Secondary Treatment (Biological Treatment) of Sewage
Biological degradation of organic matter in sewage by aerobic microbes in large aeration tanks.
What is Secondary Treatment (Biological Treatment) of Sewage?
The amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period.
Key points
- Explain the purpose of secondary sewage treatment.
- Identify the types of microorganisms involved.
- Describe the process of aerobic decomposition of organic matter.
- Understand the role of aeration and flocs formation.
Common exam trap
Confusing secondary treatment with primary treatment (physical separation).
Definitions
- Term
Biochemical Oxygen Demand (BOD)
- Meaning
The amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period.
- Term
Aerobic Microorganisms
- Meaning
Microorganisms that require oxygen for their metabolic activities and growth.
- Term
Flocs
- Meaning
Aggregates or clumps formed by microbial growth, often used in wastewater treatment for settling out impurities.
Learning objectives
Explain the purpose of secondary sewage treatment.
Identify the types of microorganisms involved.
Describe the process of aerobic decomposition of organic matter.
Understand the role of aeration and flocs formation.
Differentiate secondary treatment from primary treatment.
Prerequisites
Understanding of primary sewage treatment.
Basic knowledge of microorganisms and their role in decomposition.
Concept of aerobic respiration.
Common mistakes
Confusing secondary treatment with primary treatment (physical separation).
Forgetting the role of oxygen in aerobic decomposition.
Not understanding the concept of BOD reduction as the main objective.
Keywords
Sewage treatment
Secondary treatment
Biological treatment
Aerobic decomposition
BOD
Aeration tank
Activated sludge process
Microorganisms
Flocs
Practice preview
Which type of microorganisms are predominantly utilized in the secondary treatment of sewage?…
easy
The process of secondary sewage treatment is also referred to as:…
easy
Activated sludge process is a type of:…
easy