The effluent from UASB reactor often contains residual COD and TSS that must be
further reduced through post treatment so as to meet effluent disposal standards. In this
study, Effective Microorganisms (EM) consortium was inoculated at the ratio of 1:500 in
the UASB reactors to ascertain its impact on improving removal efficiency of both COD
and TSS. Laboratory scale UASB reactors with effective volume of 4L made of PVC pipe
with internal diameter of 100mm were used. Three experimental set-ups were organized
and operated for 60 days to investigate not only performance of the reactor but also to
investigate the best configuration for EM consortium inoculation. Set-up A comprised of
two individual reactors without and with EM (R1 and R2 respectively); Set-up B (R2*) and
Set-up C (R3) both comprised of two sequential reactors where EM consortium was
injected at the inlet of the second reactor and first reactor.
The findings of the experiment showed a significant contribution of EM consortium to the
removal efficiency in R2, R2* and R3 reactors compared to conventional UASB reactor
(R1) whereby the COD removal were 85±10%, 84±14%, 85±15% and 76±13%
respectively. Similarly TSS removal was 90±9%, 91±9%, 91±9% and 82±13%
correspondingly. However, reactors inoculated with EM showed insignificant impact in
performance regardless of reactor configuration. Similar results were generally obtained
for all forms of COD fractions. The COD mass balance depicted that EM consortium was
not consumed as a substrate but rather enhanced bioconversion anaerobic processes in
the UASB reactor.
This study shows that EM consortium can be applied in the UASB reactor to improve
removal efficiency of COD and TSS so as to produce better effluent quality of the
wastewater, which has less pollution load for consequent post treatment. However, more
research is needed to study the optimum percentage removal of these pollutants to the
extent that the post-treatment might not be necessary.