The other useful method for explaining anaerobic reactor performance
is by comparing microbial community characteristics
among different designs. qPCR was employed to estimate the relative
abundances of five important methanogen groups (i.e., defined
by Order, family and-or presumed function) and eubacterial community
sizes in the difference reactors (see Table 2). Table 4 shows
that MBT and MCC abundances were similar between reactor
‘‘seeds’’ and the ‘‘after’’ samples for all three anaerobic reactors.
However, abundances of MST, MSC, MMB, and to a lesser degree,
eubacteria were significantly lower in ‘‘after’’ samples specifically
from the HUASB and AHR reactors. This is noteworthy because
the MST, MSC and MMB were also found in low abundance in
anaerobic batch reactors treating PCP colourant wastes, which
had low methane yields (Ahammad et al., 2012). It had been speculated
that low methanogen abundances, especially MSC, resulted
from inhibition by oxidants or dyes in the colourant wastes. However,
microbial community data imply MSC are broadly important