A more thorough explanation:

EFFLUENT

Effluent is liquid waste that is released into a river, lake, or other body of water.

• A factory that produces chemicals may release effluent into a nearby river.
• A sewage treatment plant discharges effluent into the ocean.

These examples illustrate how effluent is liquid waste that is released into a body of water. The first example shows how a factory may release chemicals into a river, which can harm the environment and wildlife. The second example shows how sewage treatment plants release treated wastewater into the ocean, which can affect the water quality and marine life.