Ways to Reduce Wastewater Foam in Treatment Plants [GUIDE]

Wastewater Foam

Wastewater foam is a common occurrence in treatment plants. But too much foam could be a symptom of a larger problem. In this guide, we look at what wastewater foam is and how to reduce it in your treatment plant.

In a wastewater treatment plant, foam is a sticky, brown mass of bubbles that forms on the top layer of water. While it’s common for a treatment plant to have some wastewater foam, the problem occurs when there is so much foam that it hinders the plant’s operations.

What Causes Wastewater Foam?

There are three main causes of excessive foam:

  • Excessive amounts of surfactants in the wastewater can generate foam.
  • A young sludge produces white, fluffy foam in the aeration basin of the treatment plant.
  • Excessive amounts of fats, oil and grease (FOG) or some other chemicals can cause the growth of foam-forming filamentous bacteria.

Wastewater foam is an indicator of how well a plant is performing. When you see too much foam, it’s a sign the plant has issues that need fixing.

Why Is Wastewater Foam a Problem?

1. Maintenance

When there is too much wastewater foam in an aeration tank, it can overflow and get all over the equipment, railings, floor, and other areas. In extreme cases, the foam may damage electrical equipment and/or create safety issues by making walkways slippery. Cleaning up the mess takes time and money that you could be spending on more important tasks.

2. Operations

From an operations standpoint, wastewater foam can be a nightmare. Foam that’s generated from filaments, such as Microthrix Parvicella or Nocardioforms, is the result of a growth substrate pressure that produces too many filamentous organisms in your system.

And foam can sometimes carry biosolids or undigested surfactant into the clarifier or effluent, which then travels out of the treatment plant, causing you to fail your permits.

So, how can you get rid of foam before it becomes detrimental to your wastewater treatment plant? Let’s look at four possible answers.

How to Reduce Wastewater Foam: 4 Solutions

Since every wastewater treatment plant is different, there’s no one-size-fits-all approach to reducing foam. That said, there are four main solutions that have been proven to work time and again: spray the foam, physically remove the foam, add chemicals or bioaugmentation.

1. Spray the Foam

Many wastewater treatment plants try to knock down the foam by spraying it with water from a hose, much like how firefighters spray water to douse a fire. While this may keep the foam from flowing out of the tank, it won’t fix the underlying cause of the foam in the first place.

2. Physically Remove the Foam

Another solution is to physically remove the foam by skimming it off the top using a vacuum truck – a specialized truck that uses a pump and hose to suction the foam into an attached tank. Vacuum trucks are typically used in emergency situations when you need to minimize the foam immediately and find a more permanent resolution later.

3. Add Chemicals

Chemicals, like anti-foaming agents, are liquids that you inject or dose into the water to help prevent foam from occurring. This is an accepted method of foam control, however, it does not address the root cause.

4. Bioaugmentation

If you want to get to the bottom of your foam problem – and more effectively control it – consider applying specifically formulated microbes to the wastewater. If you choose to go this route, partner with a bioaugmentation expert – someone who specializes in adding microbes to biomass to remove the foam-causing constituents before they can be expressed as foam.  This provides for a more stable system capable of producing an acceptable effluent.

A bioaugmentation expert can help:

  • Examine your wastewater treatment plant to learn more about the foam problem.
  • Take samples of both the foam and the biomass for lab testing.
  • Offer specific solutions based on the lab results.

There is a range of available bioaugmentation products that reduce foam (see a detailed list at the bottom of this page). An expert will be able to recommend the exact solution for your needs.


While it’s normal to have some wastewater foam in your treatment plant, having too much of it is a problem. Luckily, there are solutions available to reduce foam that are both quick and cost-effective. Since treatment plants differ, it’s a good idea to work with a bioaugmentation expert who can get to the root of your foam problem and offer a permanent solution.

Monera Technologies provides high-end consulting, comprehensive lab services and cost-effective bioaugmentation solutions for wastewater treatment plants. Contact us to learn how we can bring a holistic approach to your facility’s foam problems.

Examples: How Bioaugmentation Products Are Used to Fight Foam


MICROCAT-DF is a biocompatible liquid defoamer that you dose into the wastewater to reduce the foam with a chemical reaction. It’s formulated for aeration tanks and sludge digesters to reduce foam without inhibiting the biomass or causing other negative side effects typically associated with conventional defoamers.

In one scenario, a food processing wastewater sequencing batch reactor (SBR) treatment unit struggled with foam control. Within two days of using MICROCAT-DF, the treatment plan saw a significant reduction of foam. The solution was both quick and cost-effective.


MICROCATXF is a filament control blend formulated to reduce filamentous microbe populations, improve sludge settling and reduce effluent suspended solids.

Once you get your wastewater foam to a preferable level, you can also use MICROCAT‑XF for preventive maintenance purposes, which helps to enhance overall system performance while reducing operating costs.

For example, a municipal wastewater treatment plant used MICROCAT-XF for filamentous growth reduction. Unfortunately, toxic shock and cold weather allowed filaments to take over the treatment system and nearly wipe out the typical biomass. Thanks to MICROCAT-XF, the plant brought higher life forms back in greater numbers and eliminated the presence of filaments.


MICROCAT-DNTRF is a synergistic blend of preselected, adapted microorganisms for liquefying and degrading FOG. In addition, it helps to maintain plumbing systems and keep collection systems free of blockages.

When a microbial filamentous infestation caused excessive foaming that interfered with a municipal treatment plant’s operations, MICROCAT-DNTRF came to the rescue.

Thanks to its FOG degrading bioformula, MICROCAT-DNTRF managed to:

  • Quickly reduce the foam and filaments
  • Reestablish a healthy biomass
  • Increase clarifier settling rates
  • Reduce effluent total suspended solids (TSS)
  • Reduce effluence biochemical oxygen demand (BOD)