Treatment of landfill leachate by immobilized microorganisms

This paper focuses on the outcome and the main performance of the immobilized microbial that treats landfill leachate. Based on the analysis of COD and ammonia-nitrogen of the influent and effluent, research was done on the high removal efficiency of COD and ammonium nitrogen by immobilized microbial. The leachate composition was analyzed qualitatively using GC-MS before and after being treated. Biological loading of efficient microbial flora on the carrier was measured by Kjeldahl’s method. Finally, the patterns of immobilized microbe were observed through scanning electron microscopy (SEM). The results showed that in immobilized microorganisms system, the efficiencies of COD and nitrogen were 98.3% and 99.9%, respectively. There was a great reduction of organic components in effluent. When the immobilized biomass on the carrier was 38 g·L?1 (H2O), the filamentous microorganism was highly developed. There was no inhibitory effect on the nitrobacteria and nitrococcus, when ammonia was over 200 mg·L?1 and NH3 over 150 mg·L?1. At a high organic loading, it still had good nitrification. This paper also compares the performance of immobilized microbial with free microbial under the same condition. The immobilized microbial technology demonstrated better than the latter in all aspects.     

Application of magnetic immobilized microorganisms

Magnetic calcium alginate yeast beads, made by incorporation of magnetite or colloidal magnetic liquid, Ferrofluidℳ, exhibited catalytic behavior similar to that of their nonmagnetic counterparts. The magnetic immobilized preparations’ shortterm performance, long-term operational stability, and capacity forin situ activation were unaffected by the inclusion of magnetic material. The magnetic quality of the alginate beads provides manipulatory advantages.     

Adsorption of heavy metal ions by immobilized phytic acid

Applied Biochemistry and Biotechnology - Phytic acid (myoinositol hexaphosphate) or its calcium salt, phytate, is an important plant constituent. It accounts for up to 85% of total phosphorus in...     

Denitrification and removal of heavy metals from waste water by immobilized microorganisms

Pseudomonas fluorescens, immobilized on soft polyvinyl chloride granules containing up to 35% softeners as carbon source, was used for simultaneous removal of nitrate and heavy metals. In typical continuous column operation, a 100 mg/L nitrate input solution was reduced to a 20 mg/L output at a feeding rate of 1500 mL/h, with a capacity of 14 kg/day/m³, and with an efficiency of 79%. In the same column, Pb(NO₃)₂ concentration was reduced from 1.0 to 0.05−0.1 mg/L and ZnSO₄ concentration was reduced from 10 to 5 mg/L.Pseudomonas aeruginosa immobilized on an O₂ plasma-treated melt blown polypropylene web was used for removing 95% of a 1.7 nCi PuCl₄ activity from a nuclear plant waste water in a batch operation.     

Studies on the application of microorganisms immobilized by radiation in the pharmaceutical industry

Immobilization of the bacteria A. simplex by-2-13 was obtained by irradiation polymerization with an electron beam and gamma-radiation at 0°C. Prednisone acetate (P. A.) was derived from cortisone acetate (C. A.) by 1,2-dehydrogenation, catalyzed by immobilized A. simplex by-2-13. The immobilized bacteria were used 10 times in succession with a transformation percentage ranging from 77 to 86% for electron beam radiation and 79 to 99% for gamma radiation. Dehydrogenation, was carried out at pH 7.2, 34°C, 180–200 r.p.m. for 24 hours. 3% (v/v) anhydrous alcohol was added to the system at onset. Scanning electron micrographs documented the structure of the immobilized bacteria. In this work, the effect of absorbable doses of radiation and the reaction time of non-immobilized bacteria on dehydrogenase activity were studied. The effect of pH, temperature and concentration of substrate were also studied.     

