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Waste Streams (waste + stream)
Selected AbstractsRECOVERY OF SINAPIC ACID FROM A WASTE STREAM IN THE PROCESSING OF YELLOW MUSTARD PROTEIN ISOLATEJOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2008N. PRAPAKORNWIRIYA ABSTRACT A large amount of waste permeates generated from the processing of yellow mustard protein was concentrated fivefold using a nanofilter with a molecular weight cut off of 1,000 Da, while approximately 74% of sinapic acid was retained. Sinapic acid was then released from sinapine, its esterified form, by an alkaline hydrolysis. The hydrolyzed solution was acidified to prevent oxidation of the sinapic acid and to precipitate the remaining proteins. Subsequently, sinapic acid and other phenolics were extracted by a two-stage extraction using a mixture of diethyl ether and ethyl acetate (1:1), 165-min extraction time and permeate-to-solvent ratio of 1:2. Approximately 95% of the sinapic acid in the acidified permeate was finally concentrated in the solvent phase. PRACTICAL APPLICATIONS This development has led to an economical process to recover phenolics and to treat effluent from a process of oilseed protein while reducing the use of water during the extraction of protein. A reduction of water usage makes the processing of oilseed protein isolate more economically attractive, and the recovered phenolics may find a use as a nutraceutical. The developed process is not only limited to the recovery of phenolics from mustard, but also applied for recovering phenolic acids, specifically sinapic acid, from waste water from membrane processing of protein from mustard and similar polyphenol-containing oilseeds. [source] Optimization of process parameters by Taguchi method in the recovery of lactose from whey using sonocrystallizationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2010S. R. Patel Abstract Anti-solvent crystallization of lactose in the presence of ultrasound will reduce crystal size and the level of agglomeration as compared to the commercial cooling crystallization. It offers a potential route to enhance the physical properties as well as the rapid recovery of lactose. Since lactose recovery itself can reduce biological oxygen demand of whey by more then 80%, recovery of lactose from dairy waste stream (whey) solves the problems of dairy industries by improving economics of whey utilization and pollution reduction. In the present study, recovery of lactose from partially deproteinated whey using an anti-solvent (acetone) by sonocrystallization was optimized for finding the most influencing operating parameters; such as sonication time, anti-solvent concentration, initial lactose concentration in the whey and initial pH of sample mixture at three levels using L9 -orthogonal method. The responses were analyzed for recovery of lactose from whey. The anti-solvent concentration and the sonication time were found to be most influencing parameters for the recovery of lactose and the recovery of lactose was found to be 89.03% at the identified optimized level. The crystal size distribution of recovered lactose was found to be narrower (2.5 , 6.5 ,m) as compared to the commercial lactose crystals (3.5 , 9.5 ,m). (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Production of paramylon, a ,-1,3-glucan, by heterotrophic cultivation of Euglena gracilis on potato liquorENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 2 2010Bozidar, antek Abstract Euglena gracilis is shown to be able to grow on potato liquor as the main medium component leading to an interesting biotechnological product represented by paramylon , a ,-1,3-glucan , and, at the same time, revaluating an otherwise annoying waste stream of the potato-starch industry. Paramylon mass fractions of about 75% are obtained for biomass concentrations of 15,g/L during simple batch cultivation under heterotrophic conditions. Supplementation of the growth medium with glucose and the vitamins B1 and B12 are shown to improve growth rate as well as paramylon content. E. gracilis grows best at about 27.5°C without requiring pH control. [source] Maximizing resource recovery from waste streamsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2003Tim Grant Resource conservation and waste management have become two sides of the same argument. According to the Institutefor Local Self Reliance in the US., the recycling revolution begun in the l960s was a reaction "to the levels of waste in our economy and the pollution and suffering these habits cause worldwide" [1,2]. However, the recycling targetsetting of the early 1990s was focused on diversion from landfill, and it has taken another 10 years for the focus to shift back to the resource values approach, driven largely by the application of Life Cycle Assessment to the waste management system. This paper examines materials in the waste stream to determine the "value proposition" in each material group, and to examine options for efficient resource use and recovery. Specifically, it discusses waste management issues associated with clean fill, food waste, timber waste, concrete and bricks, green waste, paper and board, metals, plastics, and glass. [source] Automating hierarchical environmentally-conscious design