The preparation of the substrate consists in obtaining the physical-chemical characteristics considered optimal for introduction into the digester.
This occurs through the introduction of the matrices, possibly diluted by sludge and / or water, with a correct degree of humidity inside the EMPOWERING DEVICE which will homogenise all the matrices entered and pre-treat the result obtained, also contributing to the increase of the its temperature.
The permanence time of the matrix inside the biodigestor, normally 14/40 days (mesophilic reactors) or 14/26 days (thermophilic reactors), thanks to the pretreatment in the EMPOWERING DEVICE this permanence can be reduced to about one day and therefore reactors can be of extremely smaller dimensions than in the past can be made.
These are fed and, alternatively, emptied in cycles of 6 hours. They are equipped with biogas collection systems. During the pemanence, the material is continuously stirred through an innovative helical device that is moved only by exploiting the rise of the gas from the bottom to the top, without consuming additional electricity. This allows to avoid the presence of dead zones, to homogenize the temperature and the release of the biogas and to avoid the sedimentation of the mud and the formation of superficial films and above all it facilitates the contact between bacteria and substrate.
The biogas obtained can be either upgraded to biomethane or, once purified, used for the low yield production of thermal or electric energy. It is a gaseous mixture composed mainly of methane and carbon dioxide, but also containing small quantities of hydrogen and occasionally traces of hydrogen sulphide.
The material exiting the digester is a liquid sludge (Solid Fraction: 5-25%) not completely stabilized (the organic matter is not completely degraded). It is stabilized through a second passage in the EMPOWERING DEVICE, which remove its bacterial load and accelerates its oxidation; subsequently, excess moisture is drained by means of a belt press. Any excess nitrogen can be eliminated chemically, via bacteria or naturally with the compost rest.
The liquid fraction thus obtained, having already undergone treatment within the EMPOWERING DEVICE, can be used immediately for irrigation purposes or to be returned to the cycle by finding new use in the biodigestor. The dry fraction is used as a biological fertilizer (high quality compost). The electricity produced by anaerobic digestion is considered totaly green energy because the gas is not released directly into the atmosphere and carbon dioxide derives from an organic source characterized by a short carbon cycle, the biogas with its combustion does not contribute to the increase of atmospheric CO2 concentrations and, therefore, is considered a low environmental impact energy source.