复合纤维素固定化脲酶对铜离子的吸附作用

脲酶对重金属离子极为敏感。由复合纤维素（CC）固定化脲酸对铜离子的吸附现象得出的结论是：脲酶吸附的Cu~(2+)总量与其活性没有定量关系，而是与固酶重量成比例。从而可以认为，重金属离子不是直接作用于脲酶活性部位使其中毒的，很可能是作用于脲酶大分子其他部位，使分子构象变形后导致脲酶失活的。由于CC固酶对Cu~(2+)有吸附作用，且又不污染系统，所以可用其除去食品、药物及水中的Cu~(2+)离子。     

Comparison of BOD optical fiber biosensors based on different microorganisms immobilized in ormosil matrixes

Fiber-optical microbial sensors for determination of biochemical oxygen demand (BOD) are described. Sensing films consisting of layers of an oxygen-sensitive fluorescent material and two different kinds of seawater microorganisms immobilized in poly(vinyl alcohol) sol–gel matrix were investigated. Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) perchlorate was used as the oxygen fluorescent quenching indicator. After preconditioning, the BOD biosensors could consistently perform well for up to one month. For films of domestic bacilli and films of sieved bacteria from seawater, the linear fluctuant coefficients (R ²) in the range of 4–200?mg/L were 0.9975 and 0.9783 when a glucose/glutamate BOD standard was applied. The relative error of standard deviations for the two microorganism-immobilized BOD sensing films were within 4%?and 2%?of the mean value, respectively. The effects of temperature, pH and sodium chloride concentration on the two microbial films were also studied. For low biochemical oxygen demand, a film of sieved bacteria from seawater had superior sensitivity and is expected to be developed further.     

Effect of curing time on immobilized Cs and Sr Isotopes leached from cement matrices

To assess the conditions for the safe disposal of radioactive wastes by encapsulation in cements, the effect of curing time on the leaching of radionuclides prior to the commencement of leaching experiments has been investigated. Leach tests were carried out on various cement matrices, using a modified IAEA method recommended by Hespe¹.     

Adsorption recovery of thorium(IV) by Myrica rubra tannin and larch tannin immobilized onto collagen fibres

Novel adsorbents which can concentrate Th(IV) in aqueous solution were prepared by immobilizingMyrica rubra tannin and larch tannin onto collagen fibre matrices. The adsorption capacities of the immobilized tannins to Th(IV) are related to temperature and pH value of the adsorption process. For example, when the initial concentration of Th(IV) was 116.0 mg·l^-1 and the immobilized tannin was 100 mg, the adsorption capacities of immobilized Myrica rubra tannin and larch tannin were 55.98 mg Th(IV)·g^-1 and 13.19 mg Th(IV)·g^-1, respectively at 303 K, and 73.67 mg Th(IV)·g^-1 and 18.19 mg Th(IV)·g^-1 at 323 K. It was also found that the higher adsorption capacity was obtained at higher pH value. The adsorption equilibrium data of the immobilized tannins for Th(IV) can be well fitted by the Langmuir model and the mechanism of the adsorption was found to be a chemical adsorption. In general, the adsorption capacity of immobilized Myrica rubra tannin to Th(IV) is significantly higher than that of immobilized larch tannin, probably due to the fact that the B ring of Myrica rubra tannin has a pyrogallol structure which has higher reaction activity with metal ions. The breakthrough point of the adsorption column of immobilized Myrica rubra tannin was at 33 bed volumes for the experimental system. The mass transfer coefficient of adsorption column determined by Adams-Bohart equation was 1.61·10^-4 l·mg^-1.min^-1. The adsorption column can be easily regenerated by 0.1 mol·l^-1 HNO₃ solution, showing outstanding ability of concentrating Th(IV). This revised version was published online in July 2006 with corrections to the Cover Date.     

Adsorption and catalytic conversion of hydrocarbons on nanosized gold particles immobilized on alumina

Gold and nickel particles immobilized on alumina were prepared by the metal vapor synthesis and anionic adsorption methods. The dispersion of metals was determined by X-ray diffraction and transmission electron microscopy. The activity of nanoparticles, tested in model catalytic reactions of CCl₄ addition to multiple bonds and allyl isomerization of allylbenzene, changes in a wide range (from 1 to 3000 (mole of product) (mole of Au)⁻¹ h⁻¹) and is parallel to the chromatographically measured heats of adsorption of the corresponding unsaturated substrates. The heat of adsorption of unsaturated hydrocarbons can serve as a criterion for the efficiency of the gold-containing catalyst in olefin conversion. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2215–2218, October, 2005.     

