Defoamer and defoamer metering technolgy

Causes of foaming in biogas plants

The occurrence of foam is one of the most common disturbances of anaerobic degradation of organic substrates in biogas plants. Foam is often an indicator of the presence of suboptimal operating conditions of the biogas plant. For the formation of foam, various factors come into account. Very frequently, foaming problems are observed when high-protein substrates, such as grains or dry manure of poultry, are fermented. The hydrophobic lipids formed during degradation of these substances separate at the liquid surface which contributes to stabilizing the foam bubbles. Another cause of foaming is excessive feeding with easily degradable substrates. This causes a temporary imbalance between acid formation and further conversion to methane. As a result of this additional microbial stress, foaming is commonly observed.

Pb Antischaum und Entschäumerdosiertechnik

Effects of occurrence of foam

The presence of foam in a biogas plant represents a serious technological problem that can result in considerable economic disadvantages. Examples of the consequences of foam include:

  • Obstruction of gas discharge by forming a floating layer
  • Fouling or blockage of gas lines
  • Fouling of the fermenter and the entire biogas plant by effervescence
  • Reduction of fermentation time by incomplete utilization of the digester volume
  • Interference in process control by impairment of measuring probes


One possibility for short-term control of foam problems in a biogas plant is the use of anti-foaming agents. These products reduce the surface tension of the fermentation medium and in this way effectively work against the occurrence of foam bubbles. For a uniform addition of anti-foaming agent, adjustable diaphragm metering pumps have proven particularly suitable. HeGo Biotec GmbH offers different defoamers and a variety of metering pumps for extracting the defoamer directly from the packaging, as well as complete metering stations.

Defoamer of the Antischaum series

Defoamers of the Antischaum 20xx series are highly concentrated and highly efficient liquid products. HeGo Biotec GmbH offers Antischaum products that contain no silicone compounds or mineral oils. They are also biodegradable. These products have a very good effect both in spontaneous defoaming and in foam prophylaxis. From the extensive range of Antischaum products, Antischaum 2050 has proven particularly suitable for biogas plants. The application of this product is defoaming of different liquid media, such as fermenter contents, liquid substrates (manure), the percolate liquid of dry fermentation plants, and the filtrate from the dewatering of fermentation residue.

Defoamer metering technolgy

A uniform addition to the liquid substance is crucial for high effectiveness and efficiency when using defoamers. For this task, diaphragm metering pumps have proven particularly suitable. The addition of defoamers should take place directly onto the medium to be defoamed at a turbulent location to ensure thorough mixing. With the metering pump PKX MA-A, HeGo Biotec GmbH offers a particularly low-cost solution. The metering pump, IWAKI EWN-B11, in contrast, has added features such as frequency and stroke length adjustments, LCD display, external control, an input for an “empty” signal. Standardly, the metering pumps are offered with a suction unit for direct removal of the defoamer from the packaging and a metering valve with backflow prevention. Both pumps are also available as part of a completely assembled metering Station.