The Secondary treatment of sewage is carried out by the use of
- AScreens
- BGrit chambers
- CTrickling filtersCorrect
- DNone of the above
Solution
Concept
Secondary treatment methods in sewage processing
Formula
NONE
Step-by-step solution
1. Primary wastewater treatment relies on physical operations like screening and grit removal to settle solids. 2. Secondary treatment utilizes biological processes to decompose dissolved and colloidal organic matter. 3. Trickling filters are attached-growth biological units specifically used for secondary sewage treatment. Answer: C
Explanation
Secondary treatment of wastewater focuses on removing dissolved and colloidal organic matter using biological processes. Trickling filters utilize aerobic microorganisms attached to a bed of coarse media to break down organic contaminants in sewage. Conversely, screens and grit chambers belong to the preliminary and primary treatment stages.
Why the other options are wrong
A) Screens are used in preliminary treatment to remove large floating solids. B) Grit chambers are used in preliminary treatment to remove inorganic grit and sand. D) Option C is correct because trickling filters provide secondary biological treatment.
Shortcut
Primary treatment is physical (screens, grit chambers); Secondary treatment is biological (trickling filters).
Common mistake
Confusing secondary biological treatment processes like trickling filters with primary physical screening or grit removal operations.
Correct answer: C) Trickling filters