Energy recovery

Biogas can be produced from wastewater with high concentrations of biodegradable carbon (BOD). Fermentation processes are stimulated by creating anaerobic conditions in a reactor designed for this purpose (CSTR, UASB or EGSB). Before the biogas produced can be used for energy generation, the following processing steps are necessary.

Biogas cooling and drying

The biogas after the anaerobic reactor is saturated with water vapour and therefore contains a large amount of moisture. To prevent corrosion processes in the further processing of the biogas, it is cooled down to 4 to 6°C in cooling plants. The resulting condensate is discharged and fed back into the inlet of the wastewater treatment plant.

Desulphurisation

The biogas produced during the fermentation process can contain other gases besides methane, which is valuable for energy. Hydrogen sulphide (H2S) is particularly problematic. In addition to its acrid odour and toxic properties even at low concentrations, hydrogen sulphide oxidation produces sulphur oxides. Sulphur oxides not only cause increased wear due to corrosion, but also act as a greenhouse gas in the atmosphere. This is why the sulphur is removed from the biogas produced. Based on the hydrogen sulphide content and the composition of the biogas, either chemical or biological desulphurisation processes are used.

Biogas storage

In order to be able to use biogas energetically and thermally, the heat- and energy-generating aggregates need a continuous supply of biogas. To make this possible, biogas storage facilities are interposed as buffers between the biogas producer and the final utiliser. These storage tanks can either be installed directly on top of the anaerobic reactor in the form of a membrane roof or decoupled from the reactor in the form of a simple biogas bag or double-membrane storage tank.

Biogas flares

Gas flares are used for the thermal oxidation of the climate-relevant methane, which is the main component of biogas, and convert it, among other things, into the less harmful greenhouse gas CO2. In the event of overproduction of biogas or maintenance work / malfunctions on individual units of the gas treatment system, flaring of biogas via the biogas flare is guaranteed at all times - to increase operational safety and to protect our environment.

Boilers / CHPs

The biogas obtained can be used for various purposes after drying and desulphurisation. It is possible to generate energy and heat in internal boilers or combined heat and power plants, or the biogas can also be fed into the public gas grid if the prescribed limits are complied with. In any case, reuse reduces running costs and protects the environment. Thanks to the various options available, we can ideally adapt our solution to the needs of our customers.