Adsorption behaviour of cadmium on L-methionine immobilized on controlled pore glass

The adsorption behaviour of Cd onto the relative non-polar L-methionine was studied. To this end, L-met was immobilized on controlled pore glass (CPG), incorporated in a microcolumn and inserted in a flow injection system for Cd preconcentration from aqueous solutions. Binding constant of the system was calculated and it turned to be of 1.99, with sites capacity of n = 3.12. The ratio of Cd moles bound to L-met moles was calculated and it was 0.03:1 at pH 9.0. On-line breakthrough curves were used to study the effect of pH, analyte concentration and influent flow rate on Cd retention. A complementary pH study was added with a titration curve. Transient peak areas revealed that Cd stripping from the column occurred instantaneously. The system achieves an enrichment factor of 130, reaching a detection limit of 0.63 ng L^{− 1} when 10 mL of the solution were passed through the column. The method was successfully applied to Cd determination in the standard reference material (SRM), QC METAL LL2 metals in natural water, as a validation study.     

钽掺杂六方相氧化钨对Sr2+的吸附:Zeta电位的测量及吸附机理的研究

研究Ta掺杂六方相氧化钨(hex-WO₃)材料在吸附Sr²⁺过程中其表面zeta电位的变化情况,并进一步探讨了吸附过程的热力学及吸附机理。结果表明：(1)在实验pH值范围内,Ta掺杂hex-WO₃悬浮液的zeta电位值随溶液中电解质的价态增大而增大;(2)且zeta电位随体系中离子强度的增加而增大;(3) Ta掺杂hex-WO₃对Sr²⁺的吸附容量随着温度降低而增大,随着离子强度的增加而减少;(4)吸附过程的吸附焓为－47 kJ·mol^-1,且Sr²⁺离子与材料表面之间主要为化学相互作用;(5) Ta掺杂hex-WO₃对Sr²⁺吸附过程主要为材料表面吸附及材料孔道内离子交换共同作用。     

Sorption of platinum on immobilized microorganisms for its on-line preconcentration and chemiluminescent determination in water samples

Fungi of the type Aspergillus sp. were immobilized on a cellulosic resin and used as a biosorbent for the on-line preconcentration and separation of Pt(IV) ions prior to their chemiluminescent determination via flow injection analysis. Biosorption and elution conditions were optimized, and the results compared to biosorbents based on the use of Chlorella vulgaris algae and Saccharomyces cerevisiae yeast in terms of preconcentration and selective retention of Pt(IV). The immobilized fungi presented here have a high potential for use in platinum biosorption. The procedure exhibits the currently lowest limit of detection (0.02 ng mL^?1 of Pt) and very high selectivity. The procedure was applied to the determination of Pt(IV) in river water, road run-off, and wastewater samples.

Adsorption of direct black-38 azo dye on p-tert-butylcalix[6]arene immobilized material

The present study demonstrates the adsorption of the direct black-38 (DB-38) azo dye on potential and newly synthesized p-tert-butylcalix[6]arene based silica resin (4). Resin 4 was synthesized via the modification of pure silica 1 as 2 followed by the immobilization of p-tert-butylcalix[6]arene (3) onto modified silica (2). It was characterized by using different analytical techniques such as FT-IR, scanning electron microscopy (SEM) and thermo gravimetric analysis (TGA). The effect of adsorbent dosage, pH and the electrolyte effect on the removal of the DB-38 azo dye were evaluated through batch wise adsorption experiments. Maximum adsorption of 91% was achieved at pH 9.0. The textile wastewater samples were used to ensure the field applicability of the newly synthesized adsorbent 4 for the treatment of dye contaminated effluents. All results regarding the removal of the DB-38 azo dye from the aqueous environment prop up resin 4 as an effective adsorbent and it was found that resin 4 has high adsorption efficiency toward the DB-38 azo dye at a wide range of pH as compared to 1 and 2.     

