Ionic Competition Effects in a Continuous Uranium Biosorptive Recovery Process

Immobilized Rhizopus arrhizus biomass was studied in a continuous sorption and desorption mode in order to identify factors that affect the long term uranium biosorptive uptake capacity performance of the immobilized biomass. Laboratory-scale continuous operation pilot plant experiments were performed using synthetic uranyl nitrate and industrial uranium mine leachate solutions. Analysis of the liquid solutions indicated that the immobilized Rhizopus arrhizus biomass successfully recovered all of the uranium from the dilute (less than 500 mg U dm⁻³) solutions. All uranium can subsequently be eluted, yielding highly concentrated uranium eluates. The immobilized Rhizopus arrhizus biomass maintained its uranium biosorptive uptake capacity over 12 successive sorption–elution cycles when synthetic uranyl nitrate solutions were used. However, when used with mine leachate solutions, an 18% reduction in the uranium biosorptive uptake capacity occurred within the first four adsorption–elution cycles. Spectral analysis indicated that, during continuous use and reuse, the immobilized biomass retained its structural integrity. EDAX, scanning and transmission electron microscopic techniques employed on the microbial biomass suggested that the presence of aluminium interferes with the uranium biosorption process. Spectral analysis also indicated that the presence of silicon enhances the negative effect of the presence of aluminium on the uranium biosorptive uptake capacity of the immobilized Rhizopus arrhizus biomass particles. © 1997 SCI     

Preparation of macroreticular chelating resins containing dihydroxyphosphino and/or phosphono groups and their adsorption ability for uranium

The macroreticular chelating resins (RSP, RSPO, RCSP, and RCSPO) containing dihydroxy-phosphino and/or phosphono groups were prepared and their adsorption capacity for UO₂²⁺ and the recovery of uranium from sea water were investigated. RSP and RCSP were prepared by phosphorylation of macroreticular styrene–divinylbenzene copolymer beads and the chloromethylated copolymer beads, respectively. RSPO and RCSPO were prepared by oxidation of RSP and RCSP, respectively. The order of recovery of uranium from sea water with these four resins is as follows: RCSPO ? RCSP > RSPO > RSP. The adsorption of uranium in sea water was not only affected by the chemical structure, but also by physical structure of the resins. Uranium absorbed on the resins was eluted with 0.25 ～ 1 mol·dm^?3 Na₂CO₃ or NaHCO₃ solution by batch and column methods. The average recovery ratios of uranium from sea water with Na-form and H-form RCSP on 10 recycles were 84.9% and 90.5%, respectively, when 20 dm³ of sea water was passed through the column (resin 4 cm³, 10 mm ? × 50 mm) at the space velocity of 60 h^?1. RCSP has a high physical stability and resistance against acid and alkali solution.     

Vegetable composts for sea water uranium extraction

Composting wood or crop residues by the addition of tanneries sludge as nitrogen supplement yields products having lower polysaccharides and protein content, but higher relative concentration of lignin material than the starting mixture. When used as sea water uranium adsorbents, the compost products exhibit higher uranium uptake (3.0–100 μg g^?1) than parent ligno-cellulosic materials (0.3–9 μg g^?1), thus achieving over 10⁴-fold uranium concentration relative to sea water. An additional distinguishing feature is the strong pH effect observed on uptake by products. The results are consistent with the expected change of parent lignin to lignin-humus in the compost product.     

螯合纤维对海水中铀的吸脱附性能研究

采用偕胺肟基螯合纤维对海水中的铀进行吸附,讨论了纤维制备条件对纤维吸附铀量的影响。结果表明:随着螯合纤维偕胺肟化时间的延长,纤维的吸附铀量增大;含偕胺肟基团的纤维经过碱水解后,纤维吸附铀量增大,适宜的碱处理时间为24 h;螯合纤维对铀的吸附量随着吸附时间的延长而逐渐增多,吸附时间超过48 h达到吸附饱和态,其饱和吸附量为2.6 mg/g。     

微生物固定化网状聚氨酯载体的研制

介绍微生物固定化网状聚氨酯泡沫塑料载体的制备工艺,着重讨论多元醇种类和用量、发泡剂用量和发泡工艺对泡沫孔径和密度等的影响,并对这种新型载体和陶粒载体的应用实验进行比较。结果表明,在污水处理中,网状聚氨酯泡沫塑料附着的菌量多,是较好的新型微生物固定化载体。     

