 d-1 Reaeration rate constant, kr 0.2 d-1 River bed activity coefficient 0.15 Due to a major upgrade project, an industrial plant is seeking permission to discharge partially treated wastewater into a river over a limited period. Estimate the expected impact river using the StreeterPhelps model. Answer the following: 1) What is the expected critical DO concentration? 2) What is the expected distance of the critical location? 3) What is the discharge rate of the wastewater to maintain at least 5 mg/L critical DO concentration in the river? 8) Packed Tower Design Calculation (35 marks) Determine the required height of a 3 m diameter packed tower required to remove 0.4 mg/L acetone in contaminated water. Assume water flow is 10 m3 /s, Henry’s Law constant is 5.0 x 10-4 atm.m3 /mol, KLa is 10 x 10-3 s -1, air flowrate is 15 m3 /s, liquid flowrate is 0.07 m3 /s and temperature is 22°C. 9) Gaussian Dispersion Problem (90 marks) Air pollution from factories located in China is now causing a serious health concern for Chinese residents. As atmospheric stability increases, so pollution plume concentrations at ground level can increase. As the number of factories continues to increase, air pollution levels also increase. As an environmental consultant you are required to do some modelling of this problem using Excel spreadsheet and the Gaussian Dispersion method. You are expected to summarise your findings in a short 1000 word report for the Asian Health Organisation. In your report: i. Carry out some research on typical air pollution levels experienced by people living in in China, and use this as a basis for writing an introduction explaining the background to your report ii. Do some research to find out what the typical air pollutants are, from a particular industry of your choice. Do some research on health effects of the pollutant and its human TWA No Effect Level (NOEL) via inhalation. iii. Develop a spreadsheet model/program to predict a typical ground level centreline concentration of odour (in µg/m3 ) from a single factory with a release stack 20 m high. Get your model to produce graphs of average centre-line ground level concentration, versus distance in kilometres downwind of the factory. Assume a windspeed of 2 m/s and E class stability iv. Do some modelling to explain the effect of adding additional identical factories, placed at 1km centres on a grid, upwind, and to either sides of the mean wind direction, from the initial factory which you considered in part iii. v. In your report, clearly show your assumptions, calculation method and your main findings. Rely on your report to do this, as your spreadsheet will only be looked at briefly. vi. Carry out some additional research on the Gaussian method and other modelling approaches, and include in the conclusion to your report the strengths and weaknesses of using the Gaussian approach to solving this kind of problem. Figure 1 Conceptual diagram to assist with part iv) – hint – you can use the line source variant of the Gaussian dispersion equation
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