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GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER-VI (NEW) EXAMINATION - WINTER 2020
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Subject Code:2161304 Date:22/01/2021
Subject Name:Biological Processes for Wastewater Treatment
Time:02:00 PM TO 04:00 PM Total Marks: 56
Instructions:
- Attempt any FOUR questions out of EIGHT questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
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Marks
Q.1 (a) Differentiate between Biological and Physicochemical analysis 03
(b) Explain clearly the difference between BOD, COD and TOC. 04
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(c) Derive the relationship to find the amount of methane per gram of 07 COD.
Q.2 (a) Define the terms: (i) SVI (ii) organic loading (iii) yield coefficient 03
(b) A sample of wastewater was incubated for 7 days at 20 °Cand BOD result is 208 mg/l, BOD rate constant K = 0.15 day-1. Calculate (i) 5 —day BOD (ii) 10 — Day BOD (iii) Ultimate BOD 04
(c) Explain mass balance for substrate for CFSTR with recycle. 07
Q.3 (a) Explain about stuck reactor. 03
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(b) With reference to attached/growth processes explain mass transfer limitations. 04
(c) Explain the Thomas method for determination of reaction rate constant and ultimate BOD. 07
Q.4 (a) Explain the role of microorganism in wastewater treatment? 03
(b) Give classification of biological treatment processes. 04
(c) Compute the mean cell residence time, recirculation ratio, and volume of a reactor from the following data to design a conventional activated sludge process. Compare the recirculation ratio if the effluent biomass concentration of 15 mg/L is considered in the mass balance analysis. Given data: ¢ Daily average wastewater flow, Qavg = 20 MLD ¢ Sludge wasting flow, Qw = 140 m3/d « Biomass concentration in reactor, X = 4000 mg/L sludge retention time, θ = 4 hours 07
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Q.5 (a) Differentiate between Anoxic and Anaerobic process. 03
(b) Write the Difference Between Aerobic & Anaerobic Treatment Process. 04
(c) Enlist the modifications of Activated sludge Process and explain any two with sketch. 07
Q.6 (a) Discuss the problems of bulking in ASP 03
(b) Enlist the parameters affecting anaerobic digestion and explain alkalinity requirement. 04
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(c) Explain anaerobic treatment process as a four stage process. 07
Q.7 (a) Discuss about multistage anoxic digester. 03
(b) Explain single stage and two stage trickling filter. 04
(c) Write a short note on systems with packaged (pre-engineered) treatment plants. 07
Q.8 (a) Write a brief note on slow sand filter: 03
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(b) Discuss the mechanism of working of RBC with neat sketch. 04
(c) Explain the major problems faced by small communities to treat the domestic wastewater 07
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