Sequential batch operation was shown to be very effective
in converting high concentrations of VFAs produced
in start-up reactors to methane in mature reactors. By
increasing the leachate exchange rate between mature and
start-up reactors, the time to reach methanogenesis in
start-up reactors decreased markedly. As a result a greater
number of batches of waste may be digested in a shorter
time frame, leading to overall increased methane
productivity.
There is a need to continue the investigation into the
optimisation of the sequential batch system, as the loading
thresholds for mature reactors in these systems has
yet to be determined. The current findings suggest that
the leachate exchange process can be optimised based
on easily identifiable changes in biogas composition
within mature reactors coupled with start-up reactors.
The use of process monitoring parameters such as pH
and biogas composition is advantageous as they are reliable,
and quickly and easily determined. This is important
for waste processors that do not have access to
more specialised equipment to determine VFA concentration
or investigate the microbial community. There is also
scope to utilise different high calorie feedstocks such as
waste streams from food processing plants in the sequential
batch system