What is the ideal ratio of Carbon, Nitrogen, and Phosphorus for the activated sludge process?

The ideal ratio of Carbon, Nitrogen, and Phosphorus for the activated sludge process is often presented as a ratio that supports optimal microbial growth and effective wastewater treatment. The correct answer represents the typical stoichiometric ratios that microorganisms use in the biological treatment of wastewater.

In this case, a ratio of 100 Carbon to 10 Nitrogen to 1 Phosphorus (100C:10N:1P) closely matches the requirements for the microbial populations responsible for breaking down organic matter in wastewater. This ratio indicates ample availability of carbon as an energy source, which is essential for the growth and metabolic activities of bacteria. The nitrogen serves as a key building block for nucleic acids and proteins, while phosphorus is critical for energy transfer (as ATP), nucleic acids, and cellular processes.

In a well-balanced activated sludge system, maintaining these ratios is crucial to ensure that the microbial community can efficiently treat the wastewater, minimizing the risk of nutrient limitation or excess that could lead to suboptimal treatment performance.