Showing papers on "Hydraulic retention time published in 2006"
TL;DR: The rate of soluble chemical oxygen demand (sCOD) removal correlated with digestion time according to the first-order kinetic model developed by Grau et al.
346 citations
TL;DR: A UASFF bioreactor with tubular flow behavior was developed in order to shorten the start-up period at low hydraulic retention time (HRT) for palm oil mill effluent (POME) treatment.
303 citations
TL;DR: According to denatured‐gradient‐gel‐electrophoresis analysis, operations at a progressively decreasing HRT resulted in a decrease in bacterial population diversity, and the culture with the best H2 production performance was eventually dominated by a presumably excellent H2‐producing bacterial species identified as Clostridium pasteurianum.
Abstract: A novel continuously stirred anaerobic bioreactor (CSABR) seeded with silicone-immobilized sludge was developed for high-rate fermentative H2 production using sucrose as the limiting substrate. The CSABR system was operated at a hydraulic retention time (HRT) of 0.5-6 h and an influent sucrose concentration of 10-40 g COD/L. With a high feeding sucrose concentration (i.e., 30-40 g COD/L) and a short HRT (0.5 h), the CSABR reactor produced H2 more efficiently with the highest volumetric rate (VH2) of 15 L/h/L (i.e., 14.7 mol/d/L) and an optimal yield of ca. 3.5 mol H2/mol sucrose. The maximum VH2 value obtained from this work is much higher than any other VH2 values ever documented. Formation of self-flocculated granular sludge occurred during operation at a short HRT. The granule formation is thought to play a pivotal role in the dramatic enhancement of H2 production rate, because it led to more efficient biomass retention. A high biomass concentration of up to 35.4 g VSS/L was achieved even though the reactor was operated at an extremely low HRT (i.e., 0.5 h). In addition to gaining high biomass concentrations, formation of granular sludge also triggered a transition in bacterial community structure, resulting in a nearly twofold increase in the specific H2 production rate. According to denatured-gradient-gel-electrophoresis analysis, operations at a progressively decreasing HRT resulted in a decrease in bacterial population diversity. The culture with the best H2 production performance (at HRT = 0.5 h and sucrose concentration = 30 g COD/L) was eventually dominated by a presumably excellent H2-producing bacterial species identified as Clostridium pasteurianum.
272 citations
TL;DR: An extended cost-benefit calculation shows that the highest overall benefit of the process is achieved at an OLR that is lower and a hydraulic retention time (HRT) that is longer than those values of OLR and HRT, at which the highest biogas production is achieved.
247 citations
TL;DR: In this paper, the use of B350M and B350 group microorganisms immobilized on carriers in a pair of Biological Aerated Filter (BAF) reactors to pre-treat oil field wastewater before desalination was investigated.
242 citations
TL;DR: The azo dye AR-88 was transformed to non-aromatic metabolic intermediates after treatment in sequential anoxic–aerobic bioreactor, and the UV–visible spectrophotometry, TLC and NMR analyses confirmed the biotransformation of parent dye into unrelated non-Aromatic compounds.
232 citations
TL;DR: In this article, a batch and continuous reactors inoculated with white-rot fungi were operated in order to study decolorization of textile dyes, including Reactive Blue 4 (a blue anthraquinone dye) and Reactive Red 2 (a red azo dye).
187 citations
TL;DR: An innovative pilot-scale photo-bioreactor that used sunlight and flue gas was developed to increase production of Euglena gracilis and showed improved cell yield compared with the laboratory-scale reactor.
187 citations
TL;DR: Molecular weight analysis of the feed, reactor contents, effluent, and extracellular polymers using high pressure liquid chromatography showed that the membrane filtered out most of the high MW soluble organics, resulting in high COD removals.
