MLSS-MLVSS
B.M. D’Antoni, F. Iracà, M. Romero
Panta Rei Water Solutions

Download PDF version
1. Analytical method for the determination of MLSS and MLVSS
Procedure to be followed using the instruments already present in your laboratory.
2. Determination of MLSS
- Set the temperature of the muffle at 105°C;
- Weight the blank filter and take note (Mo) [mg];
- Filter 25 ml of sample and take note of the volume (V) used [ml];
- Take the filter (after filtration) and put it in the muffle at 105°C for 2h;
- Let the dried filter for 15 min at room temperature;
- Weight the filter after dehydratation and take note (M1) [mg];
- Calculate the MLSS by the following formula.

3. Determination of MLVSS
- Set the temperature of the muffle at 550°C;
- Put the filter after dehydratation (M1) into the crucible;
- Weight the crucible+filter and take note (M2) [mg];
- Put (M2) into the muffle at 550°C for 1h;
- After 1h take out the crucible and let it cooling for 30 min at room temperature;
- Weight the crucible after incineration and take note (M3) [mg];
- Calculate the MLVSS by the following formula.

4. How to take note
Samples | MLSS (105°C - 2h) | |||
---|---|---|---|---|
Weight blank filter (MO) | Sample Volume (V) | Weight filter after dehydratation (M1) | MLSS concentration Equation 1 | |
Oxidation tank | ||||
Return sludge |
Samples | MLVSS (550°C - 1h) | ||
---|---|---|---|
Weight crucible+filter (M2) | Weight crucible after incineration (M3) | MLVSS concentration Equation 2 | |
Oxidation tank | |||
Return sludge |
If your balance weight value is in grams, multiply the results x 1000 in order to obtain mg.