More Questions from Waste Water Engineering

In wastewater oxidation processes (natural or engineered), which compounds are typically formed as the end products of oxidizing organics and reduced species?

Civil Engineering Waste Water Engineering Difficulty: Easy
Choose an option
  • A
    Carbon dioxide (from carbonaceous oxidation)
  • B
    Nitrates (from nitrification of ammonia)
  • C
    Sulphates (from oxidation of sulphides)
  • D
    All the above
  • E
    None of the above

Answer

Correct Answer: All the above

Explanation

Introduction / Context:Biochemical and chemical oxidation in wastewater treatment converts reduced compounds into more oxidized, stable forms. Recognizing the typical products helps in interpreting plant performance and effluent characteristics.

Given Data / Assumptions:

  • Presence of organic carbon, ammonia, and sulfide species in sewage.
  • Oxidation can be biological (aerobic) or chemical (e.g., with oxidants).
  • Complete oxidation end products considered.

Concept / Approach:

Carbon in organics is oxidized to carbon dioxide; ammonia is converted to nitrite and then nitrate (nitrification); sulfides/sulfur are oxidized to sulfate. These transformations lower BOD and toxic odors and stabilize the wastewater.

Step-by-Step Solution:

Carbonaceous oxidation → CO2 and water.Autotrophic nitrifiers oxidize NH3 → NO2- → NO3-.Sulfur species (H2S, S2-) oxidize to SO4^2-.

Verification / Alternative check:

Stoichiometric equations and process monitoring (CO2 evolution, nitrate increase, reduction in sulfide odors) support these end products.

Why Other Options Are Wrong:

Each individual option describes a real oxidation product; therefore the aggregate choice (all the above) is correct.

Common Pitfalls:

Confusing denitrification (which reduces nitrate to nitrogen gas) with oxidation; ignoring partial oxidation intermediates.

Final Answer:

All the above

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