What is Eutrophication?

Eutrophication in wastewater treatment refers to a process where water bodies receive excessive nutrients, leading to the overgrowth of algae and other aquatic plants.

The process of eutrophication starts when excess nutrients, primarily nitrogen and phosphorus, are introduced into a water body—such as rivers, lakes, or oceans. These nutrients fuel the rapid growth of algae and aquatic plants, resulting in an algal bloom.

Algal blooms can drastically reduce water clarity and quality, and are often the first visible sign of eutrophication.

The core issue with eutrophication is oxygen depletion. As the blooming algae and plants die, their decomposition consumes large amounts of dissolved oxygen, creating anoxic conditions that threaten aquatic life.

Fish and other organisms may struggle to survive or be forced to leave their habitats, disrupting the entire ecosystem. Some algae also produce toxins that are harmful to both aquatic species and humans, increasing the risk to water safety and public health.

How Wastewater Treatment Plants Help Prevent Eutrophication

To combat eutrophication, wastewater treatment plants use biological nutrient removal (BNR) processes. These advanced methods combine biological and chemical treatments to convert excess nitrogen and phosphorus into forms that can be removed from the effluent.

The goal is to discharge treated water with minimal nutrient levels—reducing the risk of triggering eutrophication in downstream ecosystems.