If you encounter dark foam, high MLSS, and slow settling sludge, what is the best course of action?

The situation described involves dark foam, high Mixed Liquor Suspended Solids (MLSS), and slow settling sludge, which are indicative of potential issues in the activated sludge process. The best course of action is to maintain a sludge blanket of 1-3 feet, closely monitor the MLSS, and increase the Dissolved Oxygen (DO) levels if necessary.

Maintaining a sludge blanket within this range is crucial for ensuring that there is adequate biomass to facilitate the treatment of wastewater while also preventing excessive solids in the system. A well-managed sludge blanket helps in the effective settling of solids and prevents issues such as scouring or washout of microorganisms, which can lead to operational problems and reduced treatment efficiency.

Monitoring the MLSS is an important aspect because it allows operators to gauge the concentration of microorganisms in the system. High MLSS can indicate a potential bulking issue or poor settleability, and making adjustments is essential in ensuring that the treatment process remains effective.

Increasing the DO can be critical in situations where there is a risk of anaerobic conditions developing, which can contribute to dark foam formation and poor sludge characteristics. By ensuring that there is sufficient oxygen in the system, the health of the microbial population is maintained, supporting better settling and reducing fo