Thermo-alcalic NiX-pretreatment of animal manure for biogas production

The time schedule of the project has been shortened markedly compared to the original project application, as the project activities
were executed significantly faster than expected. This was not least due to the fact that no major changes in the setup
of construction of the pressure cooking plant were necessary, which is why the project partner LM Stålindustri was not directly
involved in the project.

During the first part of the project (second half-year of 2010) pressure cooking experiments were carried out on a number of
different manure types using the patented NIX-technology. The effect of pressure cooking on gas yield and nitrogen removal,
respectively, was investigated by anaerobic digestion tests in batch bottles and nitrogen analysis in the lab. The experiments
have defined optimal process parameters for pressure cooking of animal manure with respect to temperature/pressure and
base dosage while other parameters (retention time, rate of pressure release and mixing) were not fully optimised.

Substantial gas yield improvements have been documented for all tested manure types and on average 65 % of the ammonium pool is removed. The gas yield was increased by 20 to 35 % compared to final yield and by 25 to 45 % compared to calculated yields
at typical retention times at full scale biogas plants.

In the first half-year of 2011 a continuous digestion experiment based on NiX-treated chicken litter was carried out in pilot
scale. This part of the project was not completely finalized at the end of the project period but showed results documenting
the effect of the NiX-treatment on the possibility to minimize water consumption for dilution of chicken litter during mondigestion.