Moitzi


Die Bodenkultur - Journal for Land Management, Food and Environment

G. Moitzi, V. Kryvoruchko, B. Amon, T. Amon und J. Boxberger:

Separation of pig slurry and the effects on NH3, N2O und CH4 emissions during storage of liquid phase and compostable solid phase

Summary

Slurry separation is a mechanical process which separates solids from liquid manure. Under field conditions the trace gases ammonia (NH3), nitrous oxide (N2O), methane (CH4) und carbon dioxide (CO2) were collected during composting of the solid fraction and storage of the liquid fraction with a mobile open-dynamic chamber and continuously analyzed with a high-resolution FTIR-spectrometer. In a summer and winter trial, separated solids (3980 kg respectively 4450 kg) from pig slurry were composted on a concrete floor. The microbial composting process reduced the organic matter by 68 % respectively 54 %. The intensive turning activities (7 times resp. 10 times) resulted in three characteristic emission phases: In the first two weeks there was an increased votalisation of NH3 – afterwards elevated CH4 emissions were observed. The anaerobic “hot spots” created favourable conditions for denitrification with the generation of N2O. The calculated Global Warming Potential (GWP) was 66 kg for the winter trial and 122.5 kg CO2 eq t-1 solid matter for the summer trial, whereby 73 % respectively 56 % resulted from N2O emissions. The aggre - gated NH3 emissions from the liquid fraction and from the composted solid fraction were 1.9 respectively 3.0 times higher than from the untreated pig slurry, mainly caused by the high NH3 emissions at the beginning of the composting process. The calculated GWP was 1.7 respectively 2.1 times higher than from the untreated pig slurry.

Key words: slurry separation, composting, trace-gas emissions, open dynamic chamber method.