Effect of organic loading on a novel hydrogen bioreactor

Bio-hydrogen production from thin stillage using conventional and acclimatized anaerobic digester sludge

“…The maximum SHPR for batches using AADS was 585 mL H 2 /gVSS.d at an S 0 /X 0 ratio of 6 gCOD/ gVSS while in batches using ADS the maximum only reached 181 mL H 2 /gVSS.d at S 0 /X 0 ratio of 4 gCOD/gVSS. Hafez et al [10] observed the same pattern of a maximum SHPR followed by a sharp decline at high S 0 /X 0 ratio using the authors' data as well as seven other literature studies. The findings of this study contradicts the observations of Jiunn et al [34] who studied hydrogen production using organic fraction of municipal solid waste (OFMSW) as the substrate and two types of sludges at different mixing ratios; i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 6 ( 2 0 1 1 ) 1 2 7 6 1 e1 2 7 6 9 pre-treated anaerobic digester sludge and acclimatized sludge from a hydrogen producing chemostat reactor with an HRT of 10 h and sucrose as the substrate, and reported no trend for the SHPR with increasing the acclimated sludge percentage.…”

“…The total suspended solids (TSS) and volatile suspended solids (VSS) concentrations of the ADS were 22.9 and 13.2 g/L respectively. Heat pretreatment for the ADS was conducted by heating the sludge at 70 0 C for 30 min [10]. AADS was collected from a continuous-flow biohydrogen system with aforementioned ADS seed.…”

“…The total genomic community DNA was extracted using UltraClean Soil DNA Isolation Kit (MO BIO Laboratories, Carlsbad, CA, USA) and after PCR amplification were analyzed by denaturing gradient gel electrophoresis (DGGE). For further details refer to Hafez et al [10].…”

“…The optimum hydraulic retention time (HRT) for biohydrogen production ranges from 4 to 8 h [9,10]. Furthermore, the food-to-microorganisms (F/M) ratio is a critical parameter that affects hydrogen production with hydrogen yield increasing linearly at F/M ratios of 4e6.6 gCOD/ gVSS.d [10].…”

“…Pretreatment of anaerobic digester sludge is required primarily to restrain the hydrogen consuming bacteria and enrich the hydrogen producing bacteria, and this can be done by several methods such as heat, acid, base, aeration, or ultrasonication pretreatment [28]. Acclimatization of anaerobic digester sludge to enrich the hydrogen producers in a hydrogen bioreactor, where methanogens are washed out and hydrogen producers become the predominant community in the sludge in continuous-flow systems [10,29], is the most representative microbial culture for assessment of biohydrogen production potential from various substrates. An extensive search in Google Scholar, Scifinder, and Engineering Village data bases using keywords "biohydrogen production, acclimated sludge, acclimatized sludge, anaerobic digester sludge, fermentative hydrogen batches" revealed that no previous work has been conducted on hydrogen production in batch experiments using acclimatized anaerobic digester sludge from a continuous-flow biohydrogen system.…”