Preparation of fibrous adsorbents containing amidoxime groups by radiation-induced grafting and application to uranium recovery from sea water

Polypropylene fibers and polyethylene hollow fibers were used as trunk polymers and were irradiated by electron beams with a dose of 200 kGy under N₂ atmosphere. Grafting of acrylonitrile to those irradiated fibers was carried out at 40°C for different periods of time. The degree of grafting was determined as a function of time. The fibrous adsorbents containing amidoxime groups were prepared by the reaction of acrylonitrile-grafted polymers with 3% hydroxylamine in a methanol–water mixture (1 : 1). Distribution of copper ions complexed with amidoxime groups at various adsorption times was obtained by electron-probe X-ray microanalysis. The amidoxime groups are homogeneously distributed in the cross section of fibrous adsorbents. The fibrous adsorbents based upon polypropylene fiber of 40 μm showed a remarkable kinetic behavior for Cu²⁺. Even after 15 min, the adsorption capacity was 2.32 mmol Cu²⁺ per gram of fiber. Also, the functionalization with hydroxylamine was carried out at different conditions to compare the adsorption characteristics of the resultant adsorbents. Despite having superficially different properties (elemental microanalysis, ion-exchange capacities, adsorption capacity for UO), the polypropylene-based fibrous adsorbents showed similar adsorption properties for uranium from sea water. The adsorption tests proved the performance of the polypropylene-based fibrous adsorbents as a promising material for uranium recovery from sea water. In addition, uranium uptake of fibrous adsorbents increased in proportion to the volume of sea water. © 1993 John Wiley & Sons, Inc.     

Binding of heavy metal ions by chemically modified woods

Three chemically modified woods were prepared and used for the binding of heavy metal ions. Wood–polythylenimine composite (wood–PEI) was found to be effective for the adsorption of heavy metal ions such as Hg²⁺, Cu²⁺, and other metal ions which tend to form stable ammine complexes. Adsorption of metal ions on a wood–PEI derivative containing dithiocarbamate group (DTC–wood) was higher than that by wood–PEI. Especially, the reactivity of DTC–wood with Hg²⁺ was quite high and the binding capacity of about 5 mmol/g was easily attainable. The rate of adsorption on these wood-based adsorbents was very high, and adsorption of about 70% of total binding capacity was accomplished in the first 1 h. This may be due to a highly porous structure and a hydrophilic nature of the wood which constitutes the skeleton of the adsorbents. Amidoximated wood (AO–wood) prepared by the reaction of cyanoethylated wood with hydroxylamine showed selective adsorptivity for uranium in sea water. More than 53% of uranium in the sea water used was adsorbed by the AO–wood.     

An investigation of engineering parameters for the use of immobilized biomass particles in biosorption

Immobilized, inactive mycelia of Rhizopus arrhizus are preferential to native biomass for use in the biosorption of metal ions. Refinement of a proprietary immobilization technique previously developed at McMaster University enabled production of particles of immobilized Rhizopus arrhizus biomass having a 12–23% wt of polymer additive. The effects of production stage parameters on the intrinsic uptake capacity of the immobilized biomass were examined. Kinetic experiments showed the following trends: a decrease in the weight percent of the added polymer leads to an increase in the apparent uranium uptake capacity of the immobilized biomass particles far a given contact time. A decrease in the particle size improved the kinetics of metal uptake and led to an increase in the apparent uranium uptake capacity for the same contact time. An increase in the initial concentration of the uranium solution caused equilibrium conditions to be attained faster.     

How to Study Biofilms after Microbial Colonization of Materials Used in Orthopaedic Implants

Over the years, various techniques have been proposed for the quantitative evaluation of microbial biofilms. Spectrophotometry after crystal violet staining is a widespread method for biofilm evaluation, but several data indicate that it does not guarantee a good specificity, although it is rather easy to use and cost saving. Confocal laser microscopy is one of the most sensitive and specific tools to study biofilms, and it is largely used for research. However, in some cases, no quantitative measurement of the matrix thickness or of the amount of embedded microorganisms has been performed, due to limitation in availability of dedicated software. For this reason, we have developed a protocol to evaluate the microbial biofilm formed on sandblasted titanium used for orthopaedic implants, that allows measurement of biomass volume and the amount of included cells. Results indicate good reproducibility in terms of measurement of biomass and microbial cells. Moreover, this protocol has proved to be applicable for evaluation of the efficacy of different anti-biofilm treatments used in the orthopaedic setting. Summing up, the protocol here described is a valid and inexpensive method for the study of microbial biofilm on prosthetic implant materials.     

