Removal of zeolite type a during primary sedimentation and its effect on metal removal

Using two pilot plants operated in parallel, treating settled sewage the removal of the detergent builder zeolite type A during primary sedimentation has been studied. With one zeolite free pilot plant acting as a control to the other it was also possible to determine the effect of zeolite on suspended solids and heavy metal removal over a range of hydraulic loadings. At both influent concentrations of zeolite studied (30 and 60 mg l⁻¹) zeolite removal was substantial under all conditions. No evidence of enhanced removal of suspended solids in the presence of zeolite was observed. Removals of lead, zinc, copper and chromium were slightly enhanced in some experiments. The observed improvements in metal removal appeared to be strongly influenced by the sewage matrix.     

Role of bacterial extracellular polymers in metal uptake in pure bacterial culture and activated sludge—I. Effects of metal concentration

A gel filtration technique afforded a good separation between metal complexed with bacterial extracellular polymers and free metal ions. The complexation of polymers extracted from cultures of Klehsiella aerogenes and activated sludge with cadmium, nickel, manganese and cobalt was demonstrated. The extraction of extracellular polymers from cultures of K. aerogenes and activated sludge reduced the capacity of the cells and flocs to adsorb metal. Adsorption and complexation of metals by cells of K. aerogenes and extracellular polymers extracted from activated sludge were fitted to Freundlich equilibrium isotherms. Saturation of activated sludge polymer binding sites occurred at 10 mg 1^?1 metal additions for all the metals studied except manganese which was complexed to a very limited extent. Cells of K. aerogenes exhibited no saturation effects in the range of metal concentrations studied.Precipitation of metals below a concentration of 1 mg 1^?1 was minimal, with the exception of cadmium precipitation. At a concentration of 10 mg 1^?1, precipitation of cadmium, cobalt and manganese may have been the major mechanism of metal removal. The more soluble metals generally displayed the lowest removals. Concentrations of extracellular polymers and soluble chelating agents may be important in controlling removals of metals which are largely soluble in activated sludge.     

Transmission Electron Microscopy-Based Analysis of Electrically Conductive Surface Defects in Large Area GaSb Homoepitaxial Diodes Grown Using Molecular Beam Epitaxy

We investigate a mechanism causing shorting of large area GaSb diodes grown on GaSb substrates using molecular beam epitaxy (MBE). The source of these shorts is determined to be large crystallographic defects on the surface of the diodes that are formed around droplets of gallium ejected from the gallium Knudsen cells during MBE. The gallium droplets cause defects in the crystal structure, and, as the epitaxy continues, the gallium is incorporated into the surrounding material. The shape of the defects is pyramidal with a central void extending from the epi-surface to the gallium core. Processing a GaSb diode with these surface defects results in the top-side contact metal migrating into the defect and shorting the diode. This prevents realization of large area diodes that are critical to applications such as photovoltaics and detectors. The diodes in this study are electrically characterized and the defect formation mechanism is investigated using cross-section transmission electron microscopy and electron dispersive spectroscopy.     

On rating empathy and other psychotherapy variables: An experience with the effects of training.

Compared 3 methods of assessing the psychotherapist's empathy: (a) the Accurate Empathy Scale, (b) the Conjunctive Empathy Scale, and (c) the Raskin Empathy Scale. 5 moderately to very experienced judges rated 10 4-min segments of a tape-recorded psychotherapy session during pre- and posttraining phases. The mean reliability of the 3 scales increased significantly, and intercorrelations were nearly perfect when corrected for unreliability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perennial mystery of poor agreement among criteria for psychotherapy outcome.

Discusses S. Garfield, R. Prager, and A. Bergin's (see pa, vol. 47:issue 5) finding of little relationship among criteria and most change on global ratings of improvement which they believe are the most biased. Values of the global improvement ratings are discussed. Patient and therapist (and supervisor) have intimate knowledge of the specific areas needing change; many other measures are nonspecific or insensitive to change, and since therapeutic gains may be small, intercorrelations among criteria may be limited. Some of the statistics are questioned: raw gain scores are of questionable value; the relative importance of changes on the "other measures" is unclear; and considering the unreliability of single item ratings, the amount of the interrelationship among different criteria is not to be dismissed as slight. Furthermore, rotation of their factor matrix showed patient, therapist, and supervisor ratings of change loading the same factor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Telemetered heart rate and skin potential of a chronic schizophrenic patient especially during periods of hallucinations and periods of talking.

Took telemetric recordings of a male 23-yr-old chronic schizophrenic patient's heart rate and skin potential while on the ward. During periods of hallucinations, the skin potential increased significantly, while there were no changes in heart rate. Neither heart rate nor skin potential increased during periods of talking. When very angry, heart rate showed a substantial deceleration followed by a large increase. There was no change in skin potential during the period of anger. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Environmental aspects of the use of NTA as a detergent builder

The behaviour, fate and significance of the detergent builder nitrilotriacetic acid (NTA) has been reviewed with particular reference to the removal of NTA during wastewater treatment and the effects of NTA on heavy metal solubility both during treatment and in the receiving environment. It is concluded that NTA removal during secondary biological treatment is subject to considerable variation, both temporal and between works as a result of changes in NTA load, temperature, water hardness and treatment process parameters. As a result of such variability, effluent NTA concentrations may be sufficient to mobilise heavy metals resulting in metal contamination of receiving waters and potable waters, particularly in areas of low effluent dilution and high water re-use. Removal of NTA during primary sedimentation and septic tank treatment is concluded to be predominantly due to adsorption to the sludge solids while removal in anaerobic sludge digestion is subject to operational characteristics of the treatment works. Disposal of NTA contaminated sludge to land may contaminate groundwaters and affect heavy metal speciation, while the disposal of contaminated sludge or sewage to sea may result in toxic algal blooms, in addition to effects on metal speciation.