Neustonic versus epiphytic bacteria of eutrophic lake and their biodegradation ability on deltamethrin

This study evaluated biodegradation of the insecticide deltamethrin (1 μg l−1) by pure cultures of neustonic (n = 25) and epiphytic (n = 25) bacteria and by mixed cultures (n = 1), which consisted of a mixture of 25 bacterial strains isolated from the surface microlayer (SM ≈ 250 μm) and epidermis of the Common Reed (Phragmites australis, (Cav.) Trin. ex Steud.) growing in the littoral zone of eutrophic lake Chełmżyńskie. Results indicate that neustonic and epiphytic bacteria are characterized by a similar average capacity to degrade deltamethrin. After a 15-day incubation, bacteria isolated from the surface microlayer reduced the initial concentration of deltamethrin by 60%, while the average effectiveness of the bacteria found on the Common Reed equaled 47%

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Is Adsorption an artefact in experimentation with triclosan?

This paper examines the effect of adsorption of Triclosan (TCS) onto labware on the results obtained during lab-scale experiments. Three sets of experiments were considered; two of them expose the problem in water or wastewater treatability studies and the other one in microbial susceptibility testings. In the former two sets, lab-scale systems; ozonation; and membrane filtration (NF/RO) that are commonly used in water or wastewater treatability studies were utilized and the distribution of TCS within the systems were followed. The ozonation labware tested was composed of a Pyrex reactor with plastic and glass tubings. The NF/RO system was composed of a stainless steel feed tank, a stainless steel membrane unit, stainless steel flanges, and stainless steel and plastic tubings. Ozonation system was operated without ozone gas, but air. Similarly, NF/RO system was without membrane in it. Both of the systems were rinsed with methanol before experiments to remove any possible earlier contamination. During the experiments, samples were taken at certain intervals and the change in TCS concentration in water was monitored. Results obtained with lab-scale ozonation system revealed that TCS adsorbed by the surface of plastic tubing is about 100 times greater than that of glass tubing. In NF/RO system, the higher the initial TCS concentration the higher the mass of TCS adsorbed by the membrane filtration system alone was evident. In the third set, microbial susceptibility testing was conducted on Staphylococcus aureus for TCS and the possible effect of adsorption of TCS onto the plastic labware was sought by comparing MIC and MBC values performed by serial dilutions in aqueous and methanol solutions. MIC and MBC values determined using TCS in methanol range from 0.06 to 16 mg/L, while the ones determined with TCS in water range from 0.25 to 128 mg/L. All the results obtained indicated that adsorption is a substantial phenomenon; in the event that it is not considered, obtained results might not reflect the truth. TCS was found to adsorb seriously on plastic but not on glass labwares. Therefore, before an experimental system that will employ TCS is designed, it is essential to consider the possible adsorption onto the experimental system components and to demonstrate that there is no adsorption of TCS onto labware

Effects of Trace Levels of Copper, Chromium, and Zinc Ions on the Performance of Activated Sludge

The effects of copper, chromium, and zinc ions, at trace levels, on the performance of a simulated activated sludge process were investigated. The results of batch adsorption experiments showed that the adsorption of copper, chromium, and zinc ions followed both the Langmuir and Freundlich isotherms. The presence of trace levels of these three metals not only reduced the adsorption rate of organic matters but also the chemical oxygen demand adsorption capacity (CAC) of the activated sludge. Metal ions competed with the organic substrate for adsorption binding sites on the surfaces of activated sludge bioflocs and reduced the CAC. Studies performed in a sequential batch reactor (SBR) showed that the presence of trace levels of heavy metal ions in wastewater affected the SBR performance to different extents depending on the hydraulic retention time (HRT). When the reactors were operated at short HRTs of 2.5 d or less, the presence of trace levels of heavy metal ions reduced substantially the CAC of activated sludge, which, in turn, affected significantly the performance of the SBR. However, under longer HRTs (e.g., 5d), the heavy metal ions in the wastewater reduced the CAC but had no significant effect on the chemical oxygen demand removal efficiency.Department of Applied Biology and Chemical TechnologyDepartment of Civil and Environmental Engineerin