Which statement is false? chlorine, ozone and uv light can be used to disinfect water. methane is a by-product of anaerobic digestion. trickling filter systems are used for secondary water treatment. removal of nitrates by microorganisms requires aerobic conditions. artificial wetlands provide a habitat for wildlife.

Option (4).

Explanation:

Denitrification may be defined as the removal of the nitrates from the environment with the help of microorganism. Denitrification is important for the maintenance of nitrogen in the environment.

Aerobic conditions refers to the conditions that has free supply of oxygen where as anaerobic condition has limited supply of oxygen. The anaerobic bacteria are living in the anaerobic condition and perform denitrification in absence of oxygen.

Thus, the answer is option (4).