Exam Question
(a) Sketch and describe a biological sewage treatment system. (6)
(b) How does the biological Sewage Treatment Plant work? (6)
(c) What is understood by the term BOD? What factors that affect BOD (4)
Class 4 (4th Engineer)
MEKG
📅 Dec 2024
Reference Answer
### (a) Description of a Biological Sewage Treatment System
A biological sewage treatment system, as used on board ships, is a wastewater treatment process that utilizes naturally occurring aerobic microorganisms (primarily bacteria) to break down and decompose organic waste matter present in raw sewage. The fundamental principle is to create an ideal environment for these bacteria to thrive and efficiently digest the pollutants.
The system is typically a self-contained unit comprising several distinct compartments, each performing a specific function in the treatment process. The core of the system is the **extended aeration process**, where oxygen is continuously supplied to the sewage, promoting the growth of a dense population of aerobic bacteria. These bacteria consume the organic solids, converting them into carbon dioxide, water, and new bacterial cells, which form a biological mass known as **activated sludge**.
The main components of a typical system are:
A biological sewage treatment system, as used on board ships, is a wastewater treatment process that utilizes naturally occurring aerobic microorganisms (primarily bacteria) to break down and decompose organic waste matter present in raw sewage. The fundamental principle is to create an ideal environment for these bacteria to thrive and efficiently digest the pollutants.
The system is typically a self-contained unit comprising several distinct compartments, each performing a specific function in the treatment process. The core of the system is the **extended aeration process**, where oxygen is continuously supplied to the sewage, promoting the growth of a dense population of aerobic bacteria. These bacteria consume the organic solids, converting them into carbon dioxide, water, and new bacterial cells, which form a biological mass known as **activated sludge**.
The main components of a typical system are:
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