In activated sludge wastewater treatment one of the most commonly run and important tests is the settleometer or sludge settling test. While there are special 2L plastic cylinders made for this test, most facilities use a 1L graduated cylinder for settling tests. No matter which cylinder you use, make sure you use the same cylinder to ensure consistency and useful results.
Add 1000 ml of mixed liquor to the cylinder. Start timer an allow the product to settle. You can take readings every 5 minutes, but often we just take a reading after 30 minutes. By tanking readings every 5 minutes, you get a settling curve that provides more information on how the floc performs in secondary clarification. While we normally use the SV30 number, in systems with changing MLSS concentration or comparing different systems, we would do the SVI calculation. SVI > 150 is con
SVI = SV30/ MLSS (in grams)
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
Click to set custom HTML