Effects of slight variations in nutrient loadings on pore plugging in soil columns

The high nutrient concentrations that would exist near the nutrient injection well during the application of cometabolicin situ bioremediation may lead to the development of significant quantities of biomass at this point in the subsurface. This biomass can decrease the porosity of the soil to such an extent that nutrient injection is no longer possible. In this work, experiments were conducted using a porous media biofilm reactor, operated under constant substrate loading conditions, such that the pressure drop across the reactor was allowed to increase to maintain a constant volumetric flow rate through the reactor. Results suggest that biomass production, and hence biofilm thickness, near the injection feed port is highly sensitive to substrate loading. In addition, these variations in biofilm thickness produce dramatic differences in the pressure drop that is attained across the reactor. Use of the Kozeny-Carman equation can be used to predict that once a critical depth has been exceeded, the pressure drop across the bed will increase exponentially within biofilm depth. This result means that pressure is not a reliable indicator of the onset of pore plugging.     

Calorimetric Study of the Bioremediation of a Polluted Soil

The calorimetric cells of a Setaram BT 2.15 flux calorimeter have been modified, in order to measure the heat production associated with microbial growth, with a continuous flow of gas and liquid through the sample. Good conditions for the growth of the microorganisms present in a polluted soil were determined and the possibility of the bioremediation examined. It was shown that the biodegradation of hydrocarbons adsorbed for a long time in the soil is a very slow process difficult to study with calorimetry. On the contrary, sodium succinate and different C₁₄ hydrocarbons were easily biodegradated, producing a large quantity of heat.This revised version was published online in November 2005 with corrections to the Cover Date.     

Two-dimensional carbon cloth and three-dimensional carbon felt perform similarly to form bioanode fed with food waste

Two-dimensional carbon cloth and three-dimensional carbon felt were compared for their capacity to form bioanodes for food waste treatment. Wastewater was used as the dilution medium instead of a synthetic solution to be close to industrial conditions. In both cases, microbial cells were mainly wrapped around the fibers of the electrodes. The biofilms were around 80–120 μm thick with a 39.3% microbial volume ratio on carbon cloths. On carbon felt, the biofilms showed a lower microbial volume ratio of 16.3% on the upper layers but with a penetration depth of 200–800 μm. The biofilm patterns were different but they resulted in similar current density, around 3.5 A/m².When chemically rich media have to be implemented, 2D cloth offers a worthwhile solution that can equal 3D porous materials.     

Production of char from vacuum pyrolysis of South-African sugar cane bagasse and its characterization as activated carbon and biochar

The potential of vacuum pyrolysis to convert sugar cane bagasse into char materials for wastewater treatment and soil amendment is the focus of this research paper. Vacuum pyrolysis produces both bio-oil and char in similar quantities. Vacuum pyrolysis has the potential to produce high quality chars for wastewater treatment and soil amendment directly during the conversion process, with no further upgrading required. In the present study, chars with the required porous structure was obtained directly from the vacuum pyrolysis process, making it very efficient as adsorbent both in terms of methylene blue (MB) adsorption with a N₂-BET surface area of 418 m² g⁻¹. Further steam activation of the chars benefited the development of meso- and macroporosity, although this upgrading step was not essential to achieve the required performance of char as an MB adsorbent. The development of large pores during the vacuum pyrolysis favored physisorption of MB, rather than chemisorption. The chemical nature of the vacuum pyrolysis char resulted in a slightly acidic surface (pH 6.56). The biochar from vacuum pyrolysis can be considered as a highly beneficial soil amendment, as it would enhance soil nutrient and water holding capacity, due to its high cation exchange capacity (122 cmol_c kg⁻¹) and high surface area. It is also a good source of beneficial plant macro- and micronutrients and contains negligible levels of toxic elements.     