using integrated software: VOC recovery case studyENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2003Hui Chen Traditionally, chemical process design and optimization has mainly been based on economic considerations. Currently, the scope is being extended to include environmentally-conscious process design (ECD). ECD will be facilitated by the emergence of integrated design methodologies and tools. The objectives of this paper are to present a hierarchical design methodology for environmentally-conscious process design, and an integrated assessment and optimization software. An application for the recycle of VOCs from a gaseous waste stream is presented using this design methodology and software. Revenue increased and environmental impacts were reduced. The net present value for the optimum design is approximately $900,000, which is much higher than the base case design, ,$2,498,200. A composite environmental index decreases from 1.19 × 10,4 in the base case to about 1.30 × 10,5 in the optimum case. This automated tool along with the embedded design methodology provides an effective and efficient way to perform environmentally-conscious chemical process design and optimization. [source] Endocrine responses of Fundulus heteroclitus to effluent from a bleached-kraft pulp mill before and after installation of reverse osmosis treatment of a waste streamENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Monique G. Dubé Abstract Implementation of process changes on the nonbleaching side of bleached kraft pulp mill (BKPM) operations has increased in recent years to maximize resource use and to minimize residual environmental effects of discharged effluents. The objective of this study was to determine if reverse osmosis (RO) treatment of evaporator and digester clean condensates reduced or removed the effects of a BKPM effluent on reproductive endocrine function of the estuarine killifish, Fundulus heteroclitus (mummichog). Comparison of data collected before (1997) and after (1998), the years of the process change, showed that the potential of the combined mill effluent to depress plasma testosterone levels after 30 and 57 d of exposure to an environmentally relevant effluent concentration (1%) was reduced after RO treatment of condensates. However, in vitro production of some sex steroids was depressed with a 1% effluent exposure after the process change. In addition, in 1998, depression of plasma testosterone levels in effluent-exposed fish was present at higher effluent concentrations (5%). These results are significant because they suggest that condensates may be a source of endocrine-disrupting compounds in BKPM effluents and RO may reduce their discharge. [source] Removal of H2S and volatile organic sulfur compounds by silicone membrane extractionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2009I. Manconi Abstract BACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H2S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone-based membrane to simultaneously remove H2S and VOSC. An extractive membrane reactor allows the selective withdrawal of VOSC and H2S simultaneously from the waste stream, while preventing direct contact between the waste stream and the absorbing solution and/or the biological treatment system. The influence of the sulfur compounds, membrane characteristics, extractant and pH was studied. RESULTS: Sulfide and the VOCS studied, i.e. methanethiol (MT), ethanethiol (ET) and dimethylsulfide (DMS) were removed from the synthetic wastewater using a silicone rubber membrane. Methanethiol showed the highest (8.72 × 10,6 m s,1) overall mass transfer coefficient (kov) and sulfide the lowest kov value (1.23 × 10,6 m s,1). Adsorption of the VOCS into the silicone membrane reduced the overall mass transfer coefficient. The kov when using Fe(III)EDTA, as extractant (5.81 × 10,7 m s,1) for sulfide extraction was one order of magnitude lower than with anaerobic water (2.54 × 10,6 m s,1). On the other hand, the sulfide removal efficiency with Fe(III)EDTA, was higher (84%) compared with anaerobic water (60%) as extractant. An additional mass transfer resistance was formed by elemental sulfur which remained attached to the membrane surface. CONCLUSIONS: Extraction of sulfide and VOCS from a synthetic wastewater solution through a silicone rubber membrane is a feasible process as alternative to the techniques developed to treat VOSC emissions. Optimizing the aqueous absorption liquid can increase the efficiency of extraction based processes. Copyright © 2008 Society of Chemical Industry [source] Foam fractionation of ,-lactalbumin and ,-lactoglobulin from a whey solutionASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009A. P. Shea Abstract Whey, a byproduct of cheese production, is often considered a waste stream. Separation and purification of whey proteins is a difficult and expensive task. Occasionally, it is transported out of the dairy plant for a per volume charge. One possible method to reduce the waste volume and disposal cost is to concentrate whey by foam fractionation and potentially produce a valuable coproduct, a concentrated whey protein solution. Foam fractionation is an adsorptive bubble separation method based on the hydrophobic/hydrophilic properties