کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1278293 | 1497546 | 2012 | 15 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Regulating biohydrogen production from wastewater by applying organic load-shock: Change in the microbial community structure and bio-electrochemical behavior over long-term operation Regulating biohydrogen production from wastewater by applying organic load-shock: Change in the microbial community structure and bio-electrochemical behavior over long-term operation](/preview/png/1278293.png)
Detailed experiments were designed to evaluate the function of load-shock treatment strategy (50 g COD/l; 3 days) for selective enrichment of acidogenic hydrogen (H2) producing consortia in comparison with untreated anaerobic consortia. Experiments performed in suspended-batch mode bioreactors for 520 days illustrated the relative efficiency of load-shock treated consortia in enhancing H2 production (16.64 mol/kg CODR) compared to untreated-parent consortia (3.31 mol/kg CODR). On the contrary, substrate degradation was higher with control operation (ξCOD, 62.86%; substrate degradation rate (SDR), 1.10 kg CODR/m3-day) compared to load-shock culture (52.33%; 0.78 kg CODR/m3-day). Fatty acid composition documented a shift in the metabolic pathway towards acetate formation after applying load-shock, which manifests higher H2 production. Microbial profiling documented a significant alteration in species composition of microbial communities after repeated load-shock applications specific to enrichment of Firmicutes which are favourable for H2 production. Dehydrogenase activity was stabilized with each re-treatment, signifying the adaptation inclination of the biocatalyst towards increased proton shuttling between metabolic intermediates, leading to higher H2 production. Voltammograms of load-shock treated cultures showed a marked shift in oxidation and reduction catalytic currents towards more positive and negative values respectively with increasing scan rate evidencing simultaneous redox-conversion reactions, facilitating proton gradient in the cell towards increased H2 production. Load-shock treatment facilitates direct cultivation of inoculums at higher substrate load without any chemical pretreatment. This study documented the feasibility of controlling microbial metabolic function by application of load-shock treatment either for preparing inoculum for startup of the reactor or to the reactor resident microflora (in situ) during operation whenever required to regain the process performance.
► Load-shock treatment (LST) influence on enriched biocatalyst was studied for 520 days.
► Acetate and butyrate type fermentations were observed with load-shock treated culture.
► Microbial inventory dehydrogenase activity and bio-electro kinetics correlated well.
► Microbial diversity of LST reactor illustrated the suppressed methanogenic activity.
► LST showed increased redox inter-conversions after load-shock showed proton gradient.
Journal: International Journal of Hydrogen Energy - Volume 37, Issue 23, December 2012, Pages 17763–17777