If your measured F:M ratio is too LOW, what action should you take?

When the measured Food to Microorganism (F:M) ratio is too low, it indicates that there are not enough nutrients (food) available to support the biological treatment processes effectively. A low F:M ratio means that the microorganisms in the system are not adequately fed, which can lead to poor performance in the treatment of wastewater.

Increasing the waste rate allows for more influent (untreated wastewater) to enter the biological treatment system, providing additional food sources for the microorganisms. This step is crucial because it raises the overall concentration of organic matter (BOD) in the system, thereby providing more nutrients for the microbial population to thrive and perform optimally.

In contrast, decreasing the waste rate or reducing the influent BOD would further limit the food available for the microorganisms, exacerbating the problem of a low F:M ratio. Increasing aeration time may not directly address the issue of food shortage, as it focuses more on ensuring the oxygen supply for the microorganisms rather than enhancing their nutrient availability. Therefore, increasing the waste rate is the most effective corrective action to take when faced with a low F:M ratio.