Biological hydrogen production using a membrane bioreactor

Abstract

A cross-flow membrane was coupled to a chemostat to create an anaerobic membrane bioreactor (MBR) for biological hydrogen production. The reactor was fed glucose (10,000 mg/L) and inoculated with a soil inoculum heat-treated to kill non-spore-forming methanogens. Hydrogen gas was consistently produced at a concentration of 57-60% in the headspace under all conditions. When operated in chemostat mode (no flow through the membrane) at a hydraulic retention time (HRT) of 3.3 h, 90% of the glucose was removed, producing 2200 mg/L of cells and 500 mL/h of biogas. When operated in MBR mode, the solids retention time (SRT) was increased to SRT = 12 h producing a solids concentration in the reactor of 5800 mg/L. This SRT increased the overall glucose utilization (98%), the biogas production rate (640 mL/h), and the conversion efficiency of glucose-to-hydrogen from 22% (no MBR) to 25% (based on a maximum of 4 mol-H(2)/mol-glucose). When the SRT was increased from 5 h to 48 h, glucose utilization (99%) and biomass concentrations (8,800 +/- 600 mg/L) both increased. However, the biogas production decreased (310 +/- 40 mL/h) and the glucose-to-hydrogen conversion efficiency decreased from 37 +/- 4% to 18 +/- 3%. Sustained permeate flows through the membrane were in the range of 57 to 60 L/m(2) h for three different membrane pore sizes (0.3, 0.5, and 0.8 microm). Most (93.7% to 99.3%) of the membrane resistance was due to internal fouling and the reversible cake resistance, and not the membrane itself. Regular backpulsing was essential for maintaining permeate flux through the membrane. Analysis of DNA sequences using ribosomal intergenic spacer analysis indicated bacteria were most closely related to members of Clostridiaceae and Flexibacteraceae, including Clostridium acidisoli CAC237756 (97%), Linmingia china AF481148 (97%), and Cytophaga sp. MDA2507 AF238333 (99%). No PCR amplification of 16s rRNA genes was obtained when archaea-specific primers were used.

Enhancement of Biohydrogen Production via Thermophilic Cell Culture Immobilized on Glass Beads and Raschig Rings of Different Sizes in a Packed Bed Reactor

“…). The hydrogen content of the headspace in each reactor varied between 30-55 %, which is in accordance with literature 17 . The best H 2 content in terms of % was 54 % obtained from SSG at 3 h HRT.…”

“…For this purpose, four different immobilization glass materials (LSR, SSR, SSG and LSG) were comparatively tested under conditions of continuous operation. The mixed culture used as inoculum throughout the study was thermally pretreated to prepare and enrich the hydrogen-producing bacteria in the mixed consortium, as suggested by several reports 6,8,12,[17][18][19] . Complex substrates such as cellulose,lignocellulosic materials, and starch as in their raw formare not suitable for the fermentative production of hydrogen because of their nature.…”

Achieving high-rate hydrogen recovery from wastewater using customizable alginate polymer gel matrices encapsulating biomass

“…State-of-the-art technologies, such as granulation, attached growth systems, and anaerobic membrane bioreactors, retain biomass, separating the solids (or biomass) retention time (SRT) from the hydraulic retention time (HRT); this reduces the risk of biomass washout and enables more flexible process control. 7,13,14,[19][20][21] These systems, however, still provide little control over the microbial community present or biomass concentration. 22,23 This leads to organisms outcompeting desired phenotypes with a loss of resource production.…”

Algal Biofuels: A Credible Prospective?

“…It is therefore more practical to use the renewable electricity directly, although water electrolysis may play an important role as a storage technology for intermittent renewable resources. Research has also intensified in the area of artificial photosynthesis, with contributions from the fields of synthetic biology [8,9], biomimetics [10,11], electrochemistry [12,13], and many others. The problem with this approach is not only that natural photosynthesis is extremely complex, but that many of the proteins and enzymes involved in the processes of light harvesting, water splitting, and CO 2 reduction are already very efficient, having been moulded and perfected by 2.5 billion years of evolutionary pressure.…”