Impact of composts produced from waste of animal origin on the biological activity of soils

<p class=MsoNormal align=left style='text-align:left;mso-layout-grid-align: none;text-autospace:none'>Due to changes in the Hungarian legislation, the ATEVSZOLG Corporation, which treats waste of animal origin, has started to search for a new way to dispose and reuse this waste by recycling it without the loss of materials produced at high cost from the natural cycle. Since this waste contains a high concentration of fat, one major objective of the composting experiment was to investigate the effect of composts with high fat contents on the biological activity of the soil. The other aim was to investigate the impact of sterilising heat treatment and of high temperature conditions during the composting process on the number of pathogenic microbes, which are common in waste of animal origin. The quality and quantity of the fat in the soil samples were measured using a gas chromatograph. The effect of the high fat content on the biological activity of the soil was measured as the difference between the control and the treated soil samples for CFU number of fat-degrading microbes and the difference in the biological activity of the samples in an Oxi-Top soil respirator system. The effect of heat treatment on pathogenic microbes was investigated on the basis of the number of <i>Clostridium</i>, faecal coliforms and <i>Pseudomonas aeruginosa</i> microbes. The results showed that the high fat content deposited with the composts was well utilised, and that its degradation did not cause a problem for the microbes living in the soil. This was proved both by the results of the CFU experiments and by the parameters in the Oxi-Top soil respirator system. The heat treatment successfully decreased the number of pathogenic microbes to a low risk level. The results indicated that the mixing of the heat-treated, sterilised basic materials of the composts with untreated, non-sterilised materials such as sewage sludge should be avoided, due to the risk of re-infecting the compost with pathogens. The composts produced from animal waste using the heat treatment developed by the ATEVSZOLG Corp. have the same infection risk as the composts produced from animal manure or sewage sludge.</p> <p class=MsoNormal> </p>