Calorimetric studies of solid wastes,sewage sludge,wastewaters and their effects on soil biodegradation processes

Calorimetric studies of solid wastes, sewage sludge, wastewaters and their environmental effects focus on three main research areas. The first research area involves determination of selected thermal and physical parameters characterizing the above substances, such as specific heat, thermal conductivity and others. The second area covers processes of total or gradual destruction of the examined substances at a fixed composition of the gaseous phase. The methods applied in this case enable to determine the heat of combustion or the calorific value of the analyzed material, as well as changes in the rate of heat production, measured by differential scanning calorimetry (DSC). The third area of calorimetric studies covers microbial calorimetry as a method for non-destructive monitoring of organic matter biodegradation in order to measure the kinetic and thermodynamic parameters of the investigated processes, i.e., wastewater treatment, composting and decomposition of organic soil matter, as well as to determine the stability of wastes. This paper describes, based on available literature data, the major directions of investigations, using different calorimetric methods, of solid wastes, sewage sludge and wastewaters and additionally their effects on soil microbial processes. The paper also presents the selected calorimetric studies and analyses the biodegradation kinetics of organic wastewaters and glucose decomposition in the presence of phosphogypsum in different soils.     

Taxonomic Identification and Use of Free and Entrapped Cells of a New <Emphasis Type="Italic">Mycobacterium</Emphasis> sp., Strain Spyr1 for Degradation of Polycyclic Aromatic Hydrocarbons (PAHs)

A polycyclic aromatic hydrocarbon (PAH)-degrading bacterial strain Spyr1 was isolated from Greek creosote polluted soil by an enrichment method using pyrene as sole carbon and energy source. Spyr1 was identified as Mycobacterium sp. based on 16S rDNA analysis and it was capable of degrading pyrene, fluoranthene, fluorene, anthracene, and acenaphthene. The effect of entrapment in glass beads and alginate/starch mixtures on the survival and pyrene degradation ability of Spyr1 cells in liquid suspensions and soil microcosms was tested and compared with that of freely suspended cells. In general, free cells showed higher degradation of pyrene and other PAH than immobilized cells. However, immobilized cells could better tolerate PAH and they maintained their viability and PAH degradation capability for at least 1 year after storage at 4 °C. Entrapped cells in glass beads exhibited better pyrene biodegradation performance than alginate/starch entrapped cells in liquid suspensions and could be used effectively for at least ten repeated cycles. Alginate/starch entrapped cells exhibited better yields than glass beads entrapped cells for removing pyrene as well as mixtures of PAH in soil microcosms.     

A microcalorimetric enzymatic method for trehalose determination in food

As trehalose is a glucose font and also an additive in food, a new reliable method for trehalose determination is proposed. The analytical method uses an isothermal microcalorimeter, directly relates the analyte concentration with the heat variation of the enzymatic decomposition of trehalose into two glucose molecules. The enzymatic reaction is performed inside the calorimeter in the presence of trehalase enzyme immobilized on amino activated glass beads. Through the calibration curve, the trehalose quantity in some food samples (mushrooms and honey) has been determined. The calorimetric procedure was compared to a previously identified methodology based on an amperometric biosensor.     

Comparative Study of Electrochemical Performance and Microbial Flora in Microbial Fuel Cells by Using Three Kinds of Substrates

This work aimed to investigate the distinct electrochemical performance and microbial flora of microbial fuel cells(MFCs)in relation to different single hazardous fed fuels.Three replicate MFCs were inoculated with the same microbial consortium from a coking wastewater treatment plants wherein ammonium chloride(ammoniiim chlo-ride-fed MFC,N-MFC),phenol(phenol-fed MFC,P-MFC)and potassium sulphide(potassium sulphide-fed MFC,S-MFC)were the sole substrates and main components of real coking wastewater.With initial concentrations of am-monium chloride,phenol and potassium sulphide of 0.75,0.60 and 0.55 g/L,the removal efficiencies reached 95.6%,90.6%and 99.9%,respectively,whereas the peak output power densities totalled 697,324 and 1215 mW/m^2.Micro-bial community analysis showed that the respective addition of substrate substantially altered the microbial community structure of anode biofllm,resulting in changes in relative abundance and emergence of new strains and further affecting the electrochemical properties of MFCs.The chemical oxygen demand(COD)removal efficiency of real coking wastewater,in which,the inoculum was the combined biomass from the three MFCs,reached 82.3%.     

