The characteristics of fresh and septic sewage respectively are A. Acidic and alkaline B. Alkaline and acidic C. Both acidic D. Both alkaline

The correct answer is A. Acidic and alkaline.

Fresh sewage is acidic because it contains a high concentration of organic matter, such as food waste and human waste. This organic matter is broken down by bacteria, which produce acids as a byproduct. Septic sewage is alkaline because it contains a high concentration of ammonia, which is a base. Ammonia is produced when bacteria break down urea, which is a waste product of protein metabolism.

Here is a brief explanation of each option:

• Option A: Acidic and alkaline. This is the correct answer. Fresh sewage is acidic because it contains a high concentration of organic matter, such as food waste and human waste. This organic matter is broken down by bacteria, which produce acids as a byproduct. Septic sewage is alkaline because it contains a high concentration of ammonia, which is a base. Ammonia is produced when bacteria break down urea, which is a waste product of protein metabolism.
• Option B: Alkaline and acidic. This is not the correct answer. Fresh sewage is acidic, while septic sewage is alkaline.
• Option C: Both acidic. This is not the correct answer. Fresh sewage is acidic, while septic sewage is alkaline.
• Option D: Both alkaline. This is not the correct answer. Fresh sewage is acidic, while septic sewage is alkaline.