Abstract: Three 3 L laboratory scale submerged anaerobic membrane bioreactors (SAMBRs) with in situ membrane cleaning due to the bubbling of recycled biogas underneath them were studied for their ability to treat dilute wastewaters. Both Mitsubishi Rayon hollow-fiber and Kubota flat sheet membranes made of polyethylene with a pore size of 0.4 μm were used in this study, and the effect of different substrates ( 460 mg∕L of glucose or synthetic) on chemical oxygen demand (COD) performance in the SAMBR was investigated. It was found that both membranes resulted in similar COD removals ( >90% soluble COD at a hydraulic retention time of 3 h ), but that the transmembrane pressure across the hollow fiber membranes was higher under similar conditions. Molecular weight analysis of the feed, reactor contents, effluent, and extracellular polymers using high pressure liquid chromatography showed that the membrane filtered out most of the high MW soluble organics, resulting in high COD removals. The experimental results from t...
185 citations
TL;DR: Based on 16S rDNA analysis, a total of 21 operational taxonomy units (OTUs) were found in the sludge, of which eight were related to the sequences in the GenBank with similarity of over 97%, and 13 were affiliated with the known thermophilic species.
185 citations
TL;DR: It is concluded that the increase of the hydrogen yield after transition from 8 h to 6 h HRT is caused by a washout of the propionate producing population during the 6 H HRT period.
TL;DR: Results indicate that the pilot-plant wetland system can achieve removal of 61% COD, 89% BOD, 81% SS, 35% TP, and 56% NH(3)-N.
TL;DR: In this article, a carrier-induced granular sludge bed (CIGSB) was investigated to investigate the effect of temperature on H 2 production performance, and it was found that H 2 was most efficient at 40 ∘ C, especially when it was operated at a low hydraulic retention time (HRT) of 0.5
TL;DR: In this article, the characteristics of membrane fouling in an A/O (anoxic/oxic) series membrane bioreactor and in a vertical submerged membrane Bioreactor (VSMBR) treating synthetic wastewater were compared under the same operating conditions.
TL;DR: In this article, an improved 500 m3 closed digester was constructed to evaluate the POME treatment efficiency for a comparison study with the open digester system, which demonstrated a remarkable performance of high COD removal efficiency (up to 97%) and satisfactory ratio of volatile fatty acids: alkalinity (VFA:Alk) between 0.1 and 0.3.
TL;DR: In this paper, an improved upward-flow anaerobic sludge blanket (UASB) reactor with a working volume 50 m 3 was used for continuous biological hydrogen production using wastewater from citric acid factory as raw materials.
TL;DR: In this paper, an approach that used an industrial filter cloth material instead of the conventional MF/UF membrane to build a membrane bioreactor (MBR) for wastewater treatment was introduced.
TL;DR: In this article, the authors showed that the hydrogen generating microflora was isolated from the cow dung based on pH adjustment (pH 5) coupled with heat treatment (2.h).
01 Jan 2006
TL;DR: The most important operational factors for successful wastewater treatment with microalgae are depth, turbulence and hydraulic retention time.
Abstract: Microalgae can be used for tertiary treatment of wastewater due to their capacity to assimilate nutrients. The pH increase which is mediated by the growing algae also induces phosphorus precipitation and ammonia strip ping to the air, and may in addition act disinfecting on the wastewater. Domestic wastewater is ideal for algal growth since it contains high concentrations of all necessary nutrients. The growth limiting factor is rather light, especially at higher latitudes. The most important operational factors for successful wastewater treatment with microalgae are depth, turbulence and hydraulic retention time.
TL;DR: In this paper, a draft tube fluidized bed reactor (DTFBR) containing immobilized cell particles was designed to produce H2 continuously, and a synthetic polymer (silicone gel; SC) was used as the primary material to immobilize acclimated anaerobic sludge for H2 production in DTFBR with a working volume of 8 L.
TL;DR: In this article, a combined system consisting of Internal Circulation (IC) anaerobic reactor and Sequencing Batch Reactor (SBR) was used to treat swine wastewater in order to establish a cost-efficient wastewater treatment system.
TL;DR: The result indicated that a combination anaerobic-aerobic treatment system was effective in removing organic matter from the high-strength pharmaceutical wastewater, and the biodegradability of the wastewater was studied.
