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- Hwang, JH, et al.
(författare)
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Effect of pH and sulfate concentration on hydrogen production using anaerobic mixed microflora
- 2009
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 34:24, s. 9702-9710
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Tidskriftsartikel (refereegranskat)abstract
- The effects of varying sulfate concentrations with pH on continuous fermentative hydrogen production were studied using anaerobic mixed cultures growing on a glucose substrate in a chemostat reactor. The maximum hydrogen production rate was 2.8 L/day at pH 5.5 and sulfate concentration of 3000 mg/L. Hydrogen production and residual sulfate level decreased with increasing the pH from 5.5 to 6.2. The volatile fatty acids (VFAs) and ethanol fractions in the effluent were in the order of butyric acid (HBu) > acetic acid (HAc) > ethanol > propionic acid (HPr). Fluorescence In Situ Hybridization (FISH) analysis revealed the presence of hydrogen producing bacteria (HPB) under all pH ranges while sulfate reducing bacteria (SRB) were present at pH 5.8 and 6.2. The inhibition in hydrogen production by SRB at pH 6.2 diminished entirely by lowering to pH 5.5, at which activity of SRB is substantially suppressed.
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- Bhatnagar, Amit, et al.
(författare)
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Bromate removal from water by granular ferric hydroxide (GFH)
- 2009
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 170:1, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of granular ferric hydroxide (GFH) for bromate removal from water has been studied. Batch experiments were performed to study the influence of various experimental parameters such as effect of contact time, initial bromate concentration, temperature, pH and effect of competing anions on bromate removal by GFH. The adsorption kinetics indicates that uptake rate of bromate was rapid at the beginning and 75% adsorption was completed in 5 min and equilibrium was achieved within 20 min. The sorption process was well described by pseudo-second-order kinetics. The maximum adsorption potential of GFH for bromate removal was 16.5 mg g−1 at 25 °C. The adsorption data fitted well to the Langmuir model. The increase in OH peak and absence of Br–O bonding in FTIR spectra indicate that ion-exchange was the main mechanism during bromate sorption on GFH. The effects of competing anions and solution pHs (3–9) were negligible. Results of the present study suggest that GFH can be effectively utilized for bromate removal from drinking water.
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- Bhatnagar, Amit, et al.
(författare)
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Removal of anionic dyes from water using Citrus limonum (lemon) peel: Equilibrium studies and kinetic modeling
- 2009
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Ingår i: Separation science and technology (Print). - : Informa UK Limited. - 0149-6395 .- 1520-5754. ; 44, s. 316-334
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Tidskriftsartikel (refereegranskat)abstract
- The present study was undertaken to evaluate the adsorption potential of Citrus limonum (lemon) peel as an adsorbent for the removal of two anionic dyes, Methyl orange (MO) and Congo red (CR) from aqueous solutions. The adsorption was studied as a function of contact time, initial concentration, and temperature by batch method. The adsorption capacities of lemon peel adsorbent for dyes were found 50.3 and 34.5 mg/g for MO and CR, respectively. The equilibrium adsorption data was well described by the Langmuir model. Three simplified kinetic models viz. pseudo-first-order, pseudo-second-order, and Weber and Morris intraparticle diffusion model were tested to describe the adsorption process. Kinetic parameters, rate constants, equilibrium sorption capacities, and related correlation coefficients for each kinetic model were determined. It was found that the present system of dyes adsorption on lemon peel adsorbent could be described more favorably by the pseudo-first-order kinetic model. The results of the present study reveal that lemon peel adsorbent can be fruitfully utilized as an inexpensive adsorbent for dyes removal from effluents.
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- Hwang, J.W., et al.
(författare)
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Effect of COD/SO42- ratio and Fe(II) under the variable hydraulic retention time (HRT) on fermentative hydrogen production
- 2009
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 43, s. 3525-3533
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Tidskriftsartikel (refereegranskat)abstract
- The effect of chemical oxygen demand/sulfate (COD/SO42−) ratio on fermentative hydrogen production using enriched mixed microflora has been studied. The chemostat system maintained with a substrate (glucose) concentration of 15 g COD L−1 exhibited stable H2 production at inlet sulfate concentrations of 0–20 g L−1 during 282 days. The tested COD/SO42− ratios ranged from 150 to 0.75 (with control) at pH 5.5 with hydraulic retention time (HRT) of 24, 12 and 6 h. The hydrogen production at HRT 6 h and pH 5.5 was not influenced by decreasing the COD/SO42− ratio from 150 to 15 (with control) followed by noticeable increase at COD/SO42− ratios of 5 and 3, but it was slightly decreased when the COD/SO42− ratio further decreased to 1.5 and 0.75. These results indicate that high sulfate concentrations (up to 20,000 mg L−1) would not interfere with hydrogen production under the investigated experimental conditions. Maximum hydrogen production was 2.95, 4.60 and 9.40 L day−1 with hydrogen yields of 2.0, 1.8 and 1.6 mol H2 mol−1 glucose at HRTs of 24, 12 and 6 h, respectively. The volatile fatty acid (VFA) fraction produced during the reaction was in the order of butyrate > acetate > ethanol > propionate in all experiments. Fluorescence In Situ Hybridization (FISH) analysis indicated the presence of Clostridium spp., Clostridium butyricum, Clostridium perfringens andRuminococcus flavefaciens as hydrogen producing bacteria (HPB) and absence of sulfate reducing bacteria (SRB) in our study.
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- Lee, S.H., et al.
(författare)
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Activity of Sulfate Reducing Bacteria in Successive Alkalinity Producing System: Part I- Effect of Temperature
- 2010
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Ingår i: Research Journal of Chemistry and Environment. - 0972-0626. ; 14:4, s. 67-73
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Tidskriftsartikel (refereegranskat)abstract
- Successive alkalinity producing system (SAPS) is one of the most preferred passive treatment system for acid mine drainage. Sulfate reducing bacteria (SRB) in SAPS make anaerobic environment needed to successive alkalinity production of limestone. It was observed that the SRB activity was most apparent at 36 oC and sulfate removal rate of up to 86% was achieved at this temperature when SAPS had 8 cm thickness of mushroom compost layer and hydraulic retention time (HRT) of 8 days. The sulfate removal rate was directly proportional to the temperature and it significantly decreased at 1 oC. The unexpected observation on the increased effluent sulfate concentration at 1 oC was due to the effect of sulfate elution from the mushroom compost. Iron removal rate was governed by both temperature and thickness of the mushroom compost layer. Finally, cultivation experiments revealed that SRB growth was significantly influenced by the temperature. The results of the present study suggest that the temperature directly influences on the SRB growth and subsequently controls the treatment efficiency of SAPS.
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