What are some operational problems that can arise during activated sludge
treatment, such as bulking, foaming, or sludge settling issues, and how can these be
addressed?
1. Bulking: Bulking occurs when the sludge settling is poor and the sludge compacts too quickly, leading to a loss of biomass from the treatment process. This can be addressed by increasing the wasting rate of sludge, ensuring proper aeration and mixing in the aeration tank, and adjusting the sludge age to optimize biomass growth and settling.
2. Foaming: Foaming can occur due to excessive growth of filamentous bacteria in the activated sludge, which can create a stable foam on the surface of the aeration tank. To address foaming, the foaming bacteria can be controlled by adding chemicals such as anti-foaming agents, optimizing aeration and mixing to prevent excessive growth of foam-forming bacteria, and increasing the wasting rate of sludge to remove excess foam-forming organisms.
3. Sludge settling issues: Sludge settling issues can lead to poor effluent quality and loss of biomass from the treatment process. To address this problem, the sludge age can be adjusted to promote the growth of settleable biomass, the wasting rate of sludge can be increased to remove excess solids, and proper aeration and mixing can be ensured to prevent sludge compaction and poor settling. Additionally, adding chemicals such as polymer flocculants can improve settling characteristics of the sludge.