Tag Archives: digestate

xxx M. Dąbrowska, A. Świętochowski and A. Lisowski
Physicochemical properties and agglomeration parameters of biogas digestate with addition of calcium carbonate
Abstract |
Full text PDF (534 KB)

Physicochemical properties and agglomeration parameters of biogas digestate with addition of calcium carbonate

M. Dąbrowska*, A. Świętochowski and A. Lisowski

Warsaw University of Life Sciences, Department of Agricultural and Forestry Machinery,
Faculty of Production Engineering, Nowoursynowska 166, PL02-787 Warsaw, Poland
*Correspondence: magdalena_dabrowska@sggw.pl

Abstract:

The aim of the work was to determine the physical properties of digestate from biogas production – either with or without the addition of calcium carbonate and to determine the parameters of its compaction. The material for research was obtained from an agricultural biogas plant specialized in processing cattle manure, vegetable pomace, chicken manure and maize silage. The parameters of compaction of digestate were experimentally determined and its net calorific value was calculated based on the gross calorific value. Physical properties were determined according to standards. The moisture content of liquid digestate was 96%. Mechanical separation allowed to decrease the water content by 19% and addition of 20% of calcium carbonate by 30%. It was found that digestate with addition of calcium carbonate is not suitable to use for energy purposes, because of its low net calorific value (5.2–5.9 MJ kg-1), however it can be used for fertilizer purposes in relation to its chemical composition. Without  additives, the net calorific value was 14.9 MJ kg-1, but due to the high moisture content of the raw material it is unprofitable to dry it and burn. On the other hand, it was proved that it is possible to obtain pellets of appropriate density out of the digestate using 40 mm of the die height and 0.3 g of single portion of the material.

Key words:

, , , ,




22-40 F. da Borso, C. Di Marzo, F. Zuliani, F. Danuso and M. Baldini
Harvest time and ensilage suitability of giant reed and miscanthus for bio-methane production and characterization of digestate for agronomic use
Abstract |

Harvest time and ensilage suitability of giant reed and miscanthus for bio-methane production and characterization of digestate for agronomic use

F. da Borso, C. Di Marzo, F. Zuliani, F. Danuso and M. Baldini*

Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Via delle Scienze, 206, IT33100 Udine, Italy
*Correspondence: mario.baldini@uniud.it

Abstract:

In many countries, biogas plants are mainly fed by livestock slurry and dedicated crops, including maize, which still represents one of the main energy crops utilized. Many concerns are now arising on environmental impact due to the high water consumption, chemical fertilizer and pesticide requirements and on adverse effect of maize as energy crop on the price of food and feed commodities. For these reasons two perennial crops, in particular miscanthus (Miscanthus x giganteus) and giant reed (Arundo donax L.), were cultivated at very low input and evaluated for their bio-methane yield at different harvest times and ensilage suitability, in a north-eastern area of Italy. Moreover, considering the agronomic use of the obtained digestate as fertilizer, this has been characterized by the content of heavy metals. Both multi-annual crops have proved highly productive in biomass especially with a harvest time in autumn, at which a satisfactory completion of the silage process without additives was observed. Conversely, bio-methane yield per hectare were not satisfactory with respect to the reference crops such as maize. The low BMP attained showed the main bottleneck of the methanisation of ensiled giant-reed and miscanthus, which is represented by fiber composition with high degree of lignification. The simulation use of digestate obtained as fertilizer in vulnerable areas, could lead to slightly exceed the levels allowed by the legislation of some European countries with regard of heavy metals as Cu, Zn and Cd.

Key words:

, , , , ,