Tertiary treatment

Tertiary treatment is the third stage of the wastewater treatment process, following primary and secondary treatment. This stage involves the removal of nutrients such as phosphorus and nitrogen, and virtually all remaining suspended and dissolved material in wastewater.

Overview

Tertiary treatment, also known as advanced treatment, is designed to further improve the quality of the wastewater before it is reused, recycled, or discharged to the environment. The specific processes used in tertiary treatment depend on the characteristics of the wastewater and the discharge requirements, but can include filtration, disinfection, and nutrient removal.

Filtration

Filtration is a common method used in tertiary treatment to remove remaining suspended solids from wastewater. This can be achieved through a variety of methods, including sand filtration, microfiltration, and ultrafiltration. These processes can significantly reduce the turbidity of the wastewater, improving its clarity and making it suitable for certain reuse applications.

Disinfection

Disinfection is another important component of tertiary treatment. This process is designed to kill or inactivate pathogenic microorganisms in the wastewater to ensure it is safe for discharge or reuse. Common methods of disinfection include chlorination, ultraviolet (UV) irradiation, and ozonation.

Nutrient Removal

Nutrient removal is a critical aspect of tertiary treatment, particularly in areas where wastewater is discharged into sensitive water bodies. Excess nutrients, such as nitrogen and phosphorus, can cause eutrophication, leading to harmful algal blooms and other environmental problems. Nutrient removal processes can include biological nutrient removal (BNR), chemical precipitation, and ion exchange.

Applications

Tertiary treatment is used in a variety of applications, including municipal wastewater treatment, industrial wastewater treatment, and in the treatment of stormwater runoff. The treated wastewater can be reused for irrigation, industrial processes, toilet flushing, and even indirect potable reuse.

See Also

• Primary treatment
• Secondary treatment
• Wastewater treatment plant
• Water recycling
• Water pollution