It has previously been shown that most archaea in anaerobic
digesters are methanogens (Coats et al., 2012). Our findings support
this in that we found the archaeal 16S rDNA gene copy numbers to
have a positive correlation with methane production. The highest
archaeal 16S ribosomal gene copy number for the mesophilic process
was recorded at the OLR of 5 kg VSm3 d1. This corresponded
with peak methane production of 306e432 L kg VS1. An OLR of
3 kg VS m3 d1 resulted in the highest observed archaeal 16S ribosomal
gene copy number, and a methane production of 408e
464 L kg VS1 in the thermophilic process