It depends upon what the rest of the biomass looks like. If the floc is small, weak, dispersed, you may have a very young sludge age. Typically the presence of flagellates, similar to amoebae indicates a high loading of food vs. the amount of biomass available to eat the organics. Flagellates possess one advantage over their amoeboid relatives in that they can swim. Therefore, enabling them to invade and adapt to a wider range of environments unsuitable for other amoebae. Usually, this means that the sludge is a bit older than if only amoebae are present and there are probably less single celled bacteria swimming around.

It may mean the sludge is young if the floc is clear, dispersed and weak, or if you have had rotifers in the past and were old, it may mean a recent high loading of BOD that is forcing the sludge age to a younger age. Usually you can expect high solids in the effluent and higher BOD levels if flagellates are present in significant numbers.

Daily microscopic analyses is helpful in documenting where you are today, where you have changed since the previous day and how to react to changes proactively as opposed to when they have become critical!

First check to see why they have increased? Is there a change in loading that might impact other areas? Check your nutrients in this case if applicable to your plant. The biggest mistake people make when a high loading comes through or a spill, especially at industrial plants is not to increase nutrient levels when high loading occurs.

You might want to adjust your wasting or RAS levels. Some plants add bioaugmentation products in cases of higher loadings. You might need to slightly increase the dosage of product. If using micronutrients, adjust these levels also if the loading is significant.

You might need to check the Bed levels in your clarifier. Check your TSS off your clarifiers.