Fritsch Milling and Sizing

Processing silage for biogas

Source: Fritsch Milling and Sizing

Loppings of diverse origin are increasingly used for the production of biogas. Thereby is the construction of biogas plants and their optimisation in regards to science still a broad field of activity.
The task consisted of processing fresh silage, as well as corn and grass silage in the same manner. Goal of the work is the determination of the chemical oxygen demand the CSB value.
For this purpose various suppliers offer ready made testing solutions, for example CSB according to Dr. Lange or by Riedel-de Haen the vessel test 37737 „AQUANAL“. Hereby, the mass of oxygen per volume unit which reacts in standardised conditions with the in water suspensions contained oxidisable substances, is measured as a potassium dichromate equivalent in a sulphuric solution via photometry. The CSB value correlates with the results of the fermentation tests of organic substances performed according the guideline VDI 4630. This offers uniform rules and specifications for the practical applications of fermentations tests, which serve the operational optimisation of biogas plants. Those more interested in the basics, should search in the internet for Martin Kaltschmitt an author in regards to energy made of biomass.

FRITSCH was given the task, to process fresh grass silage with a higher degree of moisture, in a manner, so that a homogenous sample would evolve. Chosen was the Planetary Mill PULVERISETTE 6 classic line in combination with a 250 ml grinding bowl made of sintered corundum and balls of 30 mm diameter. From tests with other tough, elastic materials it is known that the slightly rough surface of sintered corundum has a very positive influence on the comminution.