Understanding Different Types of Wastewater Treatment

9 August 2023
 Categories: , Blog


Wastewater treatment is a critical process that safeguards the environment and public health. It involves the removal of contaminants from wastewater that can be returned safely to the water cycle. This blog post will explore different types of wastewater treatment methods.

Primary Treatment

The first stage in most wastewater treatment processes is the primary treatment. This involves the physical removal of large solids from the wastewater through screening and sedimentation. Screenings catch large debris like rags, plastic, and other solid objects. The remaining water then goes into a sedimentation tank where gravity helps settle the suspended solids, forming a layer of 'sludge' at the bottom of the tank. The clarified water then proceeds to the secondary treatment.

Secondary Treatment

Secondary treatment takes care of the dissolved organic matter that escapes primary treatment. This stage uses biological processes to further purify wastewater. One common method is activated sludge, which introduces microorganisms into the wastewater. These organisms consume organic waste material, converting it into water, carbon dioxide, and energy for their growth and reproduction.

Here's where aeration plays a pivotal role.

Aeration is the process of adding air into wastewater, allowing the aerobic biodegradation of pollutants. It provides oxygen to the bacteria so they can metabolize the organic material, breaking it down further. This process not only helps reduce pollutants in the water but also aids in mixing to disperse the air and keep the microbes in suspension.

There are two main types of aeration methods used in wastewater treatment:

  • Surface Aeration: In this method, air is introduced at the surface of the wastewater. Equipment like paddle wheels or fountains will churn the water to mix in the air.
  • Subsurface Aeration: Here, air is introduced below the water surface. This can be accomplished via diffusers or aerators that create bubbles to provide oxygen to the bacteria.

Tertiary Treatment

Tertiary treatment, also known as advanced treatment, is designed to further improve the quality of the effluent after secondary treatment. This stage can remove almost all impurities from wastewater, making the treated water safe enough to be released into sensitive ecosystems.

Tertiary treatment techniques include filtration, lagooning, nutrient removal (such as nitrogen and phosphorus), and disinfection methods like chlorination or ultraviolet (UV) treatment.

From primary to tertiary stages, each step in the wastewater treatment process has a crucial role in protecting the environment and ensuring water is safe before it's returned to the water cycle. Among these processes, aeration remains a key player in the effective treatment of wastewater. By understanding these different methods, anyone can appreciate the complex science behind wastewater treatment and its significance in the world.

Contact a local company to learn more about wastewater aeration systems.