Question

Which of the following steps is required after biological processes have broken down organic material in wastewater?

1) Water is placed in an aeration basin to increase oxygen.
2) Primary clarifiers separate solids from greases, fats, and oils.
3) Grit screening removes rocks and objects from the water.
4) Disinfection purifies water before it is released.

Answer 1

The required step after the biological breakdown of organic material in wastewater is disinfection, designed to purify water before its release.

Step-by-step explanation:

After biological processes have broken down organic material in wastewater, the next required step is disinfection. This is crucial because it purifies water before it is released back into the environment. Disinfection can be achieved through various methods such as treatment with chlorine, ozone, ultraviolet light, or bleach. These processes are designed to kill most microbes, ensuring that the water is safe for discharge to surface waters or reuse for other purposes like irrigation or habitat preservation.

Other steps mentioned, like placing water in an aeration basin (step 1), using primary clarifiers (step 2), and grit screening (step 3), are all essential stages of wastewater treatment but typically occur before the biological breakdown of organic matter.