What action should be taken to correct a problem when high F:M ratio is indicated in an aeration tank?

In wastewater treatment, a high food-to-microorganism (F:M) ratio in an aeration tank indicates that there is too much organic material available for the microorganisms relative to the mass of the microorganisms themselves. This condition can lead to several problems, such as the potential for poor treatment performance, low effluent quality, and the inefficient usage of the microorganisms if they are not properly managed.

To correct a high F:M ratio, decreasing the wasting of excess sludge is the most effective action. By reducing the amount of biomass removed from the system, the concentration of microorganisms in the aeration tank will increase. This helps to balance the ratio, allowing for better degradation of the organic matter present in the wastewater. The optimal F:M ratio ensures that the microorganisms can effectively process the organic material without being overwhelmed, thereby enhancing the treatment process.

Other actions, such as increasing the oxygen supply, may support higher microorganism activity but do not directly address the imbalance indicated by a high F:M ratio. Similarly, increasing sludge retention time can have benefits, but without addressing the excess food available to the microorganisms, it may not solve the immediate problem of the high F:M ratio. Reducing aeration time could potentially decrease the oxygen available, which may not be appropriate