CFD optimization of continuous stirred-tank (CSTR) reactor for biohydrogen production.

There has been little work on the optimal configuration of biohydrogen production reactors. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of gas-liquid flow in a laboratory-scale continuous stirred-tank reactor used for biohydrogen production. To evaluate the role of hydrodynamics in reactor design and optimize the reactor configuration, an optimized impeller design has been constructed and validated with CFD simulations of the normal and optimized impeller over a range of speeds and the numerical results were also validated by examination of residence time distribution.

Polychlorinated biphenyls in global air and surface soil: distributions, air-soil exchange, and fractionation effect.

Polychlorinated biphenyl (PCB) concentrations in air and soil, measured by various research groups from around the world, were compiled and analyzed. Data for air were available from most regions, particularly in Europe and Asia. The average air concentrations (pg/m(3)) for SigmaPCB at background sites were 70 (5.

Effect of temperature on intracellular phosphorus absorption and extra-cellular phosphorus removal in EBPR process.

This study investigated the temperature influence on intracellular absorption and extra-cellular phosphorus removal by extra-cellular polymeric substance (EPS) in enhanced biological phosphorus removal (EBPR) process. Three sequencing batch reactors (SBRs) were operated in anaerobic/aerobic sequence at 5.0, 15.

Dechlorane Plus in surficial water and sediment in a northeastern Chinese river.

Surface water and sediment samples concurrently collected in Songhua River in northeastern China from May to October 2006 were analyzed for Dechlorane Plus (DP), a chlorinated flame retardant. Samples were obtained from three main areas: SHR-Rul (rural area of Songhua River), SHR-Hrb (the section of the river within the city of Harbin), and Hrb (urban waters of Harbin). The majority of SHR-Rul water samples (85%) and SHR-Hrb water samples (73%) and 33% of urban water samples (Hrb) were below the detection limit.

Enhanced bio-hydrogen production by the combination of dark- and photo-fermentation in batch culture.

In this study, some key factors, for example, diluted ratio of effluents, the ratio of dark-photo bacteria, light intensity and light/dark cycle influencing hydrogen production by combining Clostridium butyricum and immobilized Rhodopseudomonas faecalis RLD-53 in batch culture, were investigated. Experimental results showed the photo-hydrogen yield decreased when increasing diluted ratio from 1:0.5 to 1:3, and it reached the maximum value of 4368 ml-H(2)/l-effluents at the ratio of 1:0.

Effect of carbon sources on sulfidogenic bacterial communities during the starting-up of acidogenic sulfate-reducing bioreactors.

The effect of different carbon sources on the starting-up duration of sulfidogenic bioreactor and corresponding bacterial communities were investigated. The bioreactor starting-up duration was closely dependent on the complexity and availability of the carbon sources. 16S rRNA gene diversity of climax bacterial communities developed in each bioreactor had an increasing tendency for the carbon resource of lactate, acetate/ethanol, glucose and molasses.

Statistical optimization of culture condition for enhanced hydrogen production by Thermoanaerobacterium thermosaccharolyticum W16.

The optimization of culture condition for enhanced hydrogen production by Thermoanaerobacterium thermosaccharolyticum W16 was conducted using statistical experimental design and analysis. Plackett-Burman design was first used to screen the most important variables influencing hydrogen production, and subsequently central composite design was adopted to investigate the optimum value of the selected factors for achieving maximum hydrogen yield. Experimental results showed that xylose, phosphate buffer, and yeast extract had significant influence on hydrogen production and the maximum hydrogen yield of 2.

[Analysis of dynamic characteristics for fermentative hydrogen-producing bacteria community and hydrogen producing capability in CSTR].

The start into the types of fermentation was carried out by pH adjustment from 4.2 to 6.0 in CSTR system.

Effect of sulfate absence and nitrate addition on bacterial community in a sulfidogenic bioreactor.

The characteristics and behavior of sulfate-reducing bacteria (SRB), methane-producing bacteria (MPB) and denitrifying bacteria (DB) were investigated by polymerase chain reaction (PCR) based methods under the transitory sulfate absence or nitrate addition conditions in a sulfidogenic continuously stirred tank reactor. The bioreactor started-up feeding with 4000 mg l(-1) COD (lactate) and 2000 mg l(-1) sulfate (SO(4)(2-)). The sulfate removal efficiency reached 3.

Back propagation neural network (BPNN) prediction model and control strategies of methanogen phase reactor treating traditional Chinese medicine wastewater (TCMW).

Based on the prototype experiment of treating herb wastewater by Up flow Anaerobic Sludge Bed and Anaerobic Filter reactor (UASBAF), an artificial neural network (ANN) model which adopts a back propagation algorithm with momentum and adaptive learning rate was established. And the effect of each parameter to the performance of the reactor was compared, using the method of partitioning connection weights (PCW). The result is pH values>influent of chemical oxygen demand (COD)>hydraulic retention time (HRT)>alkalinity.

Improving phosphate buffer-free cathode performance of microbial fuel cell based on biological nitrification.

To reduce the amount of phosphate buffer currently used in Microbial Fuel Cell's (MFC's), we investigated the role of biological nitrification at the cathode in the absence of phosphate buffer. The addition of a nitrifying mixed consortia (NMC) to the cathode compartment and increasing ammonium concentration in the catholyte resulted in an increase of cell voltage from 0.3 V to 0.

[Effect of sludge bulking on membrane fouling of MBR under low temperature].

