<p>ABSTRACT</p><p>Anaerobic digestion is one way of handling biowaste and generating energy in the form of methane, biogas.</p><p>This study shows that spore forming bacterias survive the process of pasteurisation and anaerobic digestion in biogas plants. It has also been established that both the nonpasteurised-and digestion- waste contains pathogen spore forming bacterias. Two Swedish full-scale</p><p>commercial biogas plants were sampled before pasteurisation, after pasteurisation and after digestion on 10 occasions with one week intervals. The samples were analysed quantitatively</p><p>and qualitatively, with biochemical methods, for Clostridium spp and Bacillus spp.</p><p>Polymerase Chain Reaction, a biomolecular method, was used for</p><p>C. chauvei analysis, with C. chauvei specific primers. For this analyse the biogas plants were sampled at 11 occasions.</p><p>Survival of pathogenic spore forming bacteria in digestion residue may be a health risk for both humans and animals. The digested residue may be used as fertiliser on arable land and the risk of contamination by pathogenic Clostridium spp and Bacillus spp is hard to assess, but can not be neglected.</p>

ABSTRACT Anaerobic digestion is one way of handling biowaste and generating energy in the form of methane, biogas. This study shows that spore forming bacterias survive the process of pasteurisation and anaerobic digestion in biogas plants. It has also been established that both the nonpasteurised-and digestion- waste contains pathogen spore forming bacterias. Two Swedish full-scale commercial biogas plants were sampled before pasteurisation, after pasteurisation and after digestion on 10 occasions with one week intervals. The samples were analysed quantitatively and qualitatively, with biochemical methods, for Clostridium spp and Bacillus spp. Polymerase Chain Reaction, a biomolecular method, was used for C. chauvei analysis, with C. chauvei specific primers. For this analyse the biogas plants were sampled at 11 occasions. Survival of pathogenic spore forming bacteria in digestion residue may be a health risk for both humans and animals. The digested residue may be used as fertiliser on arable land and the risk of contamination by pathogenic Clostridium spp and Bacillus spp is hard to assess, but can not be neglected.