Dissolved Oxygen in Treated Sewage

This text is a multiple choice question from the book “Civil Engineering” by Sandeep Jyani. The question asks which of the following statements is correct about the dissolved oxygen (DO) content of treated sewage. The correct answer is d) All the above.

Here are the questions and answers:

• In treated sewage, what is the essential level of DO?
• Only very fresh sewage contains some dissolved oxygen. True or false?
• The solubility of oxygen in sewage is 95% that is in distilled water. True or false?

The answers are:

• 4 PPM
• True
• True