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The study explored slaughterhouse waste (SHW) as prime feedstock associated with and without supplement of an external slowly degradable lignocellulosic carbon source to overcome the synergistic co-inhibitions of ammonia and fatty acids. Long-term solid-state digestion (SSD) and liquid-state digestion (LSD) were investigated using a mixture of pork liver and fat. At 2.0 g volatile solids (VS) L

Hydrogenotrophic biomethanation in a biotrickling filter has been reported to be a proven technology for biological biogas upgrading in recent studies. However, the preparation of enriched hydrogenotrophic methanogens in a separate reactor prior to biomethanation in a trickled bed is a lengthy procedure and therefore hard to apply on an industrial scale. This study explored the direct inoculation of anaerobic biogas digestate for simultaneous enrichment of hydrogenotrophic methanogens and biofilm immobilisation in a trickled bed system. The direct inoculation and formation of hydrogenotrophic biofilm was successful and resulted in a stable H 2 loading rate of 11 Nm H 2 3m R -3d -1, with the highest specific methane productivity recorded at 3.03 Nm 3m R -3d -1 and a purity of 98% CH 4 in thermophilic conditions. The DNA analysis confirmed that hydrogenotrophic methanogens dominated the archaeal consortia.

The suitability of municipal plant waste for anaerobic digestion was examined using 57 different herbaceousand non-herbaceous samples. Biochemical methane potential (BMP) and anaerobic biodegradabilitywere related to the degree of lignification and crystallinity of cellulose. The BMP of herbaceous gardenplants (332.7 CH4 NL kg VS1) was high, although lower than that of energy crops (400–475 CH4NL kg VS1). Herbaceous wild plants from natural grassland contained most lignocelluloses, leading torelatively low BMP (214.0 CH4 NL kg VS1). Non-herbaceous phytomass had a high degree of lignificationand a high concentration of crystalline cellulose, but due to the content of non-woody parts with a lowconcentration of lignocellulose the BMP was relatively high, 199.9 and 172.0 CH4 NL kg VS1 for hedgecuttings and woody cuttings, respectively. There were indications that a plant lignin concentration of100 g kg VS1 is the critical biodegradability point in anaerobic digestion of phytomass.