of proteins. In this study, foam fractionation was evaluated for the concentration of whey proteins, specifically ,-lactalbumin and ,-lactoglobulin, from a dilute whey protein solution. The effects of initial whey protein concentration (0.075 and 0.15 mg/ml), pH (3.8,5.5), superficial gas velocity (0.85 and 0.95 cm/s) and temperature (4 and 65 °C) on protein enrichment and recovery were examined. Higher enrichment was achieved with the lower initial protein concentration (0.075 mg/ml), and at pH values that were near the isoelectric points (pI) of ,-lactalbumin and ,-lactoglobulin (pH 3.8, 4.2, 4.5, and 5.2). Higher superficial gas velocity enhanced the amount of proteins recovered with a decrease in the enrichment. Cold temperature treatment and partial heat denaturation of whey proteins reduced enrichment and increased protein recovery simultaneously. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Maximizing resource recovery from waste streamsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 4 2003Tim Grant Resource conservation and waste management have become two sides of the same argument. According to the Institutefor Local Self Reliance in the US., the recycling revolution begun in the l960s was a reaction "to the levels of waste in our economy and the pollution and suffering these habits cause worldwide" [1,2]. However, the recycling targetsetting of the early 1990s was focused on diversion from landfill, and it has taken another 10 years for the focus to shift back to the resource values approach, driven largely by the application of Life Cycle Assessment to the waste management system. This paper examines materials in the waste stream to determine the "value proposition" in each material group, and to examine options for efficient resource use and recovery. Specifically, it discusses waste management issues associated with clean fill, food waste, timber waste, concrete and bricks, green waste, paper and board, metals, plastics, and glass. [source] Comparative measures of the toxicity of component chemicals in aircraft deicing fluidENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Jeffrey S. Cornell Abstract Acraft deicingoperationsarea necessarypart of safe air travel, but release large quantities of aircraft deicing fluids (ADFs) to the environment. Effective measures to mitigate the environmental impacts of deicing operations are hindered because of the negative effects some ADF chemicals have on treatment systems and because of the poorly characterized toxicity of ADF components. This research investigated the contributions of environmentally significant concentrations of selected ADF components to the toxicity of ADF-containing waste streams, and to the inhibition of biodegradation of propylene glycol (PG), the most important component of ADF. The component chemicals studied were PG, the corrosion inhibitor 4(5)-methylbenzotriazole (MeBT; common name: tolyltriazole), and proprietary mixes of corrosion inhibitors, buffers, and surfactants referred to as the additive package or AdPack. Relative to PG alone, the different additives increased the toxicity of ADF and decreased PG biodegradation rates. In enrichments of soil microorganisms acclimated to ADF, the MeBT component significantly decreased cell growth rates and yields, and inhibited PG biodegradation to a greater extent than the AdPack. Microtox® tests indicated that MeBT is the ADF component most toxic to microorganisms. However, acute aquatic toxicity tests indicated that the AdPack components were more toxic than MeBT to Ceriodaphnia dubia and Pimephales promelas, although both components were more toxic than PG alone. [source] New concepts of microbial treatment processes for the nitrogen removal in wastewaterFEMS MICROBIOLOGY REVIEWS, Issue 4 2003Ingo Schmidt Abstract Many countries strive to reduce the emissions of nitrogen compounds (ammonia, nitrate, NOx) to the surface waters and the atmosphere. Since mainstream domestic wastewater treatment systems are usually already overloaded with ammonia, a dedicated nitrogen removal from concentrated secondary or industrial wastewaters is often more cost-effective than the disposal of such wastes to domestic wastewater treatment. The cost-effectiveness of separate treatment has increased dramatically in the past few years, since several processes for the biological removal of ammonia from concentrated waste streams have become available. Here, we review those processes that make use of new concepts in microbiology: partial nitrification, nitrifier denitrification and anaerobic ammonia oxidation (the anammox process). These processes target the removal of ammonia from gases, and ammonium-bicarbonate from concentrated wastewaters (i.e. sludge liquor and landfill leachate). The review addresses the microbiology, its consequences for their application, the current status regarding application, and the future developments. [source] Stabilized and Immobilized Bacillus subtilis Arginase for the Biobased Production of Nitrogen-Containing ChemicalsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Abstract L -Ornithine could serve as an intermediate in the biobased production of 1,4-diaminobutane from L -arginine. Using the concept of biorefinery, L -arginine could