Question

Select the colloidal material in domestic sewage :

• A. Faecal matter, Bacteria, cloth and paper fibres
• B. Garbage
• C. Sand, Silt and Clay
• D. Nitrate, ammonia, phosphate

Answer 1

The correct option is A Faecal matter, Bacteria, cloth and paper fibres

Domestic sewage contains four kind of impurities –
(i) Suspended solids: They are soil particles such as sand and silt.
(ii)Colloidal particles: They are inorganic and organic materials such as faecal matter, bacteria, paper and cloth.
(iii)Dissolved solids: They are nitrates, phosphates, ammonia, sodium, calcium and other nutrients.
(iv)Pathogens: Domestic sewage has pathogens of various diseases such as typhoid, cholera, dysentery etc.

So, the correct answer is "option D"