The GATE Grind

GATE 2026 ES – Question 30

Water and Wastewater Treatment and Management · Water and Wastewater Quality · 1 mark · Multiple select

Total Kjeldahl Nitrogen includes which forms of nitrogen? Select all that apply.

  1. Ammoniacal nitrogen
  2. Nitrite nitrogen
  3. Nitrate nitrogen
  4. Organic nitrogen

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Show answer and explanation

Correct answer: (A) Ammoniacal nitrogen; (D) Organic nitrogen

Explanation

Kjeldahl digestion measures organic nitrogen after conversion to ammonium, together with ammoniacal nitrogen already present. Conventional TKN excludes oxidized nitrite and nitrate nitrogen. Thus TKN is organic plus ammoniacal nitrogen, and the correct selections are **A, D**.

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