The Experts below are selected from a list of 13842 Experts worldwide ranked by ideXlab platform
Marcelo Zaiat - One of the best experts on this subject based on the ideXlab platform.
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the use of the carbon nitrogen ratio and specific Organic Loading Rate as tools for improving biohydrogen production in fixed bed reactors
Biotechnology Reports, 2015Co-Authors: Melida Del Pilar Anzolarojas, Samantha Goncalves Da Fonseca, C Silva, Valeria Maia De Oliveira, Marcelo ZaiatAbstract:Abstract This study assessed the effect of the carbon/nitrogen (C/N) ratio on the hydrogen production from sucrose-based synthetic wastewater in upflow fixed-bed anaerobic reactors. C/N ratios of 40, 90, 140, and 190 (g C/g N) were studied using sucrose and urea as the carbon and nitrogen sources, respectively. An optimum hydrogen yield of 3.5 mol H 2 mol −1 sucrose was obtained for a C/N ratio of 137 by means of mathematical adjustment. For all C/N ratios, the sucrose removal efficiency reached values greater than 80% and was stable after the transient stage. However, biogas production was not stable at all C/N ratios as a consequence of the continuous decreasing of the specific Organic Loading Rate (SOLR) when the biomass accumulated in the fixed-bed, causing the proliferation of H 2 -consuming microorganisms. It was found that the application of a constant SOLR of 6.0 g sucrose g −1 VSS d −1 stabilized the system.
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The application of an innovative continuous multiple tube reactor as a stRategy to control the specific Organic Loading Rate for biohydrogen production by dark fermentation
Bioresource Technology, 2015Co-Authors: Simone D. Gomes, Eduardo Dellosso Penteado, Shaiane D.m. Lucas, Jackeline T. Gotardo, Lucas Tadeu Fuess, Marcelo ZaiatAbstract:Biohydrogen production in fixed-bed reactors often leads to unstable and decreasing patterns because the excessive accumulation of biomass in the bed negatively affects the specific Organic Loading Rate (SOLR) applied to the reactor. In this context, an innovative reactor configuration, i.e., the continuous multiple tube reactor (CMTR), was assessed in an attempt to better control the SOLR for biohydrogen production. The CMTR provides a continuous discharge of biomass, preventing the accumulation of solids in the long-term. Sucrose was used as the carbon source and mesophilic temperature conditions (25°C) were applied in three continuous assays. The reactor showed better performance when support material was placed in the outlet chamber to enhance biomass retention within the reactor. Although the SOLR could not be effectively controlled, reaching values usually higher than 10gsucroseg-1VSSd-1, the volumetric hydrogen production and molar hydrogen production Rates peaked, respectively, at 1470mLH2L-1d-1 and 45mmolH2d-1, indicating that the CMTR was a suitable configuration for biohydrogen production.
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effect of Organic Loading Rate on hydrogen production from sugarcane vinasse in thermophilic acidogenic packed bed reactors
International Journal of Hydrogen Energy, 2014Co-Authors: Antonio Djalma Nunes Ferraz, Jorge Wenzel, Claudia Etchebehere, Marcelo ZaiatAbstract:Abstract This study evaluated the effect of Organic Loading Rate (OLR) on hydrogen production in up-flow anaerobic packed bed reactors (APBR) continuously fed with sugarcane vinasse. Four thermophilic up-flow APBR were opeRated in parallel at different ORL. Continuous hydrogen production was detected. The optimum OLR of 84.2 kg-COD m−3 d−1 was assessed by polynomial adjustment, which predicted a maximum Volumetric Hydrogen Production (VHP) and hydrogen yield ( Y H 2 ) of 1117.2 mL-H2 d−1 L−1reactor and 2.4 mol-H2 mol−1total carbohydRates, respectively. The microbial composition was monitored using 16S rRNA gene by Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis and quantification of Fe-hydrogenase gene by real-time PCR which was affected by the OLR. The number of the Fe-hydrogenase genes was proportional to the monitored hydrogen production and yield. Hydrogen-producing strains were isolated, and the 16S rRNA gene sequences were highly homologous to those of Thermoanaerobacterium thermosaccarolyticum. The ability of vinasse as substRate for hydrogen production was confirmed for both strains.