become widely available from biomass waste streams via the nitrogen storage polypeptide cyanophycin. Selective hydrolysis of L -arginine to L -ornithine is difficult to perform chemically, therefore the stabilization and immobilization of Bacillus subtilis arginase (EC,3.5.3.1) was studied in a continuously stirred membrane reactor system. Initial pH of the substrate solution, addition of L -aspartic acid and reducing agents all appeared to have an effect on the operational stability of B. subtilis arginase. A remarkably good operational stability (total turnover number, TTN=1.13,108) at the pH of arginine free base (pH,11.0) was observed, which was further improved with the addition of sodium dithionite to the substrate solution (TTN>1,109). B. subtilis arginase was successfully immobilized on three commercially available epoxy-activated supports. Immobilization on Sepabeads EC-EP was most promising, resulting in a recovered activity of 75% and enhanced thermostability. In conclusion, the stabilization and immobilization of B. subtilis arginase has opened up possibilities for its application in the biobased production of nitrogen-containing chemicals as an alternative to the petrochemical production. [source] Removal of H2S and volatile organic sulfur compounds by silicone membrane extractionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2009I. Manconi Abstract BACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H2S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone-based membrane to simultaneously remove H2S and VOSC. An extractive membrane reactor allows the selective withdrawal of VOSC and H2S simultaneously from the waste stream, while preventing direct contact between the waste stream and the absorbing solution and/or the biological treatment system. The influence of the sulfur compounds, membrane characteristics, extractant and pH was studied. RESULTS: Sulfide and the VOCS studied, i.e. methanethiol (MT), ethanethiol (ET) and dimethylsulfide (DMS) were removed from the synthetic wastewater using a silicone rubber membrane. Methanethiol showed the highest (8.72 × 10,6 m s,1) overall mass transfer coefficient (kov) and sulfide the lowest kov value (1.23 × 10,6 m s,1). Adsorption of the VOCS into the silicone membrane reduced the overall mass transfer coefficient. The kov when using Fe(III)EDTA, as extractant (5.81 × 10,7 m s,1) for sulfide extraction was one order of magnitude lower than with anaerobic water (2.54 × 10,6 m s,1). On the other hand, the sulfide removal efficiency with Fe(III)EDTA, was higher (84%) compared with anaerobic water (60%) as extractant. An additional mass transfer resistance was formed by elemental sulfur which remained attached to the membrane surface. CONCLUSIONS: Extraction of sulfide and VOCS from a synthetic wastewater solution through a silicone rubber membrane is a feasible process as alternative to the techniques developed to treat VOSC emissions. Optimizing the aqueous absorption liquid can increase the efficiency of extraction based processes. Copyright © 2008 Society of Chemical Industry [source] Anaerobic biodegradation of two-phase olive mill solid wastes and liquid effluents: kinetic studies and process performanceJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2006Rafael Borja Abstract The new two-phase olive oil mills produce three identifiable and separate waste streams, namely (1) the wash waters from the initial cleansing of the fruit, (2) the aqueous solid residues from the primary centrifugation and (3) the wash waters from the secondary centrifugation. As well as offering process advantages, they also consume less water. Therefore the solid residue, two-phase olive mill solid waste (OMSW), has a high organic matter concentration, giving it an elevated polluting load, and cannot be easily handled by traditional technology which deals with the conventional three-phase olive cake. In addition, the new two-phase olive mill effluents (TPOME) are made up of a mixture of effluents (1) and (3), the total volume of TPOME generated being ,0.25 dm3 kg,1 olives processed. This review aims to report the main features and characteristics of two-phase OMSW and TPOME as compared with the classical olive cake and olive mill wastewater (OMW) derived from the three-phase manufacturing process. The advantages and disadvantages of the two-phase decanting process are summarised. The anaerobic digestibility of two-phase OMSW using different influent substrate concentrations is reported. Kinetic studies of anaerobic digestion of two-phase OMSW are also reviewed and summarised, as well as mass balances to predict the behaviour of the reactor and simplified kinetic models for studying the hydrolysis, acidogenic and methanogenic steps of one- and two-stage anaerobic digestion of OMSW. The review also includes the following: assays of anaerobic digestion of wastewaters from the washing of olives, of olive oil and the two together using fluidised beds and hybrid reactors; the kinetics, performance, stability, purification efficiencies and methane yield coefficients. Copyright © 2006 Society of Chemical Industry [source] Anaerobic biodegradation of phenol in sulfide-rich mediaJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2004Patricia Olguín-Lora