Evaluation of bacterial detachment rates in porous media

The ability of published biomass detachment rate expressions to describe experimental data obtained from porous media reactors usingPseudomonas aeruginosa grown aerobically on glucose was evaluated. A first-order rate expression on attached biomass concentration best reflected effluent substrate concentration for combined data sets. Detachment rate coefficientk _d1 was dependent on initial substrate concentration. Simulation of porous media reactor experiments indicated that responses using higher influent substrate concentrations possessed greater sensitivity to variations ink _d1. Simulations of field bioremediation systems suggest the use of accurate biofilm development kinetics is important in the prediction of well bore biofouling.     

Potentiometric Biosensing of Penicillins Using a Flow-Through Reactor with Penicillinase or Penicillin Amidase Immobilized by Gamma-Irradiation

Abstract

Penicillinase and penicillin amidase were immobilized, with similar yield, by physical entrapment in porous beads of poly-2-hydroxyethyl methacrylate matrix formed by gamma-irradiation. Flow-injection analysis of penicillins was performed by using a column reactor filled with enzyme-loaded polymer beads and a wall-jet pH-metric micro-cell with a combined flat-membrane glass electrode as the sensing element. With both enzymes it was possible to have either a linear response dynamic range or a logarithmic one by appropriate selection of buffer capacity and flow rate of the carrier solution.     

Lithium adsorption properties of porous LiAl-layered double hydroxides synthesized using surfactants

Porous LiAl-layered double hydroxides (LiAl-LDHs) of [Li₂Al₄(OH)₁₂](CO₃)·4H₂O were hydrothermally synthesized in one-pot by mixing LiCl, AlCl₃, urea, and one surfactant each (sodium dodecyl sulfate (SDS), octadecyl amine (OA), and sodium lauryl sulfonate (SLS)) as soft templates. The LiAl-LDHs were granulated by crosslinked sodium alginate. The LiAl-LDHs were characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and porosity. Special attention was focused on the rise of Li⁺ adsorption capacity based on the porous morphology in synthetic and real salt lake brine. The adsorption capacity of granulated LiAl-LDHs-SLS reaches 8.48 mg/g in a solution containing 300 mg/L of Li⁺ at pH = 7 and 11.8 mg/g from Da Qaidam brine with 1.0 g/L of Li⁺. Lithium adsorption followed the Langmuir isotherm and pseudo-second-order kinetics. Temperature, solution pH, and other electrolytes had a minor effect on the adsorption performance of porous LiAl-LDHs. The structure of surfactants had a significant influence on the porosity of synthesized LiAl-LDHs, and thus on the adsorption capacity.     

On the microporous structure of glass beads

Summary Glass beads of controlled porosity are interesting packings for chromatography. They are used as molecular sieves and they can constitute the starting point for the production of packings with a chemically bonded phase. From the practical point of view it would be desirable to known the methods for obtaining porous glass beads of strictly defined structure. In this communication attention will be drawn to the occurrence of microporous structure in glass beads, which is an unfavourable phenomenon from the standpoint of chromatography. Moreover, a method allowing us to remove the microporosity will also be discussed.     

Method of Separating the Sensitive Volume of Calorimetric Cells in a Differential Titration Calorimeter

A scientific and technical solution of capillary calorimetric unit design is described based on a method of separating the sensitive volume of calorimetric cells with a heat-conducting bridge in a differential titration calorimeter. The design of the calorimetric cells as thin capillary tubes allowed to minimize the dimension of the heat-conducting bridges and to separate with high accuracy the sensitive volume of the calorimetric cells which is of 78.5 μl. Due to high calorimeter power sensitivity (10 nW) a modern level of requirements for measuring minimum specific heat of processes is provided. The adopted design of the calorimetric cells permits to possess the cells located horizontally and to simplify the solution of the problem of equalizing components concentration along the volume of the calorimetric cells. This revised version was published online in July 2006 with corrections to the Cover Date.     

