MICROBIOLOGICAL ASPECTS OF ANAEROBIC-DIGESTION OF SWINE SLURRY IN UPFLOW FIXED-BED DIGESTERS WITH DIFFERENT PACKING MATERIALS

Samples taken from liquid influents, liquid effluents, bottom sediments and biofilms attached to the supports of three laboratory anaerobic, fixed-bed, upflow digesters, filled with wood chips, PVC or expanded-clay support media and fed with swine slurry, were tested microbiologically. The numbers of anaerobic heterotrophic, anaerobic cellulolytic, acidogenic-peptone-glucose fermenting and methanogenic bacteria were determined. For each digester the biogas production was monitored. The highest biogas production, referred to the volatile solids concentration in the feed, was obtained in the digester with wood chips, while production was almost nil in the digester with expanded clay. © 1990.