Microscopic examination of mixed liquor can be a significant aid in the evaluation of the activated sludge process. The presence of various microorganisms within the sludge floc can rapidly indicate good or poor treatment. One of the operator’s primary jobs is to provide a favorable environment to support bug life. Knowing when and how to use a microscope is one of the most important tools in an operator’s toolbox to help provide this favorable environment.
Looking around your wastewater lab, you may have noticed an old grade school quality microscope gathering dust in a forgotten corner. While this piece of equipment may not be a Cadillac, it can certainly be useful in observing basic mixed liquor characteristics. More sophisticated microscopes can show greater detail, but the important thing to remember is to use this tool to your benefit and not be intimidated. The cost of a good microscope is around 2,000 to 3,000 dollars. The grade school microscope in the corner of the room is a good start until you can upgrade to a phase contrast microscope for improved viewing clarity. Optional equipment such as a camera is also useful but not a necessity.
The question is, when and how do I use this tool?
For the most part, the answer is: regularly while the system is running properly. Looking at changes in the biology can reveal process problems before they are detected in effluent quality. These biological changes can be anything from poor floc formation, the appearance of various filaments, or the loss of higher life forms. These changes can indicate various conditions from long sludge age and low D.O. to high levels of FOG and potentially toxic substances in the influent.
Being a visual tool, the microscope can help the operator give life to many of the abstract tests and calculations necessary for plant operation. Regular observations can reveal characteristics of system health, sludge age, changes in operational pressures, nutrient removal efficiency, influent loading, and is useful in remediation of filamentous organisms. Nothing grabs your interest like looking at your bugs on their level, and how they are thriving within your plant. The microscope helps to put the operator in the bugs’ world.
General usage for process control involves observing several key features.
- Floc Characteristics
- Filament Quantity and Type
- Higher Life Forms
- Bulk Water Characteristics
These basic characteristics can provide a snapshot of both the general and specific health of activated sludge. This can greatly aid the operator’s decision-making process when addressing system process control issues on both a daily basis and when serious problems arise.
The microscope can be extremely valuable when unexplained problems occur. For example, earlier this year one of our clients in north Georgia was experiencing an unknown issue with loss of nitrification and BOD removal. Their initial investigation showed that environmental conditions were good and influent quality appeared to be normal. However, observation of the system under the microscope revealed that their system was infected with yeast which was robbing activated sludge bacteria of available D.O. The yeast was found to have originated from a hauled waste stream accepted from an industrial bakery. This issue would not have been discovered by any other method than the microscope!
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