A calorimetric unit for measurements of the thermal effects of reactions in solution

A calorimetric unit for measurements of the thermal effects of reactions in solution was created. The unit was designed following the classic scheme of a hermetic liquid calorimeter working under isoperibolic conditions, it had a thermometric sensitivity of 10⁻⁴ K and a calorimetric sensitivity of 10⁻² J. The accuracy of calorimeter operation was checked against the heats of solution of potassium chloride. The molar integral enthalpies of solution of glycine in water at 298 K were determined.     

The Effect of Biomass Immobilization Support Material and Bed Porosity on Hydrogen Production in an Upflow Anaerobic Packed-Bed Bioreactor

The aim of this study was to investigate the effect of the support material used for biomass attachment and bed porosity on the potential generation of hydrogen gas in an anaerobic bioreactor treating low-strength wastewater. For this purpose, an upflow anaerobic packed-bed (UAPB) reactor fed with sucrose-based synthetic wastewater was used. Three reactors with various support materials (expanded clay, vegetal coal, and low-density polyethylene) were operated for hydraulic retention time (HRT) of 0.5 and 2 h. Based on the results obtained, three further reactors were operated with low-density polyethylene as a material support using various bed porosities (91, 75, and 50 %) for an HRT of 0.5 h. The UAPB reactor was found to be a feasible technology for hydrogen production, reaching a maximum substrate-based hydrogen yield of 7 mol H₂ mol^?1 sucrose for an HRT of 0.5 h. The type of support material used did not affect hydrogen production or the microbial population inside the reactor. Increasing the bed porosity to 91 % provided a continuous and cyclic production of hydrogen, whereas the lower bed porosities resulted in a reduced time of hydrogen production due to biomass accumulation, which resulted in a decreasing working volume.     

Chip calorimetry for fast cooling and thin films: a review

Here we review on the thin-film chip calorimeter with controllable cooling as well as heating rates up to 10⁶ K·s⁻¹ developed in the last 5 years at the Institute of Physics, Rostock University. The calorimeter has been successfully used for fast thermal processing and simultaneous calorimetric measurements of many polymer samples, the physical properties of which are generally dependent strongly on their thermal history. Besides, owing to the very small addenda heat capacity, the calorimeter is very sensitive to study samples of only several tenths of nanograms. With differential alternating current (AC) design, the sensitivity of the calorimeter increased to a few tenths of pico-Joules per Kelvin. Therefore, it can be used to study glass transition of polymers confined in ultra-thin films down to several nanometers thickness. After the discussion of the strategy to realize fast cooling, we describe the static and dynamic thermal properties of the sensors used for the setup of the calorimeter. Finally, we present examples to show the performance of the calorimeter in different measurement modes.     

Size control and catalytic activity of highly dispersed Pd nanoparticles supported on porous glass beads

This paper presents a novel in situ method to prepare monodispersed palladium nanoparticles supported on porous glass beads with an egg-shell structure at room temperature. This method integrates two processes of ion exchange and reduction in one step just by changing the solvent from water to alcohol. The monodispersed Pd nanoparticles around 3.75 nm in diameter with a face-centered cubic structure have been successfully prepared. The adsorption capacity for palladium reached 55.00 ± 0.55 mg/g in ethanol, which was 26 times larger than that in water. These Pd nanoparticles supported on porous glass beads showed an excellent catalytic performance through the hydrogenation of cyclohexene. In addition, this in situ method was also successfully applied to prepare monodispersed silver and gold nanoparticles supported on porous glass beads. Overall, this facile method provided an alternative for preparing a supported nanoparticle catalyst in a green way.     

