Home › Previous year questions › GATE 2024 ES › Question 17GATE 2024 ES – Question 17 Water and Wastewater Treatment and Management · Sewage Collection and Treatment · 1 mark · Multiple choice
Crown corrosion in reinforced-concrete sewers is caused by
Sulfur-oxidizing bacteria Iron-oxidizing bacteria Denitrifying bacteria Fermentative bacteria Practise this question in The GATE Grind →
Show answer and explanation Correct answer: (A) Sulfur-oxidizing bacteria
Explanation Hydrogen sulfide released from sewage can reach the moist sewer crown. Sulfur-oxidizing organisms convert reduced sulfur to sulfuric acid, which attacks concrete and can expose reinforcement. Thus the organisms directly associated with this crown-acid corrosion are **A**.
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