Water Treatment Plant Operator how-to
How to Perform a 30-Minute Settleability Test
The settleability test helps wastewater operators gauge how well activated sludge will settle in clarifiers.
The settleability test helps wastewater operators gauge how well activated sludge will settle in clarifiers. In short: collect; gently; start, then complete the remaining steps below.
Step by step
Collect a representative sample of mixed liquor from the aeration basin.
Gently mix and pour it into a settleometer up to the 1,000 mL mark.
Start a timer immediately.
Record the settled sludge volume at regular intervals, especially at 30 minutes.
Observe the sludge color, clarity of the supernatant and any floating solids.
Calculate the sludge volume index if you have the mixed liquor suspended solids value.
Use results with other data to adjust wasting and process control.
Safety reminders for water treatment plant operators
- Wear PPE and use proper procedures when handling chlorine and other chemicals
- Follow confined-space entry procedures for tanks, vaults and wet wells
- Lock out pumps and equipment before maintenance
- Stay current on vaccinations and hygiene when working with wastewater
Key terms
Coagulation · Flocculation · Sedimentation · Filtration · Disinfection · Chlorine residual: see the full water treatment plant operator glossary.