Abstract In the refinery industry, the washing processes of middle-distillates using caustic solutions generate phenol- and sulfide-containing waste streams. The spent caustic liquors generated contain phenols at concentrations higher than 60 g dm,3(638.3 mmol dm,3). For sulfur compounds, the average sulfide concentration was 48 g dm,3(1500 mmol dm,3) in these streams. The goal of this study was to evaluate the specific impact of phenol and sulfide concentrations towards the phenol-biodegradation activity of a phenol-acclimated anaerobic granular sludge. An inhibition model was used to calculate the phenol and sulfide inhibitory concentrations that completely stopped the phenol-biodegradation activity (IC100). A maximum phenol-biodegradation activity of 83 µmol g,1 VSS h,1 was assessed and the IC100 values were 21.8 mmol dm,3 and 13.4 mmol dm,3 for phenol and sulfide respectively. The limitation of the phenol biodegradation flow by phenol inhibition seemed to be related to the more important sensitivity of phenol-degrading bacteria. The up-flow anaerobic sludge bed reactor operating in a non-phenol-dependent inhibition condition did not present any sensitivity to sulfide concentrations below 9.6 mmol dm,3. At this residual concentration, the pH and bisulfide ions' concentration might be responsible for the general collapsing of the reactor activity. Copyright © 2004 Society of Chemical Industry [source] Incentives for pollution abatement: Regulation, regulatory threats, and non-governmental pressuresJOURNAL OF POLICY ANALYSIS AND MANAGEMENT, Issue 3 2003Kathryn Harrison In the last decade, voluntary efforts by firms to reduce their environmental impacts have received increasing attention from both policymakers and scholars. This article discusses polluters' incentives to reduce their releases. In particular, using data from Canada's National Pollutant Release Inventory, it examines the impacts of conventional regulation, threats of regulation, and non-governmental pressures facilitated by public dissemination of information about pollutant releases. The vast majority of reductions reported to the inventory to date were found not to be voluntary, as has often been assumed, but are, rather, the result of direct regulation of a relatively small number of polluters. Strong effects of federal regulation were found among other sources, as well, with much weaker responses to the mere threat of regulation. However, of concern are the growth of less visible waste streams,such as land disposal and underground injection,as well as transfers of wastes to other communities. Finally, evidence is reported that some waste streams are increasing in toxicity, an effect that may outweigh the benefits of reductions in releases. © 2003 by the Association for Public Policy Analysis and Management. [source] Quality Concepts for the Improved Use of Recycled Polymeric Materials: A ReviewMACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2008Francisco Vilaplana Abstract Polymeric waste materials should be considered resources for the manufacture of new products through recycling processes, with a similar status to virgin fossil-based plastics and biopolymers from renewable resources. Several efforts can be made to achieve this qualitative quantum leap in plastics recycling, and consequently introduce recycled products, with competitive performance, to the market. Scientific knowledge about the degradation processes during the life cycle and the development of fast and reliable analytical methods for the quality assessment of recycled plastics are fundamental to guarantee their performance in new applications. Different strategies,restabilisation, rebuilding, compatibilisation, and addition of elastomers and fillers,can be used to upgrade the structure and properties of polymeric waste streams. This review discusses recent developments in the mechanical recycling of plastics, focusing on how to produce quality materials from waste streams and, thus, contribute to a sustainable management of resources and energy. [source] T-AKE: Acquiring the Environmentally Sound Ship of the 21st CenturyNAVAL ENGINEERS JOURNAL, Issue 3 2006Cdr. Stephen P. Markle USN (Ret.) P.E. Department of Defense (DoD) program managers are increasingly challenged with the difficulties of balancing the risks associated with cost, schedule, and performance in an era of intense competition for increasingly scarce resources. Requirements associated with environmental, safety, and health (ESH), in the context of thirty to forty-year service lives, have not been consistently, or in some cases adequately, addressed in DoD programs. Environmental protection (EP) requirements generally do not fit the normal requirements generation and product synthesis model typically applied to weapon system development. As with all requirements, early identification is the key to integration into the total system. Recognition that EP requirements must be integrated at program conception led to development of the ESH Integration Model by the U.S. Navy Lewis and Clark (T-AKE) Auxiliary Cargo Ammunition Ship Program. Institutionalization of this model has enabled the T-AKE Program to establish EP performance requirements for the twelve-ship class that substantially