초록
<P><B>Abstract</B></P> <P>Enhancement of biological H<SUB>2</SUB> production efficiency with pre-ozonation process of palm oil mill effluent (POME) prior to thermophilic dark fermentation (55 °C) was investigated. H<SUB>2</SUB> fermentation experiments were conducted using varying concentrations of raw and ozonated POME. Results revealed that H<SUB>2</SUB> can be produced from both raw and ozonated POME under thermophilic fermentation. Maximum H<SUB>2</SUB> production yield of 77 mL.g<SUP>−1</SUP>COD<SUB>removed</SUB> was obtained from ozonated POME, which was higher than that of 51 mL·g<SUP>−1</SUP> COD<SUB>removed</SUB> obtained from raw POME at the highest concentration of 35,000 mg COD.L<SUP>−1</SUP>. Meanwhile, the specific H<SUB>2</SUB> production rate (R'<SUB>max</SUB>) of 1.9 and 1.5 mL·h<SUP>−1</SUP>·g<SUP>−1</SUP> TVS were observed in raw and ozonated POME at the concentration of 25,000 mg COD.L<SUP>−1</SUP>, respectively. The main metabolic products during POME fermentation were acetic and butyric acids and trace amount of valeric acid. Propionic acid and ethanol have contributed, which could be reduced H<SUB>2</SUB> production in all batch experiments for both POME. The highest efficiency of total and soluble COD removal of 24 and 25% was obtained from the raw POME, and those of 19 and 25% was obtained from the ozonated POME. The present study demonstrates that the POME loading was greatly influenced on the H<SUB>2</SUB> production yields and rates. The comparative results showed that the ozonated POME gave higher H<SUB>2</SUB> yields than the raw POME. Thus, demonstrating that the ozonation process significantly improved the POME biodegradability, which is able to enhance H<SUB>2</SUB> production yields. However, the ozone pre-treatment was not improved in the specific H<SUB>2</SUB> production rates.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermophilic biohydrogen production using mesophilic mixed culture as inoculum. </LI> <LI> Maximum biohydrogen yield obtained at POME concentration of 25,000 mg COD L<SUP>-1</SUP>. </LI> <LI> Pretreatment of POME using ozone improved the biohydrogen yield. </LI> </UL> </P>