Pin-floc
Pin-floc is a tiny, dark, pinpoint-sized floc found in very old sludge. Pin-floc is associated with three distinct problems.
- Pin-floc is often experienced when the treatment plant is under loaded and the suspended liquor solids of the mixed liquor cannot be further reduced than the current value. When it is reduced, the concentration becomes so low that effective settling becomes impossible. Normally, one would try to lower the MCRT, but this would need waste and a lower MLSS, which rarely works in this situation. It could be useful to try growing certain filaments that slow settling and promote solid capture, such as low DO filaments. Maintaining a DO in the aeration tank between 0.1 and 0.5 usually allows low DO filaments to grow. Take care!
- Pin-floc is also linked to clarifier denitrification. Bacteria degrade nitrate to nitrogen gas, and the resulting bubbles lift floc particles to the surface. Ashing or clumping is a common occurrence. By reducing the total sludge units in the system, a treatment pressure is required. A slight increase in wasting usually solves the problem, but higher returns may also be required. If a higher return rate is used, ensure that the other process demands, such as SDT A, are met. Return rates that are far too high are all too common. On/off aeration or an anoxic zone in the aeration tank may also be beneficial. It allows denitrification to occur in the aeration tank, where it is not an issue, instead of the clarifier, where it is.
- Pin-floc can also occur in systems where solids are returned unintentionally from solids processing. Excessive loads of pin-floc sludge particles can be caused by excessive solids in anaerobic or aerobic digester supernatant, as well as inappropriate solids capture from sludge dewatering systems. They may or may not be related to denitrification, so it is important to determine which is causing the problem.
No comments:
Post a Comment
If you have any doubts, Please let me know