Kaş, Aykut
Utilization of hyperthermophilic microorganisms was suggested to improve reaction rates and insoluble pollutant degradation and minimize the risk of contamination in bioelectrochemical systems (BESs). So far only a small group of hyperthermophilic microorganisms were identified, which show the ability to donate electrons to solid electrodes in BESs and here we present a new culture that fits to this description. The iron reducing archaeal culture Geoglobus acetivorans, originally isolated from a hydrothermal structure, produced 1.53 ± 0.24 A/m2 peak current density in microbial electrolysis cells (MECs) operated at 80 °C. This current density value is 2.5 – 3 times higher than the previously reported electro-active behavior of closely related archaeal species of Ferroglobus placidus and Geoglobus ahangari with the exact reactor configuration. Maximum hydrogen production rate (QH2) was found as 0.57 ± 0.06 m3 H2/m3*d in the 5 mL Mini-MEC reactors fed with 10mM acetate. There was a visible biofilm formation on the anode and minimum 6 cycles of biohydrogen generation coupled with high current generation was observed. Upon longer operation of reactors, biofilm started to detach from the electrode surface and both hydrogen and current production were decreased. Cyclic voltammetry (CV) analysis produced a sigmoidal catalytic wave with a mid-point potential of −0.40 V (vs. Ag/AgCl). Direct electron transfer (DET) capability by G. acetivorans was shown with peak separation analysis, rapid current density recovery after media replacement and thick biofilm formation on the anode electrode. G. acetivorans was able to utilize complex organic waste in hyperthermophilic MECs, after initial biofilm formation with acetate.


Optimising clarification of carrot juice by bacterial crude pectinase
Uzuner, Sibel; Çekmecelioğlu, Deniz (2015-12-01)
This study was undertaken to search for potential use of crude bacterial pectinase enzyme produced from Bacillus subtilis grown on hazelnut shell hydrolysate in clarification of carrot juice and to optimize the enzyme load, pH and time using the Box-Behnken response surface methodology (RSM). The carrot juice was treated with the crude pectinase enzyme (5.60 U mL(-1)) at different concentrations (0.1-0.5%), pH (4-7), and time (2-6 h). The obtained enzyme was also compared with commercial fungal pectinase at...
Organic acid production from the organic fraction of municipal solid waste in leaching bed reactors
Doğan, Evrim; Demirer, Göksel Niyazi; Department of Environmental Engineering (2006)
This study was carried out to evaluate the potential of high-rate anaerobic digestion of high-solids organic fraction of municipal solid waste (OFMSW) for the production of organic acids and alcohols in leaching bed reactors (LBRs). For this purpose, two different experimental set-ups, namely Set-1 and Set-2, were operated. In the Set-1, only OFMSW without paper was studied in two identical LBRs, whereas, four identical LBRs, fed with OFMSW with paper and cow manure in different proportions, were operated i...
Intracellular alkaline proteases produced by thermoacidophiles: detection of protease heterogeneity by gelatin zymography and polymerase chain reaction (PCR)
Kocabıyık, Semra (2002-08-01)
In this study 24 thermoacidophilic archeal and bacterial strains isolated from hot-springs and hot-soils were screened for their ability to produce intracellular alkaline proteases. The protease activities of the strains, based on azocasein hydrolysis, showed a variation from 0.6 to 5.1 U. The cell extracts of three most potent producers were further examined and it was found that their proteases exhibited maximum activity at 60-70 degreesC and showed a pH Optimum over a range of pH 7.0-8.5. Gelatin zymogra...
Nitrite and nitrate removal efficiencies of soil aquifer treatment columns
Güngör, Kerem; Ünlü, Kahraman (2005-05-20)
Bench-scale soil column experiments were performed to examine the effects of soil type and infiltration conditions on the removal efficiencies of wastewater nitrites and nitrates during the biological ripening phase of soil aquifer treatment (SAT) columns. SAT was simulated in three 1-m-high soil columns packed with 3 different natural agricultural soils having sandy clay loam (SCL), loamy sand (LS) and sandy loam (SL) textures. All columns were equipped with tensiometers and soil-water sampling ports, and ...
Anaerobic mesophilic co-digestion of sugar-beet processing wastewater and beet-pulp in batch reactors
Alkaya, Emrah; Demirer, Göksel Niyazi (2011-03-01)
In this study, biochemical methane potential (BMP) assay was conducted to investigate the effect of waste mixing and F/M ratio on the co-digestion of wastewater and beet-pulp, in addition to the digestion of the wastes separately. In the studied F/M range (0.51–2.56 g COD/g VSS), observed treatment efficiencies (63.7–87.3% COD removal and 69.6–89.3% VS reduction) were indications of high biodegradability for both wastewater and beet-pulp, which decreased with increasing F/M. It was evident that the extent o...
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