海水替代淡水在江蓠加工中的应用研究

用海水替代淡水进行江蓠加工生产,是解决江蓠加工需要消耗大量淡水的有效途径,具有良好的社会效益和经济效益。实验结果表明,通过pH控制,使海水的pH=6．O～6,5,使用0．55％HCl作为酸化液,0.40％H2C2O4作为二次酸化、增白液,海水完全可以用于江蓠的加工生产,替代率高达73％。     

Amidoxime resins based on poly(acrylonitrile-co-vinylidene chloride-co-divinylbenzene) and their behavior in uptake of uranium from sea water

Amidoxime resins were derived from poly(acrylonitrile-co-vinylidene chloride-co-divinyl-benzene) beads, which were prepared by suspension polymerization of the ternary monomeric mixtures in the presence of 4-methyl-2-pentanone (MIBK) or 1,2-dichloroethane (DCE) as the diluent (porogen), in order to clarify the effect of copolymerized vinylidene chloride on properties of the resulting amidoxime resins. Pore structure analyses of the copolymers as well as of their amidoximated derivatives clarified that MIBK yields larger pores than does DCE and then the latter gives larger specific surface areas than does the former. On the other hand, chemical properties of the amidoximated resins, such as anionexchange capacities and uranyl ion uptake, were not eseentially affected by the diluent species, indicating that both MIBK and DCE as the porogen lead to the amidoxime resins with almost the same ability in recovery of uranium from sea water. The uranium recovery decreased with increase in the vinylidene chloride content, but the decrease in the recovery was minor up to the 10 mol % of vinylidene chloride. It was also clarified that the uranium recovery by the amidoxime resins containing vinylidene chloride is greatly enhanced by the alkali treatment. © 1994 John Wiley & Sons, Inc.     

Nanomaterial processing strategies in functional hybrid materials for wastewater treatment using algal biomass

Algal cultivation has tremendous potential in wastewater treatment, and its simultaneous biomass production has advantages for the production of value added products such as biodiesel, fertilizers and pharmaceuticals. Some obstacles to obtaining a productive biological water treatment and bioenergy system are the harvesting and processing of biomass. Such issues can be addressed using nano‐bio hybridization approaches by simplifying the microbial harvesting step along with increasing the efficiency of wastewater treatment. This review highlights studies within our research group that are based on the fabrication of functional hybrid materials using algal biomass, including: (i) electrospun nanofibers; (ii) laminar nanomaterials; and (iii) magnetic nanoparticles impregnated in a polymer. All of these techniques have been used for the removal of waste pollutants such as nitrate and phosphate ions. The multidisciplinary techniques have potential to provide effective algal culture systems for industrial applications, while having a significant impact on wastewater treatment. © 2017 Society of Chemical Industry     

Biosorptive uranium uptake by a Pseudomonas strain: characterization and equilibrium studies

The biosorptive uranium(VI) uptake capacity of live and lyophilized Pseudomonas cells was characterized in terms of equilibrium metal loading, effect of solution pH and possible interference by selected co‐ions. Uranium binding by the test biomass was rapid, achieving >90% sorption efficiency within 10 min of contact and the equilibrium was attained after 1 h. pH‐dependent uranium sorption was observed for both biomass types with the maximum being at pH 5.0. Metal uptake by live cells was not affected by culture age and the presence of an energy source or metabolic inhibitor. Sorption isotherm studies at a solution pH of either 3.5 or 5.0 indicated efficient and exceptionally high uranium loading by the test biomass, particularly at the higher pH level. At equilibrium, the lyophilized Pseudomonas exhibited a metal loading of 541 ± 34.21 mg g^?1 compared with a lower value by the live organisms (410 ± 25.93 mg g^?1). Experimental sorption data showing conformity to both Freundlich and Langmuir isotherm models indicate monolayered uranium binding by the test biomass. In bimetallic combinations a significant interference in uranium loading was offered by cations such as thorium(IV), iron(II and III), aluminium(III) and copper(II), while the anions tested, except carbonate, were ineffective. Uranium sorption studies in the presence of a range of Fe³⁺ and SO₄^2? concentrations indicate a strong inhibition (80%) by the former at an equimolar ratio while more than 70% adsorption efficiency was retained even at a high sulfate level (30 000 mg dm^?3). Overall data indicate the suitability of the Pseudomonas sp biomass in developing a biosorbent for uranium removal from aqueous waste streams. © 2001 Society of Chemical Industry     

