COSTA, J. W. N.; http://lattes.cnpq.br/5820878670256772; COSTA, José Williams Nogueira da.
Resumo:
In this thesis, it was tried to evaluate an operational strategy for maximizing the production o f
methane in UASB reactor treating vinasse. To this end, four UASB reactors were operated
(Ri, R2, R3 and R4) and subjected to different operational conditions. While the first two were
operated at room temperature for 130 days, the latter two were operated at a constant
temperature o f 37 °C for 60 days. The reactors Ri and R3, taken as references reactors were
operated relatively low load at high efficiency, whereas reactors R2 and R» were overload
with organic material in order to produce a sludge rich in methanogenic bacteria for high
degradation rates o f the substrate. The maximum volumetric organic load (VOC) attained in
reactor R| was 14 gCOD / L.d, with an efficiency o f organic material removal in the reactor
ranging between 58% and 92%. R2 on the other hand, showed a VOC o f 28 gCOD/L.d. with
an average efficiency o f 48%. Reactors R3 and R4, reached a maximum VOCs o f 35 and 45
gCOD / L.dia respectively, with COD removal efficiencies o f 80 and 65% respectively. The
performance o f the reactors was compared with regard to removed volumetric organic load
and methane production. The maximum VOCremoved were 11, 14, 28 And 31 gCOD / L.dia
and the maximum methane productions were 82,9, 97,1, 177.4 and 176.9 respectively for the
reactors Ri, R2, R3 and R». The characteristics of the sludge as a function of imposed
operating conditions in the reactor were assessed by specific tests for reactors Ri, R2. The
sludge reactor R2 had significant changes in the SMA (specific methanogenic activity) values
of SMA, rising from 0.44 gCOD-CHVgSVT.d at the beginning o f the operation to 0.92
gCOD-CHVgSVT.d at the end o f the operation period. The sludge o f Rj in turn did not have
the same increase in SMA values, exhibiting a maximum at 0.68 gCOD-CHVgSVT.d. This
shows that the operational strategy o f maintaining a UASB reactor overloaded, favoured the
growth o f a group o f organisms with high rates o f substrate degradation, which were shown to
be superior to microorganisms developing in the reactor operated with high removal
efficiency of organic matter. However during the trial period there was a loss o f sludge in the
reactor R2 , so that the methane production capacity did not increase in proportion to the
increase in SMA. I t was not possible to identify the reason for the loss o f sludge.