2,095 research outputs found

    Process for purification of waste water produced by a Kraft process pulp and paper mill

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    The water from paper and pulp wastes obtained from a mill using the Kraft process is purified by precipitating lignins and lignin derivatives from the waste stream with quaternary ammonium compounds, removing other impurities by activated carbon produced from the cellulosic components of the water, and then separating the water from the precipitate and solids. The activated carbon also acts as an aid to the separation of the water and solids. If recovery of lignins is also desired, then the precipitate containing the lignins and quaternary ammonium compounds is dissolved in methanol. Upon acidification, the lignin is precipitated from the solution. The methanol and quaternary ammonium compound are recovered for reuse from the remainder

    Exposure of ciprofloxacin-resistant Escherichia coli broiler isolates to subinhibitory concentrations of a quaternary ammonium compound does not increase antibiotic resistance gene transfer

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    Resistance to antibiotics threatens to become a worldwide health problem. An important attributing phenomenon in this context is that pathogens can acquire antibiotic resistance genes through conjugative transfer of plasmids. To prevent bacterial infections in agricultural settings, the use of veterinary hygiene products, such as disinfectants, has gained popularity and questions have been raised about their contribution to such spreading of antibiotic resistance. Therefore, this study investigated the effect of subinhibitory concentrations of benzalkoniumchloride (BKC), a quaternary ammonium compound (QAC), on the conjugative transfer of antibiotic resistance genes. Five Escherichia coli field strains originating from broiler chickens and with known transferable plasmid-mediated ciprofloxacin resistance were exposed to subinhibitory BKC concentrations: 1/3, 1/10 and 1/30 of the minimum bactericidal concentration. Antibiotic resistance transfer was assessed by liquid mating for 4 h at 25 degrees C using E. coli K12 MG1655 as recipient strain. The transfer ratio was calculated as the number of transconjugants divided by the number of recipients. Without exposure to BKC, the strains showed a ciprofloxacin resistance transfer ratio ranging from 10(-4) to 10(-7). No significant effect of exposure to subinhibitory concentrations of BKC was observed on this transfer ratio


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    Several green innovations are introduced in this memoir: (a) the steel plant' iron oxide solid waste particles can be reused efficiently as a weighing agent as well as a polarization-inducing agent in a magnetic field enhanced gravity sludge thickening process; (b) quaternary ammonium compound (cationic surfactant) is an excellent organic disinfectant for sludge (biosolids) stabilization and thickener supernatant disinfection; the thickener supernatant total coliform count was reduced from 100,000,000/100 mL to 160/100 mL; the stablized biosolids met the criteria of Class A Biosolids which will be available for agricultural applications; (c) a new sludge (biosolids) stabilization process involving the use of organic disinfectant has been developed; (d) quaternary ammonium compound (cationic surfactant) is an excellent flocculant for waste clarification and sludge thickening; (e) an innovative magnetic sludge thickening process involving the use of both iron oxide particles (as weighing and polarization-inducing agent) and quaternary ammonium compound (as disinfecting and flocculating agent) has been developed; (f) the innovative sludge stabilization process and magnetic sludge thickening process are feasible for thickening both biological biosolids and chemical sludges; This memoir is a "call for research" inviting environmental researchers to investigate the proposed green innovations further

    Genetic subtyping, biofilm-forming ability and biocide susceptibility of Listeria monocytogenes strains isolated from a ready-to-eat food industry

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    Research Areas: Infectious Diseases ; Pharmacology & PharmacyListeria monocytogenes is a foodborne pathogen of special concern for ready-to-eat food producers. The control of its presence is a critical step in which food-grade sanitizers play an essential role. L. monocytogenes is believed to persist in food processing environments in biofilms, exhibiting less susceptibility to sanitizers than planktonic cells. This study aimed to test the susceptibility of L. monocytogenes in planktonic culture and biofilm to three commercial food-grade sanitizers and to benzalkonium chloride; together with the genetic subtyping of the isolates. L. monocytogenes isolates were collected from raw materials, final products and food-contact surfaces during a 6-year period from a ready-to-eat meat-producing food industry and genetically characterized. Serogrouping and pulsed-field gel electrophoresis (PFGE) revealed genetic variability and di erentiated L. monocytogenes isolates in three clusters. The biofilm-forming ability assay revealed that the isolates were weak biofilm producers. L. monocytogenes strains were susceptible both in the planktonic and biofilm form to oxidizing and ethanol-based compounds and to benzalkonium chloride, but not to quaternary ammonium compound. A positive association of biofilm-forming ability and LD90 values for quaternary ammonium compound and benzalkonium chloride was found. This study highlights the need for preventive measures improvement and for a conscious selection and use of sanitizers in food-related environments to control Listeria monocytogenes.info:eu-repo/semantics/publishedVersio

    Limited association between disinfectant use and either antibiotic or disinfectant susceptibility of Escherichia coli in both poultry and pig husbandry

