How often do you perform microscopic exam of your wastewater?

Free swimming and crawling ciliates common in healthy wastewater systems

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Microscopic exam should be performed daily or every shift by operators. When I say microscopic exam, I am not referring to filamentous bacteria ID or using any stain procedure. Instead, use a decent quality microscope (can be phase contrast or more simple light microscope) and have the operator look at a sample at 100x and 400x magnification (10x & 40x objectives). Use a standard transfer pipette to place a small amount of fresh MLSS on a slide. If you have a lagoon system, you will need to use a centrifuge to collect sufficient biomass to observe. Here is what should be noted - I promise it takes less than 30 seconds:

• Note floc size, density, and filaments - compare to "normal" system levels (100x)
• Free bacteria and pin floc (best seen at 400x)
• Now look for indicator protozoa (amoeba, flagellates, ciliates, and stalk ciliates)
• Any higher life forms such as rotifers or worms
• Finally, anything unusual or big changes from previous exam

A good idea is to use a written exam sheet with indicator organisms and floc characteristics recorded. This can be used to establish baseline observations and detect when something is impacting a system's biomass. Early detection of shocks, bulking, and F/M changes can be seen using microscopic exam before changes happen in SV30, foaming, or effluent quality.