What is the ideal BOD, nitrogen, and phosphorus ratio for microorganisms to grow in activated sludge systems?

The ideal ratio of BOD (Biochemical Oxygen Demand), nitrogen, and phosphorus in activated sludge systems is crucial for optimizing the growth of microorganisms responsible for breaking down organic matter effectively. The correct ratio of 100:5:1 means that for every 100 parts of BOD, there should be 5 parts of nitrogen and 1 part of phosphorus.

This specific proportion ensures that microorganisms have sufficient nitrogen and phosphorus as essential nutrients for growth, reproduction, and metabolic processes, which are vital for effective processing of wastewater. Nitrogen is a key component of amino acids, proteins, and nucleic acids, while phosphorus is critical for energy transfer and cellular function, primarily through ATP (adenosine triphosphate).

When the nitrogen and phosphorus levels are balanced with BOD in this manner, the microbial community can thrive, leading to efficient degradation of organic pollutants, improved treatment performance, and reduced risk of nutrient limitation that could hinder biological activity.

Other ratios may indicate imbalances where either nitrogen or phosphorus may be too low or too high, potentially leading to suboptimal microbial growth or the risk of environmental issues, such as nutrient pollution in receiving waters. Thus, the 100:5:1 ratio is recognized as optimal for nurturing a