reduce the environmental footprint of the Navy. Compared to the fifteen ships that it will be replacing, T-AKE will require fifty percent less manning and reduce waste streams by seventy percent enabling an annual life cycle cost savings of $5M in ashore waste disposal costs. The T-AKE Program has been the first to achieve the Chief of Naval Operations vision for the "Environmentally Sound Warship of the 21st Century" through design integration of EP requirements. [source] Prototypes for building applications based on thermoplastic composites containing mixed waste plasticsPOLYMER COMPOSITES, Issue 2 2002M. Xanthos Automotive shredder residue (ASR) and a complex residue obtained as a by-product in the tertiary recycling of nylon-6 fibers from used carpets were evaluated as potential additives in thermoplastic composites to be used for building applications. Prototype blocks were prepared by the "intrusion" process using various ratios of the waste streams and low-density polyethylene (LDPE) in the absence of compatibilizers. Hence, product morphologies and corresponding properties were largely controlled through processing. They were evaluated for their short-term and longterm mechanical properties, flammability, thermal conductivity, and heavy-metal and total organic carbon leaching characteristics. Encapsulation of the waste feedstock by LDPE during molding in a single-screw extruder significantly reduced the leachable content. In an effort to further reduce the leachable content, the mixtures were processed in two stages by precompounding in adevolatilizing twin-screw extruder prior to molding. In comparison to the as-received wastes, improved homogenization decreased the leachable heavy-metal content by at least 98%. The carpet residue feedstock consisting of polypropylene, styrene-butadiene rubber and calcium carbonate appears to be an attractive low-cost, high-volume material with consistent properties and could be used as filler in thermoplastic composites. Comparison of their performance characteristics suggested that the carpet residue composites would be favored versus ASR composites as replacement of the wood thermal barrier components in a novel steel-based stud assembly. [source] Using non-invasive magnetic resonance imaging (MRI) to assess the reduction of Cr(VI) using a biofilm,palladium catalystBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010D.A. Beauregard Abstract Industrial waste streams may contain contaminants that are valuable like Pd(II) and/or toxic and mutagenic like Cr(VI). Using Serratia sp. biofilm the former was biomineralized to produce a supported nanocrystalline Pd(0) catalyst, and this biofilm,Pd heterogeneous catalyst was then used to reduce Cr(VI) to less dangerous Cr(III) at room temperature, with formate as the electron donor. Cr(VI)(aq) is non-paramagnetic while Cr(III)(aq) is paramagnetic, which enabled spatial mapping of Cr species concentrations within the reactor cell using non-invasive magnetic resonance (MR) imaging experiments. Spatial reactivity heterogeneities were thus examined. In batch reactions, these could be attributed primarily to heterogeneity of Pd(0) distribution and to the development of gas bubbles within the reactor. In continuous flow reactions, spatial reactivity heterogeneities resulted primarily from heterogeneity of Cr(VI) delivery. Biotechnol. Bioeng. 2010;107: 11,20. © 2010 Wiley Periodicals, Inc. [source] Analysis of a Microbial Community Oxidizing Inorganic Sulfide and MercaptansBIOTECHNOLOGY PROGRESS, Issue 4 2001Kathleen E. Duncan Successful treatment of refinery spent-sulfidic caustic (which results from the addition of sodium hydroxide solutions to petroleum refinery waste streams) was achieved in a bioreactor containing an enrichment culture immobilized in organic polymer beads with embedded powdered activated carbon (Bio-Sep). The aerobic enrichment culture had previously been selected using a gas mixture of hydrogen sulfide and methyl mercaptan (MeSH) as the sole carbon and energy sources. The starting cultures for the enrichment consisted of several different Thiobacillispp. (T. thioparus, T. denitrificans, T. thiooxidans, and T.neopolitanus), as well as activated sludge from a refinery aerobic wastewater treatment system and sludge from an industrial anaerobic digester. Microscopic examination (light and SEM) of the beads and of microbial growth on the walls of the bioreactor revealed a great diversity of microorganisms. Further characterization was undertaken starting with culturable aerobic heterotrophic microorganisms (sequencing of PCR-amplified DNA coding for 16S rRNA, Gram staining) and by PCR amplification of DNA coding for 16S rRNA extracted directly from the cell mass, followed by the separation of the PCR products by DGGE (denaturing gradient gel electrophoresis). Eight prominent bands from the DGGE gel were sequenced and found to be closest to sequences of uncultured Cytophagales (3 bands),Gram-positive cocci (Micrococcineae), , proteobacteria (3 bands), and an unidentified , proteobacterium. Culturable microbes included several genera of fungi as well as various Gram-positive and Gram-negative heterotrophic bacteria not seen in techniques using direct DNA extraction. [source] | |||||||||||||||||||