磷脂脂肪酸分析在湖泊沉积物微生物生态学研究中的应用

磷脂脂肪酸分析(PLFA)技术是近年来出现的一种新的微生物生态学研究方法,它是利用微生物细胞内磷脂脂肪酸的成分和含量相对稳定的原理,通过对环境样品中的磷脂脂肪酸进行提取和分析,以获得微生物生物量和群落结构变化的信息,已被应用于土壤、水体和植物根系等环境中微生物生态学的研究.综述了PLFA技术在湖泊沉积物微生物生态学研究中的应用,同时指出了PLFA技术存在的问题及其发展前景.     

Flotation of uranium from uranium ores in canada: Part I-flotation results with elliot lake uranium ores using chelating agents as collectors

About 150 flotation tests were done on Elliot Lake ore with 15 reagents as collectors in order to screen and choose an attractive collector for uranium flotation. Several variables were studied including pH, conditioning time and mode of collector addition. The tests were done in a Denver or Agitair subacration cell. The particle size of the ore was kept at 85% below-325 mesh. Three reagents (Kelex 100, TOPO, and cupferron) were identified as having the most promise. The best results were obtained with cupferron, where 93-95% of the uranium was recovered in 25-30% of the mass of original ore. Radium in the tails varied between 15 and 30 pCi/g depending on the mass of uranium floated. Radium was recovered in proportion to uranium in the tests done at neutral pH. The preconcentration results obtained by flotation alone were comparable to those obtained by Raicevic of CANMET using pyrite flotation and wet high intensity magnetic separation of uranium. The consumption of cupferron was 4 kg/Mg ore for each flotation stage. This was 10-15 times larger than the collector usage in conventional oxide flotation. This scheme did not require other reagents as depressants, activators or modifiers. Reproducibility was good and similar recoveries were obtained with fresh or old ores, and with distilled or mine water. The selectivity of cupferron for uranium in the ore studied was outstanding.     

Uranium(VI) Removal from Aqueous Solution by Poly(Amic Acid)-Modified Marine Fungus

Fusarium sp. #ZZF51, marine-derived mangrove endophytic fungus, was chemically modified by poly(amic acid) to enhance its potential of uranium(VI) biosorption in aqueous solution. Compared with uranium(VI) removal of the pristine biomass, the maximum uranium(VI) adsorption capacity of the modified biomass increased 9.5-fold under the optimal condition of pH 5.0, S/L 0.4, and equilibrium time 180 min. Kinetic study showed that the process follows the pseudo-second-order kinetic model, which indicates that chemical reaction controls the adsorption rate. The thermodynamic experimental data fit well with Langumir, Freundlich, and Temkin isotherms, and their R ² values are 0.954, 0.963, and 0.986, respectively. FTIR spectroscopic analysis of the native, modified, and uranium-loaded biomass demonstrated the involvement of carboxyl, amide, and hydroxyl groups on the surface of fungus Fusarium sp. #ZZF51 cell wall in the adsorption of uranium(VI).     

Recovery of uranium from sea water. IV. Influence of crosslinking reagent of the uranium adsorption of macroreticular chelating resin containing amidoxime groups

Macroreticular chelating resins (RNH) containing amidoxime groups with various degrees of crosslinking were synthesized by using various amounts of ethyleneglycol dimethacrylate (1G), dimethyleneglycol dimethacrylate (2G), triethyleneglycol dimethacrylate (3G), tetraethyleneglycol dimethacrylate (4G), and nanoethyleneglycol dimethacrylate (9G) as crosslinking reagent. The effect of crosslinking reagents on the pore structure, ion exchange capacity, swelling ratio, and adsorption ability for uranium of RNH was investigated. RNH (RNH–1G) prepared by using 1G were showed to have macroreticular structures by the measure of specific surface area. RNH–1G had the high adsorption ability and physical stability. Though RNH (RNH–4G) obtained by using 4G have little macroreticular structure (macropore), these resins showed the high adsorption ability for uranium by the treatment with 0.1 mol dm^?3 NaOH at 30°C for 15 h (alkali treatment). These results suggest that the formation of not only the favorable macropore but also the micropore is important for the effective recovery of uranium in sea water, whereas RNH–4G was defined to be low physical and chemical stability. For the preparation of RNH which have effective pore structure for the recovery of uranium, chemical, and physical stability, the simultaneous use of divinylbenzene (DVB) and 1G or 4G as crosslinking reagent was examined (abbreviated as RNH–DVB–1G and RNH–DVB–4G). The specific surface area of RNH–DVB–1G increased with an increase of 1G used. These RNH–DVB–1G have been shown the high adsorption ability for uranium. On the other hand, the specific surface area and adsorption ability for uranium of RNH–DVB–4G decreased with an increase of 4G used. Repeated use did not cause the deterioration of both RNH–DVB–1G and RNH–DVB–4G. This result suggests that the simultaneous use of DVB and 1G or 4G contributed the improvement of chemical and physical stability. In particular, RNH–DVB–1G has the effective macropore and micropore for the recovery of uranium.     

