waste water engineering

3
CHMT4013 Assignment 2 The following are real data measured from a bioreactor which is being used to process a waste stream. The reactor kinetics are unknown and you are required to determine a rate constant for the degradation of the COD. An impulse-response tracer study was done on the reactor to determine what type of reactor is being considered and the rates of contaminant degradation need to be found. The effluent is from a starch manufacturing facility and due to its high COD cannot be discharged directly to sewer and must therefore be pre-treated by a biodigestor on site. The average starch concentration is 63g/L and the average COD of the effluent is 40g/L. In Table 1 data is shown where we used an inert tracer to conduct an impulse-response experiment. Table 1. Impulse response tracer experiment data. Time (min) Concentra tion (mg/l) 0 0.0000 10 0.0000 15 0.9965 20 2.6676 22.5 3.5911 25 3.5052 27.5 3.1659 30 2.8652 32.5 2.5516 35 2.2895 37.5 1.9759 40 1.7096 45 1.2715 50 0.9708 55 0.7173 60 0.5111 65 0.3822 70 0.2877 75 0.3307 90 0.3100 105 0.2580 120 0.2040 140 0.1010

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CHMT4013 Assignment 2The following are real data measured from a bioreactor which is being used to process a waste stream. The reactor kinetics are unknown and you are required to determine a rate constant for the degradation of the COD. An impulse-response tracer study was done on the reactor to determine what type of reactor is being considered and the rates of contaminant degradation need to be found. The effluent is from a starch manufacturing facility and due to its high COD cannot be discharged directly to sewer and must therefore be pre-treated by a biodigestor on site. The average starch concentration is 63g/L and the average COD of the effluent is 40g/L.In Table 1 data is shown where we used an inert tracer to conduct an impulse-response experiment. Table 1. Impulse response tracer experiment data.Time (min)Concentration (mg/l)

00.0000

100.0000

150.9965

202.6676

22.53.5911

253.5052

27.53.1659

302.8652

32.52.5516

352.2895

37.51.9759

401.7096

451.2715

500.9708

550.7173

600.5111

650.3822

700.2877

750.3307

900.3100

1050.2580

1200.2040

1400.1010

1600.0059

1800.0000

You are required to calculate the following (Refer to Levenspiel or Fogler for this theory).1. You will need to draw a C vs t graph[2]

2. You will need to plot an E vs t graph[5]

3. You need to find the mean of the residence time distribution [10]

4. Assume the reactor can be modelled as a tanks-in series reactor. Find a value for N, by calculating the second moment of the distribution (i.e. )[3]

5. Discuss what you found in Q3 relative to the ideal residence time which hasA value of 1.2 hours. Postulate reasons for any difference based on yourunderstanding of the residence time distribution[5]

6. Assuming that starch can be modelled as glucose, for a starting concentration of 63g/L, find the equivalent COD.[5]

7. If the final concentration of starch is 0.103g/L after treating with the bioreactor, what is the rate constant of degradation if you assume first orderkinetics? (Hint, Round N up to the nearest number and solve the TIS eqtn)[5]

8. The final COD of the effluent prior to discharge is 500mg/L. Calculate the rate ofCOD removal.[5]

9. Discuss why the rates of degradation are different as well as why the ratioOf COD to starch is vastly different in the raw effluent to the discharge.[5]