The performance and membrane fouling of submerged membrane bioreactor were studied in the case of active sludge bulking under low temperature. The factors contributing to membrane fouling were discussed from the microorganism aspect. The results showed that COD removal efficiencies of supernatant and permeate were 85% and 92% respectively and filamentous sludge bulking had little impact on them.

[Characterization of phosphate-accumulating organisms in starting-up EBPR by FISH analysis].

Enhanced biological phosphorus removal (EBPR) process was operated in a laboratory-scale sequencing batch reactor (SBR) for one-month fed with acetate as the carbon source. The characteristic and the microbial population structure and space distribution dynamics of phosphate-accumulating organisms (PAOs) of start-up period were analyzed by fluorescent in situ hybridization (FISH). The relationship between enrichment of PAOs and phosphorus removal was discussed.

Hydrogen production by immobilized R. faecalis RLD-53 using soluble metabolites from ethanol fermentation bacteria E. harbinense B49.

In order to increase the hydrogen yield from glucose, hydrogen production by immobilized Rhodopseudomonas faecalis RLD-53 using soluble metabolites from ethanol fermentation bacteria Ethanoligenens harbinense B49 was investigated. The soluble metabolites from dark-fermentation mainly were ethanol and acetate, which could be further utilized for photo-hydrogen production. Hydrogen production by B49 was noticeably affected by the glucose and phosphate buffer concentration.

[Effect of temperature on performance of microbial fuel cell using beer wastewater].

The effects of temperature on performance and biological community structure were investigated in air-cathode microbial fuel cells (MFCs) using beer wastewater amended with 50 mmol/L phosphate buffer solution (PBS). The maximum power density decreased from 483 mW/m2 to 435 mW/m2 when the temperature varied from 30 degrees C to 20 degrees C, meanwhile just a little decreasing on coulombic efficiency and the COD removal rate were observed. Decreasing of temperature resulted in effects both on cathode potential and anode potential, but cathode potential behaved much more sensitive to temperature.

Behavior and characteristics of dissolved organic matter during column studies of soil aquifer treatment.

Soil column experiments were performed to investigate the behavior and characteristics of dissolved organic matter (DOM) during soil aquifer treatment (SAT), and to differentiate among the mechanisms responsible for the changes in the structural and functional properties of DOM during SAT. To determine the biological transformation of DOM, biodegradability tests using a biodegradation-column system were conducted. DOM was fractionated using XAD resins into 5 fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI).

Enhanced photo-H2 production of R. faecalis RLD-53 by separation of CO2 from reaction system.

The effect of different gases, CO(2) concentration, and separation of CO(2) from reaction system on photo-fermentation H(2) production was investigated by batch culture in this study. Experimental results showed that different gases (Ar,N(2),CO(2), and air) as gas phase have obviously affected on photo-H(2) production and a high concentration of CO(2) can inhibit the growth and H(2) evolution of Rhodopseudomonas faecalis RLD-53. When CO(2) concentration at 5%, cell increased most rapidly the specific growth rate of 0.

[Capability and bacteria community analysis of an anaerobic baffled reactor treating soybean wastewater].

Capability and process characteristic of anaerobic baffled reactor (ABR) treating soybean wastewater were investigated in a 4-compartment ABR with an effective volume of 28 L. During an operation period of 100 days, the organic loading rate (OLR) increased by stages and its influence on the chemical oxygen demand (COD) removal efficiency was researched. The bacteria community structures in anaerobic activated sludge from different stages were also investigated by single-strand conformation polymorphism (SSCP) with the eubacterium universal primers SRV3-2P and BSF8/20, while the microbial genetic distance being analyzed by UPGMA communities clustering method.

Optimization of culture conditions for hydrogen production by Ethanoligenens harbinense B49 using response surface methodology.

The design of an optimum and cost-efficient medium for high-level production of hydrogen by Ethanoligenens harbinense B49 was attempted by using response surface methodology (RSM). Based on the Plackett-Burman design, Fe(2+) and Mg(2+) were selected as the most critical nutrient salts. Subsequently, the optimum combination of the selected factors and the sole carbon source glucose were investigated by the Box-Behnken design.

[Novel phosphorus and nitrogen removal process for municipal sewage treatment: performance evaluation and design optimization].

A novel modified A2/O process (MMAO) was developed for nitrogen and phosphorus removal of municipal sewage. Bench-scale study was conducted to evaluate the performance of the MMAO process treating practical municipal sewage at normal temperature. Activated sludge model (ASM2D) was used to simulate the MMAO process and optimize its design and operation.

[Induced apoptosis and mechanism of endosulfan in mouse germ cells].

Endosulfan which is going to be included as POPs in effect of organism have become the focus of international concern. To explore endosulfan on apoptosis of spermatogenic cells and mechanisms, doses of 7.0, 3.

Hydrogen production with R. faecalis RLD-53 isolated from freshwater pond sludge.

The Rhodopseudomonas faecalis strain RLD-53 was isolated from freshwater pond sludge and was demonstrated it could produce hydrogen. This study to investigate their ability of hydrogen production under some conditions in batch culture experiments. At pH 7.

[Anaerobic biodegradation pathway of the main ingredient of traditional Chinese medicine wastewater].

A laboratory-scale experiment was done. And the baicalin anaerobic biodegradation curve and pathway were discussed by analyzing the results of GC-MS. After analogue of status's trend and analysis of its regression, the biodegradation kinetic equation of baicalin was obtained.

[Flocculent genomic clone and flocculating mechanism analysis].

One strain, named as Bacillus sp. F2, of which flocculent ability can reach 84%, was separated. Flocculent genomic library was constructed.