Final answer:
Incineration is not a step in the wastewater treatment process; it is a method of sewage sludge disposal. The treatment process typically involves preliminary, primary, secondary, and tertiary phases. Therefore, correct option is c.
Step-by-step explanation:
The answer to the student’s question, “Which one of the following is NOT a step in wastewater treatment?” is c. Incineration.
Wastewater treatment involves several steps but incineration is not typically a part of the liquid wastewater treatment process. Instead, wastewater and sewage is treated in three main phases:
- Preliminary treatment processes which involve screening and removal of sand and gravel.
- Primary (physical) treatment focuses on settling or floatation to remove organic solids, fat, and grease.
- Secondary (biological) treatment includes aerobic bacterial decomposition of organic solids.
- Tertiary treatment involves further bacterial decomposition of nutrients, sand filtration, and disinfection before discharge or reuse.
Incineration, however, may be used to dispose of sewage sludge – the byproduct of primary and secondary treatment – but is not a step in the direct treatment of wastewater.