초록
<P><B>Abstract</B></P> <P>A two-stage thermophilic fermentation and mesophilic methanogenic process for biohythane production from palm oil mill effluent (POME) was investigated. The hydrogen and methane potential from POME were 170–200 L H<SUB>2</SUB> kgCOD<SUP>−1</SUP> and 210–292 L CH<SUB>4</SUB> kgCOD<SUP>−1</SUP>, respectively. A continuous two-stage process with hydraulic retention time (HRT) of 2 d for hydrogen reactor and 15 d for methane reactor, obtained 34% higher energy yield than single stage methane production. The hydrogen and methane yields from two-stage were 210 L H<SUB>2</SUB> kgCOD<SUP>−1</SUP> and 315 L CH<SUB>4</SUB> kgCOD<SUP>−1</SUP>, respectively with total energy yield of 15.34 MJ kgCOD<SUP>−1</SUP>. Mixed hydrogen and methane (biohythane) production rate was 4.4 L biogas L<SUP>−1</SUP>d<SUP>−1</SUP> with containing of 51% CH<SUB>4</SUB>, 14% H<SUB>2</SUB> and 35% CO<SUB>2</SUB>. Hydrogen reactor was dominated with hydrogen producing bacteria of <I>Thermoanaerobacterium thermosaccharolyticum</I>, while acetoclastic <I>Methanoculleus</I> sp. was the dominant methanogen in methane reactor. Two-stage process for biohythane production could efficiently for energy recovery from POME.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two-stage for biohythane production from palm oil mill effluent was investigated. </LI> <LI> Hydrogen and methane yield were 170–200 L H<SUB>2</SUB> kgCOD<SUP>−1</SUP> and 210–292 L CH<SUB>4</SUB> kgCOD<SUP>−1</SUP>. </LI> <LI> Biohythane production was 4.4 L biogas L<SUP>−1</SUP> d<SUP>−1</SUP> with 51% CH<SUB>4</SUB>, 14% H<SUB>2</SUB> and 35% CO<SUB>2</SUB>. </LI> <LI> Two-stage process has 34% higher energy yield than one stage methane production. </LI> <LI> Two-stage process for biohythane production could efficiently for energy recovery. </LI> </UL> </P>