In long, sluggish-flow lines, biological activity is likely to cause which of the following conditions?

In long, sluggish-flow lines, biological activity is likely to cause which of the following conditions?

• A. All of the above
• B. Toxic gas production
• C. Oxygen deficiency in air
• D. Concrete and metal corrosion

Answer: (A)

In long, sluggish-flow sewer lines, conditions become low in dissolved oxygen, allowing anaerobic microbes to thrive. This biological activity consumes the available oxygen and generates gases such as hydrogen sulfide, which is toxic to humans and contributes to foul odors. The gas buildup and ongoing microbial respiration can also reduce the oxygen level in the air inside the pipe and manholes. At the same time, hydrogen sulfide and other byproducts can interact with pipe materials, with sulfuric acid formed on concrete surfaces leading to biogenic corrosion of concrete and, to some extent, metal corrosion. Because all of these effects can occur together in stagnant, long sewers, all of the above conditions are likely.

In long, sluggish-flow sewer lines, conditions become low in dissolved oxygen, allowing anaerobic microbes to thrive. This biological activity consumes the available oxygen and generates gases such as hydrogen sulfide, which is toxic to humans and contributes to foul odors. The gas buildup and ongoing microbial respiration can also reduce the oxygen level in the air inside the pipe and manholes. At the same time, hydrogen sulfide and other byproducts can interact with pipe materials, with sulfuric acid formed on concrete surfaces leading to biogenic corrosion of concrete and, to some extent, metal corrosion. Because all of these effects can occur together in stagnant, long sewers, all of the above conditions are likely.