Tennessee Wastewater Operator Practice Exam

Which valuable nutrient can be recovered from anaerobic digesters?

1. Nitrogen

2. Phosphorus

3. Potassium

4. Calcium

The correct answer is: Phosphorus

Anaerobic digesters are systems that treat wastewater and organic waste by breaking them down in the absence of oxygen. The process generates biogas, primarily composed of methane and carbon dioxide, while also producing digestate, a residual material that contains valuable nutrients. Among these nutrients, phosphorus is one of the key recoverable elements. Phosphorus is essential for various biological processes, including energy transfer and the synthesis of DNA and RNA, making it a crucial component in fertilizers and agricultural applications. The recovery of phosphorus from anaerobic digesters is particularly significant because it helps to close the nutrient loop by recycling this critical nutrient back into the environment for agricultural use. While nitrogen, potassium, and calcium also play vital roles in plant nutrition, anaerobic digesters are specifically notable for their ability to efficiently recover phosphorus, contributing to sustainable nutrient management practices. This makes the recovery of phosphorus from anaerobic digesters a valuable aspect of wastewater treatment and resource recovery.