What is causing foaming, filaments and BOD violations in your wastewater treatment plant? Knowing your 30 minute settling may tell. The cause of different types of settling will vary and understanding  settling will give you more insight on the issues occurring in your plant. A 30 minute settling test will point you in the right direction to diagnose these issues.

When your solids are not settling, this is due to filaments and dead bacteria. Your best option is to use our VitaStim Low F:M. Designed for low food to microorganism conditions, VitaStim Low F:M will allow for a robust biomass of flock-forming bacteria to form and prevent filamentous bulking and cloudy effluent by introducing biostimulants and micronutrients. Aquafix often prescribes this as a buffer for many situations including septicity, restarting tank/plant, and poor settling. For best result combine with Foam Buster.

The diagram below will give you an idea on better understanding your settling and point you in the right direction of a obtaining a clear effluent.


Poor Settling

  • Settling greater than 700 ml, plant is in jeapardy of violating TSS and BOD limits
  • Bacteria may be dead
  • Mixed liquor may look spongy or elastic in nature
  • Operators will need to use combinations of Accelerator 7, Qwik-Zyme L, VitaStim Grease, and VitaStim Low F:M. Call for best treatment

Like A Rock

  • It “settles like a rock”: settles very fast and leaves a cloudy effluent
  • Settling less than 200 ml can mean bacteria are sick, dead, or hit with toxicity
  • Life under the microscope is limited
  • Evidence of shelled ameobas is a sign of toxicity
  • Use VitaStim Low F:M to rebalance

Good Settling

  • Settling between 200-500 ml is fairly good
  • The effluent should be clear and no foaming will be present
  • Mised liquor should look like dry flakes settled at the bottom

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