Slide Preparation and Staining

Wet Mount

1. A drop of activated sludge is placed on a clean grease-free glass slide.
2. A clean cover-glass is placed on the drop.
3. Avoid entrapment of air bubbles as much as possible.
4. The size of the drop should not be so large that the cover-glass floats and it should not be so small that it doesn't fill the entire space under the cover-glass.
5. Use a pipette with a small opening.

Fixed Smears and Staining

1. Place a drop of activated sludge on a clean, wax-free slide and smear.
2. Let the slide air dry. Do not heat fix!

Mixed Liquor Sample Collection

The sample should be collected from the discharge end of the aeration basin. Slides should be made from a fresh sample of mixed liquor. If the sample has been collected and can not be examined right away, the sample should be aerated until it can be evaluated.

Return to Activated Sludge: Microbiology and Process Control.

Additional technical assistance with wastewater treatment plant operations is available from the DNR. Contact Jack Saltes in Madison at (608) 264-6045. For additional help from the DNR, you might also try the Laboratory Certification Program.