Abstract: Anaerobic and aerobic treatment of high-strength pharmaceutical wastewater was evaluated in this study A batch test was performed to study the biodegradability of the wastewater, and the result indicated that a combination anaerobic-aerobic treatment system was effective in removing organic matter from the high-strength pharmaceutical wastewater Based on the batch test, a pilot-scale system composed of an anaerobic baffled reactor followed by a biofilm airlift suspension reactor was designed At a stable operational period, effluent chemical oxygen demand (COD) from the anaerobic baffled reactor ranged from 1,432 to 2,397 mg/L at a hydraulic retention time (HRT) of 125 day, and 979 to 1,749 mg/L at an HRT of 25 day, respectively, when influent COD ranged from 9,736 to 19,862 mg/L As a result, effluent COD of the biofilm airlift suspension reactor varied between 256 and 355 mg/L at HRTs of from 50 to 125 h The antibiotics ampicillin and aureomycin, with influent concentrations of 32 and 10 mg/L, respectively, could be partially degraded in the anaerobic baffled reactor: ampicillin and aureomycin removal efficiencies were 164 and 259% with an HRT of 125 day, and 421 and 313% with HRT of 25 day, respectively Although effective in COD removal, the biofilm airlift suspension reactor did not display significant antibiotic removal, and the removal efficiencies of the two antibiotics were less than 10%
TL;DR: It is demonstrated that Fenton's reagent can effectively degrade leachate organics and temperature gave a positive effect on organic removal.
TL;DR: It is suggested that SSF CWs are not sensitive to the type of organic matter in the influents, whether it is readily (like glucose) or slowly (like starch) biodegradable, for the removal of COD.
TL;DR: The objective of this work was to evaluate the production of hydrogen in a continuous system as a function of hydraulic retention time (HRT), and the intermediates accumulated and other parameters of pH, oxidation-reduction potential were quantified.
TL;DR: In this paper, the use of a crossflow membrane bioreactor (CF-MBR) in treating wastewater discharged by a petroleum refinery was investigated, and the results showed that a COD removal efficiency of more than 93% was obtained at both MLSS values.
TL;DR: In this paper, a base-enriched anaerobic mixed microflora was used for hydrogen fermentation from sucrose in a laboratory scale model completely stirred tank bioreactor operating at 35°C.
TL;DR: Changes in fermentation pattern during the treatment of organic wastes containing solid materials by thermophilic anaerobic microflora were investigated with respect to product formation and bacterial community structure during hydrogen production.
Abstract: Aims: Changes in fermentation pattern during the treatment of organic wastes containing solid materials by thermophilic anaerobic microflora were investigated with respect to product formation and bacterial community structure during hydrogen production.
Methods and Results: Anaerobic microflora enriched from sludge compost was cultivated using artificial garbage slurry in a continuous flow-stirred tank reactor. Product formation varied depending on pH and hydraulic retention time (HRT) applied. Community analysis by terminal restriction fragment length polymorphism and clone library analysis of polymerase chain reaction-amplified bacterial 16S rDNA indicated that difference in the fermentative product distribution could be caused by different populations of micro-organisms in the microflora.
Conclusion: Hydrogen fermentation with acetate/butyrate formation was optimized at <1·0 d HRT at pH 5·0 and 6·0. Thermoanaerobacterium thermosaccharolyticum was the dominant hydrogen-producing micro-organism. Conversely, unidentified organisms became dominant after 4·0 d HRT at pH 7·0 and 8·0, where relatively high-solubilization efficiency of solid materials was observed with no production of hydrogen.
Significance and Impact of the Study: This is the first report describing product formation in the fermentation of solid organic wastes by a mixed population of micro-organisms. Various fermentation patterns including hydrogen fermentation were characterized and evaluated from engineering and microbial aspects.
TL;DR: The membrane performance showed clearly better results with increasing the sludge retention time from 8 to 40 d, and the concentration of the colloidal and soluble polysaccharides of the liquid phase was identified as the predominant parameter causing membrane fouling.
TL;DR: The objective was to better control biofilm formation in order to reduce the time of colonization during the start-up phase of an anaerobic high-rate biofilm reactor, and optimal methanogenic activity and COD removal were restored.