The influence of the pig manure separation system on the energy production potentials

Energy recovery from pig manure offers an opportunity for waste utilisation and financial benefit. Samples of the solid fraction of separated pig manure and samples which had undergone chemical or biological pretreatment prior to separation were pyrolysed. A beech wood sample was pyrolysed for comparison. The chemically pre-treated and anaerobically digested materials had similar properties and showed similar behaviour during thermogravimetric analysis. However, the energy content of the gas arising from pyrolysis in a batch reactor at 600 °C comprises about 30% of the original energy of the feedstock in the case of the anaerobically digested materials and double that of the chemically pre-treated material. Therefore, the overall energy balance showed a loss of 595.9 MJ/t for the pyrolysis of the chemically pre-treated manure, while very small positive values of 351.7 MJ/t, 817.3 MJ/t and a significant value of 8935 MJ/t were found for anaerobically digested sample, un-pretreated solid and for wood, respectively.