Surface modification of glass beads with poly(acrylic acid)

Non‐porous P₂ glass beads were etched with sodium hydroxide to increase the number of silanol groups that could be used to modify the surface. The etched glass beads were then functionalized with 3‐aminopropyltriethoxysilane (APS) and/or glycidoxypropyltrimethoxysilane (GPS). The surface of the glass beads were further modified with poly(acrylic acid) (PAA) by reacting the carboxyl groups on PAA with the amino groups of the pregrafted APS. The chemical modifications were characterized by FT‐IR spectroscopy, particle size analyzer and tensiometry for contact angle and porosity measurements. Five different molecular weight PAA polymers ranging from 2000 to 3,000,000 were grafted with less than expected increase of grafted PAA with molecular weight. The amount of APS and PAA on the surface was determined from thermogravimetric analysis and elemental analysis data. The surface properties of the surface modified glass beads were determined by measuring water and hexane penetration rate and contact angle. The surface morphology was examined by scanning electron microscopy. Copyright © 2006 John Wiley & Sons, Ltd.     

Rhamnolipid Production by <Emphasis Type="Italic">Pseudomonas Aeruginosa</Emphasis> GIM 32 Using Different Substrates Including Molasses Distillery Wastewater

A rhamnolipid production strain newly isolated from oil-contaminated soil was identified as Pseudomonas aeruginosa GIM32 by its morphology and 16S rDNA sequence analysis. The effect of carbon source and carbon to nitrogen (C/N) ratio on rhamnolipids production was investigated. Palm oil was favorable as a carbon source for rhamnolipid production. The maximum biomass and rhamnolipid concentration were 8.24 g/L and 30.4 g/L, respectively, with an optimization medium containing 50 g/L palm oil and 5 g/L sodium nitrate. Molasses distillery wastewater as an unconventional substrate for rhamnolipid production was investigated. It was found that 2.6 g/L of rhamnolipids was produced; this amount was higher than that of past reports using wastewater as a substrate. In addition, 44% of the chemical oxygen demand of wastewater was removed at the same time under the optimization condition. Eleven kinds of different molecular weight rhamnolipid homologues were identified in the rhamnolipids obtained from molasses distillery wastewater by P. aeruginosa GIM32 by LC–MS analysis.     

Axial development and radial non-uniformity of flow in packed columns

Flow inhomogeneity and axial development in low-pressure chromatographic columns have been studied by magnetic resonance imaging velocimetry. The columns studied included (a) an 11.7-mm I.D. column packed with either 50 microm diameter porous polyacrylamide, or 99 or 780 microm diameter impermeable polystyrene beads, and (b) a 5-mm I.D. column commercially packed with 10 microm polymeric beads. The packing methods included gravity settling, slurry packing, ultrasonication, and dry packing with vibration. The magnetic resonance method used averaged apparent fluid velocity over both column cross-sections and fluid displacements greater than one particle diameter and hence permits assessment of macroscopic flow non-uniformities. The results confirm that now non-uniformities induced by the conical distributor of the 11.7-mm I.D. column or the presence of voids at the column entrance relax on a length scale of the column radius. All of the 11.7-mm I.D. columns examined exhibit near wall channeling within a few particle diameters of the wall. The origins of this behavior are demonstrated by imaging of the radial dependence of the local porosity for a column packed with 780 microm beads. Columns packed with the 99-microm beads exhibit reduced flow in a region extending from ten to three-to-five particle diameters from the wall. This velocity reduction is consistent with a reduced porosity of 0.35 in this region as compared to approximately 0.43 in the bulk of the column. Ultrasonicated and dry-packed columns exhibit enhanced flow in a region located between approximately eight and 20 particle diameters from the wall. This enhancement maybe caused by packing density inhomogeneity and/or particle size segregation caused by vibration during the packing process. No significant non-uniformities on length scales of 20 microm or greater were observed in the commercially packed column packed with 10 microm particles.