Behaviour of chlorophenoxy herbicides during the activated sludge treatment of municipal waste water

The potential of the activated sludge treatment process for the removal of chlorophenoxy herbicides (CPH) from domestic waste water has been investigated. A series of laboratory jar tests and pilot plant experiments were performed using real settled sewage fortified with 10 μl⁻¹ of each of six CPH. The experiments were designed with the objective of assigning any CPH removal which might occur to a particular removal mechanism. In particular, the effect of varying the sludge age between each pilot plant experiment was studied, in view of the importance of sludge age in determining the biodegradative potential of activated sludge.Generally, activated sludge treatment proved ineffective in removing CPH contaminants from settled sewage. Statistical treatment of the data suggested that neither adsorption nor catabolic biodegradation were responsible for those significant CPH removals that did occur. Indeed, there was no evidence of acclimatization of the mixed liquor to the presence of CPH contaminants. Furthermore, there was no obvious effect of sludge age on the efficiency of CPH removal from settled sewage. However, the extent and pattern of substitution of CPH appeared to be important in determining the efficiency of CPH removal, which implies that a biological mechanism was involved. The likelihood that co-metabolism was responsible for CPH removal has been considered.The possible implications of poor CPH removal by activated sludge treatment have been discussed, with reference to the relevant EEC legislation.     

Determining the extent of biodegradation of fuels using the diastereomers of acyclic isoprenoids

Improved testing and remediation procedures for sites contaminated with petroleum hydrocarbons are a priority in remote cold regions such as Antarctica, where costs are higher and remediation times are longer. Isoprenoid/n-alkane ratios are commonly used to determine the extent of biodegradation at low levels but are not useful once the n-alkanes have been removed. This study demonstrates how the diastereomers of the acyclic isoprenoids can be used to determine the extent of biodegradation in moderately biodegraded fuel in soils from a bioremediation trial at Casey Station, Antarctica. The biological diastereomers of pristane (meso; RS = SR) are depleted more rapidly during moderate biodegradation than the geological or mature diastereomers (RR and SS), and thus, the ratio of pristane diastereomers can determine the level of biodegradation. The statistical difference among mean diastereomer ratios for samples grouped according to the biodegradation scale and pristane/phytane ratios was highly significant. The ratios of norpristane and phytane diastereomers also change with biodegradation in a similar fashion, and different levels of sensitivity exist for each. Additional benefits are that the method can be performed on conventional gas chromatographs by non-specialist chemists and that the ratios are independent of evaporation and do not necessarily require a non-biodegraded reference (T0) sample. This study details a simple alternative method for determining the extent of biodegradation of fuels at moderate levels that can be applied to a wide range of petroleum products.     

Control of Listeria monocytogenes growth in a ready-to-eat poultry product using a bacteriophage

A bacteriophage (phage) that infected strains of the species Listeria monocytogenes as well as Listeria ivanovii and Listeria welshimeri, but not Listeria grayi or Listeria innocua, was isolated from sheep faeces. The phage had a contractile tail and an icosohedral head indicating that it was a myovirus, and was morphologically similar to phage A511. At 30 °C, phages added at 5.2 × 10⁷ PFU ml⁻¹ prevented the growth in broth of L. monocytogenes present at approximately twice this concentration for 7 h, but re-growth occurred such that the concentration after 24 h incubation was similar in both control and phage-treated cultures. At the same temperature, but on the surface of vacuum-packed ready-to-eat chicken breast roll, there was an immediate 2.5 log₁₀ CFU cm⁻² reduction in pathogen concentration following addition of phages and then re-growth. However, at a temperature reflecting that at which a chilled food might be held (5°C), this re-growth was prevented over 21 days incubation. The data suggest a dose-dependent rapid reduction in pathogen concentration followed by no continued phage-mediated effect. These results, alongside other published data, indicate that a high concentration of phages per unit area is required to ensure significant inactivation of target pathogens on food surfaces.     

Atomic layer-deposited tunnel oxide stabilizes silicon photoanodes for water oxidation

A leading approach for large-scale electrochemical energy production with minimal global-warming gas emission is to use a renewable source of electricity, such as solar energy, to oxidize water, providing the abundant source of electrons needed in fuel synthesis. We report corrosion-resistant, nanocomposite anodes for the oxidation of water required to produce renewable fuels. Silicon, an earth-abundant element and an efficient photovoltaic material, is protected by atomic layer deposition (ALD) of a highly uniform, 2 nm thick layer of titanium dioxide (TiO(2)) and then coated with an optically transmitting layer of a known catalyst (3 nm iridium). Photoelectrochemical water oxidation was observed to occur below the reversible potential whereas dark electrochemical water oxidation was found to have low-to-moderate overpotentials at all pH values, resulting in an inferred photovoltage of ~550 mV. Water oxidation is sustained at these anodes for many hours in harsh pH and oxidative environments whereas comparable silicon anodes without the TiO(2) coating quickly fail. The desirable electrochemical efficiency and corrosion resistance of these anodes is made possible by the low electron-tunnelling resistance (<0.006 Ω cm(2) for p(+)-Si) and uniform thickness of atomic-layer deposited TiO(2).     

In the eyes of the beholder: A non-self-report measure of workplace deviance.

Because employees may be reluctant to admit to performing deviant acts, the authors of this study reexamined the commonly used self-report measure of workplace deviance developed by R. J. Bennett and S. L. Robinson (2000). Specifically, the self-report measure was modified into a non-self-report measure based on multiple other-reported assessments to address methodological concerns with self-reported information regarding deviant workplace behaviors. The authors assessed the psychometric properties of this new measure by first conducting an exploratory factor analysis, which indicated a 3-factor structure (production deviance, property deviance, and personal aggression). Subsequent confirmatory factor analysis on a different sample verified these findings. Taken together, the results suggest that the content and psychometric qualities of this non-self-report measure of workplace deviance closely represent S. L. Robinson and R. J. Bennett's (1995) original typology of workplace deviance. The potential usefulness of this measure in organizational studies is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)