Pontypridd, United Kingdom
Pontypridd, United Kingdom

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Massanet-Nicolau J.,Sustainable Environment Research Center | Guwy A.,Sustainable Environment Research Center | Dinsdale R.,Sustainable Environment Research Center | Premier G.,University of South Wales | Esteves S.,Sustainable Environment Research Center
International Journal of Hydrogen Energy | Year: 2010

Hydrogen was produced from primary sewage biosolids via mesophilic anaerobic fermentation in a continuously fed bioreactor. Prior to fermentation the sewage biosolids were heated to 70 °C for 1 h to inactivate methanogens and during fermentation a cellulose degrading enzyme was added to improve substrate availability. Hydraulic retention times (HRT) of 18, 24, 36 and 48 h were evaluated for the duration of hydrogen production. Without sparging a hydraulic retention time of 24 h resulted in the longest period of hydrogen production (3 days), during which a hydrogen yield of 21.9 L H2 kg-1 VS added to the bioreactor was achieved. Methods of preventing the decline of hydrogen production during continuous fermentation were evaluated. Of the techniques evaluated using nitrogen gas to sparge the bioreactor contents proved to be more effective than flushing just the headspace of the bioreactor. Sparging at 0.06 L L min-1 successfully prevented a decline in hydrogen production and resulted in a yield of 27.0  L H2 kg-1 VS added, over a period of greater than 12 days or 12 HRT. The use of sparging also delayed the build up of acetic acid in the bioreactor, suggesting that it serves to inhibit homoacetogenesis and thus maintain hydrogen production. © 2009 Professor T. Nejat Veziroglu.

Kim J.R.,University of South Wales | Premier G.C.,University of South Wales | Hawkes F.R.,Sustainable Environment Research Center | Rodriguez J.,Sustainable Environment Research Center | And 2 more authors.
Bioresource Technology | Year: 2010

Energy recovery while treating low organic loads has been investigated using longitudinal tubular microbial fuel cell (MFC) reactors. Duplicate reactors, each consisting of two modules, were operated with influent sucrose organic loading rates (OLRs) between 0.04 and 0.42 g COD/l/d. Most soluble COD (sCOD) removal occurred in the first modules with predominantly VFAs reaching the second modules. Coulombic efficiency (CE) in the second modules ranged from 9% to 92% which was 3-4 times higher than the first modules. The maximum energy production was 1.75 W h/g COD in the second modules at OLR 0.24 g/l/d, up to 10 times higher than the first modules, attributable to non-fermentable substrate. A simple plug flow model of the reactors, including a generic non-electrogenic reaction competing for acetate, was developed. This modular tubular design can reproducibly distribute bioprocesses between successive modules and could be scalable, acting as a polishing stage while reducing energy requirements in wastewater treatment. © 2009 Elsevier Ltd. All rights reserved.

Kuo S.-C.,National Cheng Kung University | Chao Y.-C.,National Cheng Kung University | Tien Y.-M.,National Cheng Kung University | Chen I.-C.,National Cheng Kung University | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2011

An anaerobic fluidized bed reactor (110 L AnFBR) which kitchen waste (KW) was fed as the major substrate and different weight fractions of napiergrass dregs as the supplemental ones for bio-hydrogenation at long hydraulic retention time of 7.3 days was established. Two types of microorganisms could be distinguished by their life surroundings in the microbial community of the AnFBR: one is suspended growth, the other is attached growth. In order to evaluate the biohydrogen potential and kinetic characteristics of the two microbial growths in the AnFBR, a series of biodegradation batch experiments were conducted as the biochemical hydrogen potential test. The suspended microbe had obvious bio-hydrogen production after 3.6 h of lag phase, and the maximum specific hydrogen production rate achieved at 2.65 mmol/g-VSS-hr; the attached microbe stayed longer lag phase about 20 h and the maximum specific hydrogen production rate reached up to 1.06 mmol/g-VSS-hr. The metabolism study was investigated with volatile fatty acids conversion with initial, middle and final constitutes. The huge amount of lactic acid degradation of suspended growth (about 6000 mg/L degradation) displayed a special phenomenon in fermentative hydrogen production. Scanning electron microscope (SEM) was used to observe the morphology of two cultures. We also performed a terminal restriction fragment length polymorphism (T-RFLP) analysis for the diverse microbial identification. © 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

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