초록
<P><B>Abstract</B></P> <P>The effect of trace metals supplementation into palm oil mill effluent on biohythane production and responsible microbial communities in thermophilic two-stage anaerobic fermentation was investigated. High biohythane yields were linked to Ni/Co/Fe supplementation (10, 6 and 20 mg L<SUP>−1</SUP>, respectively) with maximum H<SUB>2</SUB> and CH<SUB>4</SUB> yields of 139 mL H<SUB>2</SUB> gVS<SUP>−1</SUP> and 454 mL CH<SUB>4</SUB> gVS<SUP>−1</SUP>, respectively. The Ni/Co/Fe supplementation resulted in higher numbers of <I>Bacillus</I> sp., <I>Clostridium</I> sp. and <I>Thermoanaerobacterium</I> sp. together with increasing hydrogenase expression level leading to increasing hydrogen yields of 90.4%. The numbers of <I>Methanosarcina</I>, <I>Methanomassiliicoccus</I>, and <I>Methanoculleus</I> were enhanced by Ni/Co/Fe addition, accompanied by 21.7% higher methane yields. No correlation between methyl coenzyme-M reductase expression level and methane yields was observed. The Ni/Co/Fe supplementation improved gas production in the two-stage biohythane process via enhancing a number of viable hydrogen-producing bacteria together with hydrogenase activity in H<SUB>2</SUB> stage and enhancing number methanogens in the CH<SUB>4</SUB> stage.</P> <P><B>Highlights</B></P> <P> <UL> <LI> POME supplemented with Ni, Fe and Co increased 90.4% hydrogen yield. </LI> <LI> POME supplemented with Ni, Fe and Co increased 21.7% methane yield. </LI> <LI> Optimal concentration of Ni, Co and Fe is 10, 6 and 20 mg L<SUP>−1</SUP>. </LI> <LI> Hydrogen-producing bacteria growth and hydrogenase activity was enhanced. </LI> <LI> Methanogens growth was stimulated by Ni, Fe and Co addition. </LI> </UL> </P>