CE-702-B Environmental Engineering-II - Jun 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 6 Marks
   aEnumerate various unit operations/processes and treatment systems used to remove major contaminant of waste water.
   How to answer

   • Define wastewater contaminants: suspended, colloidal, dissolved organics, nutrients, pathogens, etc.
   • List preliminary, primary, secondary (biological) and tertiary unit operations/processes
   • Match major contaminant to treatment system with examples
   • Brief flow-sheet of typical treatment train
2. 8 Marks
   bDifferentiate clearly between attached growth processes and suspended growth processes. List various treatment techniques falling under each such process.
   How to answer

   • Define attached growth vs suspended growth concept
   • Differentiate on basis of biomass, reactor, loading, maintenance
   • List attached growth techniques: trickling filter, RBC, contact bed etc.
   • List suspended growth techniques: ASP, oxidation pond, SBR etc.
3. 6 Marks
   aDiscuss in brief various types of settling tanks.
   How to answer

   • Define settling and purpose in primary/secondary treatment
   • Classify by flow: horizontal, vertical, radial; by function: primary, secondary
   • Brief features of each type with sketch concept
   • Selection criteria
4. 8 Marks
   bThe effluent from a primary settling tank is applied to a standard rate filter at the rate of 3 million liters per day, having a $BOD_5$ of 175 mg/l. Determine the depth and volume of filter, adopting a surface loading of 2000 l/m$^2$/day and an organic loading of 150 g/m$^2$/day. Also determine the efficiency of such filter unit, using NRC formula.
   How to answer

   • Compute surface area from hydraulic loading and organic loading, adopt larger
   • Compute volume and depth from loadings
   • Compute organic load applied and NRC efficiency formula $E = 100/[1+0.0044\sqrt{U}]$
   • Report depth, volume and efficiency
5. 14 Marks
   The MLSS concentration in an aeration tank of activated sludge process is 2500 mg/lit and the sludge volume after 30 minutes of settling in a 1000 ml graduated cylinder is 180 ml. Determine:

   1. i)SVI
   2. ii)return sludge ratio required and
   3. iii)SS concentration in the return sludge.
   How to answer

   • Define SVI = settled volume (ml/l) x 1000 / MLSS (mg/l)
   • Calculate SVI from 180 ml per 1000 ml and 2500 mg/l
   • Relate return sludge ratio to SVI/MLSS and estimate Xr
   • Compute SS concentration in return sludge
6. 6 Marks
   aWhat is meant by sludge recycle? How do you determine the sludge, recycle rate if SVI and MLSS concentration in the reactor are known?
   How to answer

   • Define sludge recycle/recirculation purpose
   • Explain need to maintain MLSS and biomass
   • Derive recycle ratio formula using SVI and MLSS
   • Steps with mass balance example
7. 8 Marks
   bWhat do you understand by a 'contact bed'? Explain various operations of its working.
   How to answer

   • Define contact bed as attached growth unit
   • Describe construction: media, dosing, resting
   • Explain cycle of operation: filling, contact, draining, resting
   • Merits/limitations
8. 6 Marks
   aDescribe the method of adsorption by activated carbon. How granular carbon is regenerated.
   How to answer

   • Principle of adsorption on activated carbon
   • Types: powdered vs granular, contact systems
   • Regeneration methods: thermal, steam, chemical
   • Applications in tertiary treatment
9. 8 Marks
   bDiscuss in brief the biological and chemical methods of removal of phosphorous from waste water.
   How to answer

   • Sources and forms of phosphorus in wastewater
   • Biological removal: luxury uptake, A/O, A2O process
   • Chemical removal: precipitation with alum, lime, iron salts
   • Comparison and sludge handling
10. 6 Marks
    aWhat is meant by Smog? Discuss its causes and effects.
    How to answer

    • Define smog: smoke + fog, types photochemical and classical
    • Causes: vehicular, industrial emissions, meteorology
    • Effects on health, visibility, materials, plants
11. 8 Marks
    bEnumerate the different major air pollutants, their characteristics, sources and health effects on human beings in a tabular form.
    How to answer

    • List major pollutants: SPM, SO2, NOx, CO, HC, O3
    • Tabulate characteristics, sources for each
    • Health effects on humans
    • Standards/reference values
12. 6 Marks
    aWhat do you understand by atmospheric dispersion? Write down the equation for determining ground level concentration of pollutant.
    How to answer

    • Define atmospheric dispersion and plume behavior
    • Factors: wind, stability, stack height
    • Present Gaussian plume equation for ground level concentration
    • Explain terms: Q, u, sigma-y, sigma-z, H
13. 8 Marks
    bA coal fired 800 MW power plant is operating around 38% efficiency. The ash and sulphur content in the coal used respectively are 38% and 4%, and the calorific value of 21 MJ per kg of coal. Find the emission rate of $SO_2$ from the plant.
    How to answer

    • Compute heat input = power / efficiency
    • Compute coal consumption = heat input / calorific value
    • Sulphur mass to SO2 mass using 64/32 factor
    • Compute emission rate in kg/s or tonnes/day
14. 14 Marks
    Write short notes on (any four):

    1. i)Role of micro-organisms in waste water treatment
    2. ii)Factors affecting the dispersion of air pollutants
    3. iii)Causes and effects of inversion
    4. iv)Stationary and mobile sources of air pollutants
    5. v)Ultrafiltration
    6. vi)Adsorption by activated carbon
    How to answer

    • Select any four topics from i-vi
    • Give definition, principle and relevance for each
    • Add applications / factors / effects as applicable
    • Conclude with significance in environmental engineering