Adsorption kinetic, isotherm and thermodynamic studies of Sr2+ onto hexagonal tungsten oxide

Hexagonal tungsten oxide (hex-WO₃) with exchangeable sodium and ammonium cations located in hexagonal channel was synthesized by a facile hydrothermal treatment of sodium tungstate dihydrate in concentrated HCl solution in the presence of ammonium sulfate. An attempt was made to assess the potential of hex-WO₃ for the adsorption of Sr²⁺ ions from acidic radioactive waste solutions. Adsorption of Sr²⁺ reached equilibrium very quickly in 2 h in acidic aqueous solution. Maximum removal of Sr²⁺ ions occurred at pH 4. Equilibrium studies showed that the extent of Sr²⁺ ions uptake by hex-WO₃ was better described by the Freundlich isotherm in comparison with the Langmuir model. The thermodynamic parameters showed that the adsorption of Sr²⁺ ions onto hex-WO₃ was spontaneous and exothermic under the studied conditions.     

Hydrogen production by photosynthetic microorganisms

Applied Biochemistry and Biotechnology - Hydrogen is a clean energy alternative to the fossil fuels, the main source of greenhouse gas emissions. We developed a stable system for the conversion of...     

Biotransformation of daidzein ditiglate by microorganisms

Biotransformation of the daidzein ditiglate (2) by fungi, Aspergillus niger and Glomerella cingulata was investigated. Compound 2 was transformed to daidzein (1) by A. niger and G. cingulata. This suggested that compound 2 was converted to compound 1 by hydrolysis at both of the C-7 and C-4' positions.     

Adsorption properties of manganese oxides prepared in aqueous-ethanol medium toward Sr(II) ions

Journal of Radioanalytical and Nuclear Chemistry - In this study, nanostructured manganese oxides were synthesized using sol–gel method by reduction of KMnO4 with ethyl alcohol. Firstly, the...     

l-DOPA production by immobilized tyrosinase

The production of l-DOPA using l-tyrosine as substrate, the enzyme tyrosinase (EC 1.14.18.1) as biocatalyst, and l-ascorbate as reducing agent for the o-quinones produced by the enzymatic oxidation of the substrates was studied. Tyrosinase immobilization was investigated on different supports and chemical agents: chitin flakes activated with hexamethylenediamine and glutaraldehyde as crosslinking agent, chitosan gel beads, chitosan gel beads in the presence of glutaraldehyde, chitosan gel beads in the presence of polyvinyl pyrrolidone, and chitosan flakes using glutaraldehyde as crosslinking agent. The last support was considered the best using as performance indexes the following set of immobilization parameters: efficiency (90.52%), yield (11.65%), retention (12.87%), and instability factor (0.00). The conditions of immobilization on chitosan flakes were optimized using a two-level full factorial experimental design. The independent variables were enzyme-support contact time (t), glutaraldehyde concentration (G), and the amount of enzyme units initially offered (U _C). The response variable was the total units of enzymatic activity shown by the immobilized enzyme (U _IMO). The optimal conditions were t=24 h, G=2% (v/v), and U _C=163.7 U. Under these conditions the total units of enzymatic activity shown by the immobilized enzyme (U _IMO) was 23.3 U and the rate of l-DOPA production rate was 53.97 mg/(L·h).     

FTIR Studies on NO Adsorption on [Co+Mg(Sr)]/ZSM-5

IntroductionThe FTIR spectroscopy of NO adsorption on[Co +Mg(Sr) ]/ZSM- 5 has not been fullyelucidated yet.Previous researchers working onNO adsorption over Co/ZSM- 5 stated that thebands at 1 81 0 and 1 890 cm-1are due to dinitrosylspecies adsorbed on Co2 +[1] ,while the band at193 5 cm-1is attributable to mononitrosyl species.Aband near1 85 8cm-1(w) may be attributable tothe species of Co3O4 —NO[2 ] .Further,Zhu etal.[2 ]reported the bands at1 81 3 ,1 896 and1 93 9cm-1assigned to …