Here is an overview of how a test is performed:

• Review the operation manual for the centrifuge you've purchased.      Always wear necessary PPE when sampling and during centrifuge operation. Sample from the aeration basin during normal operation. 
• Retrieve a sample for the permitted, lab-based analysis to get a true value of the Mixed Liquor Suspended Solids in the Bioreactor tank.      This value will come back in mg/L.
• At the same time you're sampling for the lab based analysis, take a sample to perform the centrifuge test, referencing the O&M manual.  Record this value.      Take pictures to document if you'd like.
• Once you have received the MLSS value back from the lab, you can determine the multiplier to use for future centrifuge tests.  Perform the lab tests every few months to verify your MLSS multiplier and ensure permitting compliance.

Here’s an example:

1. Lab test comes back with a MLSS of 5,000 mg/L.
2. Centrifuge test is done and the vial reads a “4.” 
3. Take the value from the lab result, 5,000 mg/L and then divide the 5,000 by 4 to get 1,250.  This is your multiplier to use for future centrifuge tests. 

Example: A few days later, you draw a sample and run a centrifuge test.  The vial reads 4.5.  Multiply that by your multiplier value of 1,250 and the value you get is 5625 mg/L, record as the MLSS for that day. Make sure to verify your results against lab analysis every few months.