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impact of Organic Loading Rate on biohydrogen production in an up flow anaerobic packed bed reactor uanpbr
Bioresource Technology, 2014Co-Authors: Marcelo Zaiat, Antonio Djalma Nunes Ferraz, Medhavi Gupta, Elsayed Elbeshbishy, Hisham Hafez, George NakhlaAbstract:Abstract This study assesses the impact of Organic Loading Rate on biohydrogen production from glucose in an up-flow anaerobic packed bed reactor (UAnPBR). Two mesophilic UAPBRs (UAnPBR1 and 2) were tested at Organic Loading Rates (OLRs) ranging from 6.5 to 51.4 gCOD L −1 d −1 . To overcome biomass washout, design modifications were made in the UAnPBR2 to include a settling zone to capture the detached biomass. The design modifications in UAnPBR2 increased the average hydrogen yield from 0.98 to 2.0 mol-H 2 mol −1 -glucose at an OLR of 25.7 gCOD L −1 d −1 . Although, a maximum hydrogen production Rate of 23.4 ± 0.9 L H 2 L −1 d −1 was achieved in the UAnPBR2 at an OLR of 51.4 gCOD L −1 d −1 , the hydrogen yield dropped by 50% to around 1 mol-H 2 mol −1 -glucose. The microbiological analysis (PCR/DGGE) showed that the biohydrogen production was due to the presence of the hydrogen and volatile acid producers such as Clostridium beijerinckii , Clostridium butyricum , Megasphaera elsdenii and Propionispira arboris .
Like Wang - One of the best experts on this subject based on the ideXlab platform.
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effects of temperature and Organic Loading Rate on the performance and microbial community of anaerobic co digestion of waste activated sludge and food waste
Chemosphere, 2014Co-Authors: Chengliu Gou, Zhaohui Yang, Jing Huang, Huiling Wang, Haiyin Xu, Like WangAbstract:Abstract Anaerobic co-digestion of waste activated sludge and food waste was investigated semi-continuously using continuously stirred tank reactors. Results showed that the performance of co-digestion system was distinctly influenced by temperature and Organic Loading Rate (OLR) in terms of gas production Rate (GPR), methane yield, volatile solids (VS) removal efficiency and the system stability. The highest GPR at 55 °C was 1.6 and 1.3 times higher than that at 35 and 45 °C with the OLR of 1 g VS L −1 d −1 , and the corresponding average CH 4 yields were 0.40, 0.26 and 0.30 L CH 4 g −1 VS added , respectively. The thermophilic system exhibited the best load bearing capacity at extremely high OLR of 7 g VS L −1 d −1 , while the mesophilic system showed the best process stability at low OLRs ( −1 d −1 ). Temperature had a more remarkable effect on the richness and diversity of microbial populations than the OLR.
Marcell Nikolausz - One of the best experts on this subject based on the ideXlab platform.
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reduction of the hydraulic retention time at constant high Organic Loading Rate to reach the microbial limits of anaerobic digestion in various reactor systems
Bioresource Technology, 2016Co-Authors: Ayrat M Ziganshin, Zuopeng Lv, Thomas Schmidt, Jan Liebetrau, Hans H Richnow, Sabine Kleinsteuber, Marcell NikolauszAbstract:The effects of hydraulic retention time (HRT) reduction at constant high Organic Loading Rate on the activity of hydrogen-producing bacteria and methanogens were investigated in reactors digesting thin stillage. Stable isotope fingerprinting was additionally applied to assess methanogenic pathways. Based on hydA gene transcripts, Clostridiales was the most active hydrogen-producing order in continuous stirred tank reactor (CSTR), fixed-bed reactor (FBR) and anaerobic sequencing batch reactor (ASBR), but shorter HRT stimulated the activity of Spirochaetales. Further decreasing HRT diminished Spirochaetales activity in systems with biomass retention. Based on mcrA gene transcripts, Methanoculleus and Methanosarcina were the predominantly active in CSTR and ASBR, whereas Methanosaeta and Methanospirillum activity was more significant in stably performing FBR. Isotope values indicated the predominance of aceticlastic pathway in FBR. Interestingly, an increased activity of Methanosaeta was observed during shortening HRT in CSTR and ASBR despite high Organic acids concentrations, what was supported by stable isotope data.
