Which of the following can be decomposed in an aerated tank?

Organic matter

The correct answer is option 1. Organic matter.

Out of the options listed, only organic matter can be decomposed in an aerated tank.

Here's why:

Aerated tanks are used in the biological treatment stage of wastewater treatment. They are designed to provide oxygen to aerobic bacteria, which are microorganisms that require oxygen to break down organic matter.

Organic matter consists of carbon-based compounds derived from living organisms, such as food waste, human waste, and decaying plant matter.

Aerobic bacteria can decompose organic matter into simpler compounds like water, carbon dioxide, and inorganic nutrients.

Inorganic matter, on the other hand, is non-living and cannot be readily broken down by bacteria. Examples of inorganic matter include sand, gravel, and minerals. These materials are typically removed from wastewater through physical processes like sedimentation and filtration before it reaches the aerated tank.

Therefore, while both organic and inorganic matter may be present in wastewater, only organic matter can be decomposed by the aerobic bacteria in an aerated tank.