Effect of temperature and initial pH on biohydrogen production from palm oil mill effluent: long-term evaluation and microbial community analysis

Abstract

Anaerobic sludge from palm oil mill effluent (POME) treatment plant was used as a source of inocula for the conversion of POME into hydrogen. Optimization of temperature and initial pH for biohydrogen production from POME was investigated by response surface methodology. Temperature of 60ºC and initial pHof 5.5 was optimized for anaerobic microflora which gave a maximum hydrogen production of 4820 ml H2/l-POME corresponding to hydrogen yield of 243 ml H2/g-sugar. Total sugar consumption and chemical oxygen demand (COD) removal efficiency were 98.7% and 46%, respectively. Long-term hydrogen production in continuous reactor at HRT of 2 days, 1 day and 12 hrs were 4850 ± 90, 4660 ± 99 and 2590 ± 120 ml H2/l-POME, respectively. Phylogenetic analysis of the mixed culture revealed that members involved hydrogen producers in both batch and continuous reactors were phylogenetically related to the Thermoanaerobacterium thermosaccharolyticum. Batch reactor showed more diversity of microorganisms than continuous reactor. Microbial community structure of batch reactor was comprised of T. thermosaccharolyticum, T. bryantii, Thermoanaerobacterium sp., Clostridium thermopalmarium and Clostridium NS5-4, while continuous reactor was comprised of T. thermosaccharolyticum, T. bryantii and Thermoanaerobacterium sp. POME is good substrate for biohydrogen production under thermophilic condition with Thermoanaerobacterium species play an important role in hydrogen fermentation.

Simultaneous thermophilic hydrogen production and phenol removal from palm oil mill effluent by Thermoanaerobacterium-rich sludge

“…The hydrogen production at HRT of 2 and 1 day were 4.2 and 4.0 L H 2 /L-POME, respectively. This hydrogen production was comparable with those of previous report; 4.7 L H 2 /L-POME [32], 4.8 L H 2 /L-POME [20] and 4 L H 2 /L-POME [33]. The phenol removal efficiency at HRT 2 and 1 day were 92% and 85%, respectively (Fig.…”

“…Khanal et al [28] reported that pH is a pivotal parameter for biohydrogen production and suggested that pH 5.5 was the optimum initial pH for hydrogen production. O-Thong et al [20] also reported that pH 5.5 and temperature of 60 C were optimum for hydrogen production from POME by Thermoanaerobacterium-rich sludge. Effect of phenol concentration on Thermoanaerobacteriumrich sludge was test in POME adjusted pH to 5.5 and augmenting phenol at 100e1000 mg/L.…”

“…A non-defined culture, Thermoanaerobacterium-rich sludge used in this experiment was obtained from a lab-scale anaerobic sequencing batch reactor producing hydrogen from POME at 60 C [20]. A microbial community of this sludge was analyzed by DGGE according to Hniman et al [21].…”

“…Thermoanaerobacterium-rich sludge has been used for hydrogen production from POME with hydrogen production of 4.6 L H 2 /L-POME [20]. Thermoanaerobacterium-rich sludge comprised of Thermoanaerobacterium thermosaccharolyticum, Thermoanaerobacterium bryantii, Thermoanaerobacterium sp., Clostridium thermopalmarium and Clostridium NS5-4 which is an efficient hydrogen producers.…”

“…Thermoanaerobacterium-rich sludge comprised of Thermoanaerobacterium thermosaccharolyticum, Thermoanaerobacterium bryantii, Thermoanaerobacterium sp., Clostridium thermopalmarium and Clostridium NS5-4 which is an efficient hydrogen producers. O-Thong et al [1,20] reported that POME is good substrate for hydrogen production by Thermoanaerobacterium species under thermophilic condition. Thus, it is of practical interest to evaluate the performance of Thermoanaerobacterium-rich sludge for simultaneous hydrogen production and phenol degradation from POME under thermophilic condition.…”