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improved monitoring of semi continuous anaerobic digestion of sugarcane waste effects of increasing Organic Loading Rate on methanogenic community dynamics
International Journal of Molecular Sciences, 2015Co-Authors: Athaydes Francisco Leite, Leandro Janke, Zuopeng Lv, Hauke Harms, Hanshermann Richnow, Marcell NikolauszAbstract:The anaerobic digestion of filter cake and its co-digestion with bagasse, and the effect of gradual increase of the Organic Loading Rate (OLR) from start-up to overload were investigated. Understanding the influence of environmental and technical parameters on the development of particular methanogenic pathway in the biogas process was an important aim for the prediction and prevention of process failure. The rapid accumulation of volatile Organic acids at high OLR of 3.0 to 4.0 gvs·L−1·day−1 indicated strong process inhibition. Methanogenic community dynamics of the reactors was monitored by stable isotope composition of biogas and molecular biological analysis. A potential shift toward the aceticlastic methanogenesis was observed along with the OLR increase under stable reactor operating conditions. Reactor overLoading and process failure were indicated by the tendency to return to a predominance of hydrogenotrophic methanogenesis with rising abundances of the orders Methanobacteriales and Methanomicrobiales and drop of the genus Methanosarcina abundance.
Menglu Li - One of the best experts on this subject based on the ideXlab platform.
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volatile fatty acids production from food waste effects of ph temperature and Organic Loading Rate
Bioresource Technology, 2013Co-Authors: Jianguo Jiang, Yujing Zhang, Kaimin Li, Quan Wang, Changxiu Gong, Menglu LiAbstract:Abstract The effects of pH, temperature, and Organic Loading Rate (OLR) on the acidogenesis of food waste have been determined. The present study investigated their effects on soluble chemical oxygen demand (SCOD), volatile fatty acids (VFAs), volatile solids (VS), and ammonia nitrogen ( NH 4 + – N ). Both the concentration and yield of VFAs were highest at pH 6.0, acetate and butyRate accounted for 77% of total VFAs. VFAs concentration and the VFA/SCOD ratio were highest, and VS levels were lowest, at 45 °C, but the differences compared to the values at 35 °C were slight. The concentrations of VFAs, SCOD, and NH 4 + – N increased as OLR increased, whereas the yield of VFAs decreased from 0.504 at 5 g/L d to 0.306 at 16 g/L d. Acetate and butyRate accounted for 60% of total VFAs. The percentage of acetate and valeRate increased as OLR increased, whereas a high OLR produced a lower percentage of propionate and butyRate.
Wen Wang - One of the best experts on this subject based on the ideXlab platform.
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effect of Organic Loading Rate on anaerobic digestion of food waste under mesophilic and thermophilic conditions
Energy & Fuels, 2017Co-Authors: Wen Wang, Naveed Anwar, Ruihong ZhangAbstract:This study investigated the effect of Organic Loading Rate (OLR) on anaerobic digestion (AD) of food waste under mesophilic and thermophilic conditions. Results showed that the performance of the AD system was distinctly influenced by temperature and OLR in terms of biogas production, intermediate metabolism, and degradation performance. The optimal OLR under thermophilic condition was 2.5 g of volatile solids (VS)/L/day with methane yield (MY) of 541 mL/g of VSadded. In addition, the optimal OLR under mesophilic condition was 1.5 g of VS/L/day with a MY of 371 mL/g of VSadded. At the same OLR, the MY under thermophilic condition was 33–49% higher than that under mesophilic condition. Under thermophilic condition, steady methane production and degradation efficiency were achieved with considerably high OLR of 7.5 g of VS/L/day. Under mesophilic condition, stability was obtained only when the OLR was controlled below 2.5 g of VS/L/day. Results also revealed that food waste is a highly desirable substRate w...
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anaerobic treatment of cassava stillage for hydrogen and methane production in continuously stirred tank reactor cstr under high Organic Loading Rate olr
International Journal of Hydrogen Energy, 2010Co-Authors: Wen Wang, Qi Zhou, Hojae ShimAbstract:Abstract Anaerobic hydrogen and methane production from cassava stillage in continuously stirred tank reactor (CSTR) were investigated in this study. Results showed that the heat-pretreatment of inoculum did not enhance hydrogen yield compared to raw inoculum under mesophilic condition after continuous operation. However, the hydrogen yield increased from about 14 ml H 2 /gVS under mesophilic condition to 69.6 ml H 2 /gVS under thermophilic condition due to the decrease of propionate concentration and inhibition of homoacetogens. Therefore, temperature was demonstRated to be more important than pretreatment of inoculum to enhance the hydrogen production. Under high Organic Loading Rate (OLR) (>10 gVS/(L·d)), the two-phase thermophilic CSTR for hydrogen and methane production was stable with hydrogen and methane yields of 56.6 mlH 2 /gVS and 249 mlCH 4 /gVS. The one-phase thermophilic CSTR for methane production failed due to the accumulation of both acetate and propionate, leading to the pH lower than 6. Instead of propionate alone, the accumulations of both acetate and propionate were found to be related to the breakdown of methane reactor.