A complete mix activated sludge plant has a fast settling sludge and high amounts of pin floc leaving the clarifier. What is one method of correcting this problem?

In a complete mix activated sludge plant experiencing fast settling sludge and high amounts of pin floc leaving the clarifier, one effective method to address this issue is by increasing the food-to-microorganism (F/M) ratio by wasting more mixed liquor. This approach can enhance the growth and activity of microorganisms in the reactor.

When the F/M ratio is increased, it means that there is more substrate available for the microorganisms, which can promote better floc formation and cohesion among the biomass. A higher concentration of food encourages the organisms to grow and form larger flocs, which typically settle better in the clarifier.

This method aims to balance the microbial population and improve sludge characteristics, thereby reducing the amount of pin floc that escapes to the effluent. It is essential to manage this correctly, as too high an F/M ratio can lead to other issues, but it is a practical solution in the given scenario to mitigate the problems of fast settling sludge and excessive pin floc.