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    Background Farm disinfectants are widely used in primary production, but questions have been raised if their use can select for antimicrobial resistance. The present study examined the use of disinfectants in poultry and pig husbandry and its contribution to the antibiotic and disinfectant susceptibility of Escherichia coli (E. coli) strains obtained after cleaning and disinfection. On those field isolates antibiotic susceptibility was monitored and susceptibility to commonly used active components of farm disinfectants (i.e. glutaraldehyde, benzalkoniumchloride, formaldehyde, and a formulation of peracetic acid and hydrogen peroxide) was tested. Results This study showed a high resistance prevalence (> 50%) for ampicillin, sulfamethoxazole, trimethoprim and tetracycline for both production animal categories, while for ciprofloxacin only a high resistance prevalence was found in broiler houses. Disinfectant susceptibility results were homogenously distributed within a very small concentration range. Furthermore, all E. coli strains were susceptible to in-use concentrations of formaldehyde, benzalkoniumchloride and a formulation of peracetic acid and hydrogen peroxide, indicating that the practical use of disinfectants did not select for disinfectant resistance. Moreover, the results showed no indications for the selection of antibiotic resistant bacteria through the use of disinfectants in agricultural environments. Conclusion Our study suggests that the proper use of disinfectants in agricultural environments does not promote antibiotic resistance nor reduce E. coli disinfectant susceptibility

    Cathodic electrocatalyst layer for electrochemical generation of hydrogen peroxide

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    A cathodic gas diffusion electrode for the electrochemical production of aqueous hydrogen peroxide solutions. The cathodic gas diffusion electrode comprises an electrically conductive gas diffusion substrate and a cathodic electrocatalyst layer supported on the gas diffusion substrate. A novel cathodic electrocatalyst layer comprises a cathodic electrocatalyst, a substantially water-insoluble quaternary ammonium compound, a fluorocarbon polymer hydrophobic agent and binder, and a perfluoronated sulphonic acid polymer. An electrochemical cell using the novel cathodic electrocatalyst layer has been shown to produce an aqueous solution having between 8 and 14 weight percent hydrogen peroxide. Furthermore, such electrochemical cells have shown stable production of hydrogen peroxide solutions over 1000 hours of operation including numerous system shutdowns

    Cleaning and Disinfection of Caged Layer Facilities

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    A rapid and effective means to clean and disinfect affected premises is needed by the poultry industry. Commercially available foaming disinfectants and cleaners applied via a compressed air foam system (CAFS) may be used to significantly reduce aerobic bacteria in a commercial caged layer complex. Using a variety of agricultural products against bacterial species may also provide information on which products are most efficacious against specific microorganisms on cage floors. In the first study, six field trials were conducted to evaluate current industry cleaning and disinfection protocols and the proposed CAFS application. A commercially available chlorinated alkaline cleaner (CHL/ALK) in trials 1 & 2 was applied by CAFS to one half of the house, and the other half of the house was not treated. The entire house was then washed with a high pressure water rinse (HPWR). A commercially available peroxyacetic acid (PAA) in trials 3 & 4 or a 14% glutaraldehyde (HI GLUT)/2.5% quaternary ammonia (QAC) blended disinfectant in trials 5 & 6 was applied by CAFS to one half of a washed house. The remainder of each house was treated with 7% (LO GLUT)/26% QAC, which was the spray application applied to cages by the integrator. Environmental swabs of drinker cups and cage floors were collected pre and post treatment to determine if aerobic bacteria levels were reduced. The HPWR and the CHL/ALK treatments did not consistently reduce aerobic bacteria on treated surfaces. Significant differences were observed with each of the CAFS applications of the PAA, HI GLUT/QAC, and LO GLUT/QAC product. The objective of the second study was to determine the efficacy of commonly used products on soiled layer cages. Trial one was conducted in a small layer barn at the Texas A&M University Poultry Science Research, Teaching, and Extension Center. Trial two was performed at a commercial pullet house. In each trial, treatments were applied by a garden sprayer and six samples per treatment were collected. All products were mixed according to the manufacturer’s recommendations. Treatments consisted of a negative control, a low pressure water rinse (LPWR, garden hose), a high pressure water rinse (HPWR, pressure washer), a soap, a chlorinated alkaline cleaner, a QAC, a glutaraldehyde, a peroxyacetic acid, a phenolic, a potassium peroxymonosulfate, a hydrogen peroxide, and a QAC/glutaraldehyde blend product. Swabs of cage floors were collected post treatment to determine if bacterial loads were reduced as compared to the appropriate controls. Aerobic bacteria, coliforms, Staphylococcus spp., and Pseudomonas ssp. were enumerated to evaluate the efficacy of the treatments. Aerobic bacterial colonization was significantly reduced by the oxidizer, peroxyacetic acid, aldehyde, and QAC disinfectants in trial one and by all seven disinfectants in trial two against the HPWR control. No treatment, in the first trial, significantly decreased coliforms or Staphylococcus spp. when compared to controls of nothing and the HPWR. However, reduction (P < 0.05) of coliforms and Staphylococcus spp. were observed with all disinfectants in trial two. The aldehyde and QAT disinfectant products in trial one, and all disinfectant products except the hydrogen peroxide and QAT/glutaraldehyde compound in trial two significantly reduced the levels of Pseudomonas spp. These data suggest that characteristics of cleaning and disinfection regimens can vary significantly
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