Start up of biological sequencing batch reactor (SBR) and short‐term biomass acclimation for polyhydroxyalkanoates production

BACKGROUND: The adaptation/selection of mixed microbial cultures under feast/famine conditions is an essential step for polyhydroxyalkanoates (PHA) production. This study investigated the short‐term adaptation of a mixed microbial culture (activated sludge) during the start up of a sequencing batch reactor (SBR). RESULTS: Four different SBR runs were performed starting from different inocula and operated at the same organic load rate (8.5 gCOD L^?1 d^?1) and hydraulic retention time (1 day). At 3–7 days from SBR start up, the selected biomass was able to store PHA at comparable rate and yield with those obtained after long‐term acclimation. Independently from the time passed, a short feast phase was the key parameter to obtain PHA storage at high rate and yield in the following accumulation stage (244 mgCOD g^?1CODnonPolym h^?1 for specific storage rate and 48% COD COD^?1 as PHA content in the biomass). The DGGE profiles showed that the good storage performance and the structure of the microbial community were not fully correlated. CONCLUSIONS: The results suggest a new strategy for operating the PHA accumulation stage directly in the SBR, after very short biomass adaptation, instead of using two separate reactors for biomass enrichment and PHA accumulation, respectively. © 2012 Society of Chemical Industry     

好氧颗粒污泥技术及研究进展

近年来,水资源短缺以及水体污染问题日益严峻。传统的活性污泥生物水处理技术由于产生大量剩余污泥,在某种程度上限制和影响了该方法在废水处理中的应用。由微生物自凝聚形成的特殊生物膜——好氧颗粒污泥由于具有污泥颗粒结构紧凑致密、沉降性能好、生物量较高,同时具备多种微生物功能、剩余污泥量较少等优势,而备受关注。本文重点论述了好氧颗粒污泥的结构特征、表观气速与溶氧水平,有机负荷、金属离子、代谢方式等外部环境因子对污泥颗粒快速培养和形成过程的影响,微生物菌群结构与颗粒形成机制、以及影响颗粒长期运行过程中稳定性缺失的主要原因,提高好氧颗粒污泥的稳定性的常用措施,以提高人们对好氧颗粒污泥的认识,推动好氧颗粒污泥技术在废水领域中的应用。     

锰氧化物负载沸石固定床离子交换柱去除铀(VI)的研究

The adsorption of uranium (VI) on the manganese oxide coated zeolite (MOCZ) from aqueous solution was investigated in a fixed-bed column. The experiments were conducted to investigate the effects of bed height, flow rate, particle size, initial concentration of uranium (VI), initial pH, presence of salt and competitive ions. The U-uptake by MOCZ increased with initial uranium (VI) concentration and bed height, but decreased as the flow rate and particle size increased. In the presence of salt and competitive ions, the breakthrough time was shorter. The ad-sorption capacity reached a maximum at pH of 6.3. The Thomas model was applied to the experimental data to de-termine the characteristic parameters of the column for process design using linear regression. The breakthrough curves calculated from the model were in good agreement with the experimental data. The BDST model was used to study the influence of bed height on the adsorption of uranium (VI). Desorption of uranium (VI) in the MOCZ column was investigated. The column could be used for at least four adsorption-desorption cycles using 0.1 mol•L－1 NaHCO3 solution as the elution. After desorption and regeneration with deionized water, MOCZ could be reused to adsorb uranium (VI) at a comparable capacity. Compared to raw zeolite, MOCZ showed better capacity for uranium (VI) removal.