Treatability Of Palm Oil Mill Effluent (Pome) Using Black Liquor In An Anaerobic Treatment Process
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Date
2007-07
Authors
Ling, Yu Lang
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Abstract
Treatability studies of POME in various operational conditions were studied. A
laboratory study was carried out at thermophilic temperature (55°C) to assess and
compare the effect of two types of media, seeding and substrate on the anaerobic
digestibility of (palm oil mill effluent) POME. Chemical oxygen demand (COD) reduction
was monitored to evaluate the effect of media, seeding and substrates on the system
performance. The COD removal was up to 59.9% from the initial COD concentration of
9.30 gIL that was achieved from the digested POME digester with palm kernel shell as
a media, and fed with solubilised POME. Sodium Hydroxide (NaOH) solubilisation at
different temperature, pH and treatment time was studied to determine the best
condition for POME solubilisation in order to improve the POME treatability by
anaerobic digestion process. The COD removal efficiency increased 5.9% from 40.9%
prior solubilisation to 46.8% after solubilisation at pH 10, temperature 120°C and
retention time 90 minutes. The feasibility of anaerobic digestion treating POME with
addition of chemical pulping black liquor was studied in semi-continuous fed digesters
under thermophilic (55°C) and mesophilic (35°C) condition. The anaerobic digestibility
of raw POME and POME with addition of chemical pulping black liquor (2.5% to 20%
by volume) was compared. The chemical oxygen demand (COD) reduction for
hydraulic retention time (HRT) of 5 days and 10 days were examined to evaluate the
effect of HRT on the performance of digesters. Thermophilic anaerobic process was
more effective than mesophilic process to treat either raw POME or POME with
addition of black liquor. The experiment resulted that COD reduction up to 87.2% can
be achieved in raw POME digester at OLR 8.30 g CODIUday and the COD reduction
in black liquor added digester was 78.9% at OLR 8.67 g CODIUday under thermophilic
condition. The specific methane gas yielded from raw POME at thermophilic condition
was 0.124 to 0.066 LOWgCOD when the OLR was altered from 8.30 to 16.00 g
CODIUday. The specific methane gas yielded from POME with addition of black liquor
was ranged between 0.130 to 0.223 LcHJgCOD and 0.072 to 0.105 LCHJgCOD when the
black liquor content was altered from 2.5% to 10% at 10 days and 5 days HRT
respectively. POME with addition of 20% black liquor only achieved 0.059 and 0.018
LcHJgCOD with OLR 7.06 and 14.30 g CODIUday respectively.
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Keywords
A laboratory study was carried out at thermophilic temperature (55°C) , to assess and compare the effect of two types of media