Siloxa AG

- Activated Carbon Adsorbers



SILOXA’s FAKA range of activated carbon adsorbers for fine desulphurisation of biogas is a large filter family with 11 members in total. FAKA adsorbers are available with capacities ranging from 1500 to 7000 litres, in versions with one or two chambers, and in the TWIN FAKA version. Depending on the model, the steel adsorber containers are available with an electrostatically dissipative coating on the inside or in a stainless steel version (1.4301).

Fine desulphurisation with the FAKA type activated carbon adsorber removes hydrogen sulphide (H2S) and siloxanes from biogas, sewer gas and landfill gas etc. The removal of hydrogen sulphide is an important prerequisite for compliance with the formaldehyde limit values of TA-Luft (Technical Instructions on Air Quality Control) using a catalytic converter.

All FAKA models function in the same way. The previously dried gas is cleaned in a vertical activated carbon adsorber. The adsorbers are mounted ready for use in a steel structure. For easy changing of the activated carbon, the bottom of the container is cone-shaped (for emptying) and the top is designed so that it can be refilled with a Big Bag. When the gas is fed in, it always flows through the adsorber chamber from the bottom to the top.

The right time to change the used activated carbon can be determined from measuring points in the adsorber (e.g. with an H2S analysis or with periodical manual measurements).

In the twin-chamber versions of FAKA  – the K2 models– the separation of the chambers allows 100% usage of the carbon in the lower chamber, risk-free, as the upper chamber acts as a protective filter and prevents breakthrough of the sulphur load. This permits maximum capacity utilisation of the carbon in the lower adsorber chamber at all times, with a clear reduction in operating costs. SILOXA developed this twin-chamber process in 2003 and was the first provider to launch it on the market.


Choosing the required size always depends on the gas flow rate and the H2S load and also on the raw gas load and the changeover interval required for the activated carbon. The higher the load and the higher the flow rate, the bigger the adsorber needs to be. All the components that come into contact with gas are electrostatically conductive. The elements therefore conform to the ATEX requirements for handling biogas. The containers are designed to permanently and reliably retain their shape even at high operating temperatures (e.g. as a result of a spontaneous very high H2S load, insolation, etc.) or at high operating pressures (< 500 mbar). Some of the adsorber models have an integrated crane system with electric chain hoist for easier changing of activated carbon with Big Bags. For all filters, SILOXA offers delivery throughout Germany, as well as installation, service and proper disposal of used activated carbon.

Maintenance consists of replacing the activated carbon, followed by inertisation and function testing. For this we can offer full service and delivery service.

Full service is performed by our skilled service technicians. It comprises delivery of activated carbon, discharge of the saturated activated carbon and filling with fresh activated carbon, inertisation and function testing. And of course, SILOXA takes care of the proper disposal of the saturated carbon.

The delivery service comprises delivery of the activated carbon by Siloxa, and is suited to operators who wish to replace the activated carbon themselves. Here too, SILOXA takes care of the proper disposal of the saturated carbon.

Our customers have the choice of two different types of activated carbon. For adsorption of hydrogen sulphide (H2S) and siloxanes, we recommend a water vapour activated doped moulded activated carbon. dopetac sulfo 100® is an activated carbon made from charcoal and has the highest uptake capacity on the market. DGF-4 activated carbon is only intended for adsorption of siloxanes. It is produced from coal by water vapour activation. Further information can be found in the Activated Carbon area.

Maintenance is carried out in accordance with VDMA (German Engineering Association) standard sheet 24186 part 3. There must be an 80 - 100 cm clear area around the plant allowing free access for maintenance. The biogas plant can and must be kept in operation during maintenance. Brief interruptions or a reduction in the flow rate must be agreed with the operator.

Gas heating system and filters
General visual inspection to check for damage and corrosion on the flange connections, butterfly valves and temperature displays. The flange connections are also checked for leaks.

Control unit
Inspection of the control unit is based on VDMA (German Engineering Association) standard sheet 24186 part 4. Checking for wear and improper handling of the control component, sensors and regulators.

Detailed maintenance instructions are provided in the documentation relating to the supplied plant. The maintenance performed is documented in the maintenance book. This demonstrates that maintenance has been carried out correctly and professionally, which ensures the validity of the warranty.

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