Micronutrients or trace elements (these are mostly heavy metals) are needed in all biogas plants. The micronutrients are the central atoms in the enzymes which must be produced by the methane bacteria in order to produce biogas. Without micronutrients there is also no biogas.
A part of the needed micronutrients is mostly delivered with the substrate. If with the substrate is less delivered than needed by the biology, the process gets instable, the acids in the digester increase and the biogas yield decreases. Only at an extremely low loading rate under 1 kg/cbm/d and a very high addition of liquid manure a plant can also function well completely without an extra micronutrient addition.
By the use of micronutrients the biogas process gets more stable, considerably higher loading rates can be reached, the biogas yield is increased till the theoretical possible level and the biogas quality gets better.
Micronutrients do not make more biogas, but they enable the biology to get out everything what is possible. In contrast to an instable running plant without micronutrients the substrate need is noticeably reduced at the same performance.
The often recommended analysis of the micronutrients in the digesters delivers no meaningful data, as the micronutrients are mostly present in unsoluble compounds, for example sulphides. These cannot be „seen“ by the methane bacteria and therefore also not be used. Even if for example nickel in the analysis is sufficiently present, this does by far not mean that also sufficient nickel is bio-available for the methane bacteria. Mostly you can save the micronutrient- or trace element analysis.
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