Use of electrochemical oxidation process as post-treatment for the effluents of a UASB reactor treating cellulose pulp mill wastewater.

The main purpose of this study was to evaluate the performance of the electrochemical oxidation process as a post-treatment for the effluents of a bench-scale UASB reactor treating simulated wastewater from an unbleached pulp plant. The oxidation process was performed using a single compartment cell with two plates as electrodes. The anode was made of Ti/Ru0.3Ti0.7O2 and the cathode of stainless steel. The following variables were evaluated: current density (75, 150 and 225 mA cm(-2)) and recirculation flow rate in the electrochemical cell (0.22, 0.45 and 0.90 L h(-1)). The increase in current density from 75 to 225 mA cm(-2) did not increased the color removal efficiency for the tested flow rates, 0.22, 0.45 and 0.90 L h(-1), however the energy consumption increased significantly. The results indicated the technical feasibility of the electrochemical treatment as post-treatment for UASB reactors treating wastewaters from pulp and paper plants.     

A case study of regional catchment water quality modelling to identify pollution control requirements.

There are four ecologically important river catchments that contain candidate Special Areas of Conservation (cSACs) under the Habitats Directive in the Lake District National Park located in the North of England. These are the rivers Ehen, Kent, Derwent and Eden. For each cSAC, there are defined ecological criteria that include water quality targets to protect the designated species. Stretches of the riverine cSACs in each catchment are failing to meet these and other water quality targets. The Environment Agency commissioned a study of each catchment to provide the underpinning scientific knowledge to allow it to deliver its statutory obligations under the Habitats Directive. SIMCAT river water quality models were produced and used to predict the water quality impacts resulting from a number of water quality planning scenarios aimed at achieving full compliance with the Habitats Directive and other national and EEC water quality targets. The results indicated that further controls on effluent discharges will allow the majority of targets to be met but other sources of pollution will also need to be controlled. The outcome of the study also recognised that water quality improvements alone will not necessarily produce the required improvement to the ecological interest features in each cSAC.     

Disc filtration for separation of flocs from a moving bed bio-film reactor.

A Discfilter with 10 and 18 microm filter openings, respectively, was placed in parallel to a flotation plant for separation of biological flocs from a post-denitrifying Kaldnes Moving Bed Process, the last treatment step at the municipal wastewater treatment plant at Sj?unda, Malm?, Sweden. The effluent concentrations from the 10 and 18 microm filter were 2-5 and 2-8 mg SS L(-1), respectively, which is comparable to, or better than, the flotation plant. Comparison with experiences from activated sludge plants shows that the Discfilter works especially well after the Kaldnes process. Particle size distribution (PSD) studies show that particles larger than the filter openings of 10 and 18 microm are separated with approximately 90% efficiency, whereas most of the smaller particles pass the filter. This fact indicates that the major particle separation mechanism is physical blocking. These findings point to the possibility of improving the prediction of the separation efficiency by combining measurements of turbidity and suspended solids with particle size analysis.     

Threshold and growth mechanism of fatigue cracks under mode II and III loadings

ABSTRACT The fatigue crack growth behaviour of 0.47% carbon steel was studied under mode II and III loadings. Mode II fatigue crack growth tests were carried out using specially designed double cantilever (DC) type specimens in order to measure the mode II threshold stress intensity factor range, ΔK_IIth. The relationship ΔK_IIth > ΔK_Ith caused crack branching from mode II to I after a crack reached the mode II threshold. Torsion fatigue tests on circumferentially cracked specimens were carried out to study the mechanisms of both mode III crack growth and of the formation of the factory‐roof crack surface morphology. A change in microstructure occurred at a crack tip during crack growth in both mode II and mode III shear cracks. It is presumed that the crack growth mechanisms in mode II and in mode III are essentially the same. Detailed fractographic investigation showed that factory‐roofs were formed by crack branching into mode I. Crack branching started from small semi‐elliptical cracks nucleated by shear at the tip of the original circumferential crack.     

Structure and Certain Properties of Hot-Pressed Boron Carbide-Based Ceramic with Calcium-Silicon Additive

The influence which the composition of powder mixtures, the treatment conditions which the mixtures are subjected to, and the conditions under which the hot-pressed composite materials B₄C – (5-10 mass%) calcium-silicon are fabricated exert on the structure, nature of failure, and mechanical properties of these materials is investigated. Optimum properties are possessed by material containing 10 mass% of addition. It is shown that the structure, morphology, and dispersivity, as well as the nature of the distribution of the components that are added to the composite material (secondary phase) vary as the temperature of hot pressing changes. Maximal mechanical characteristics of the composite material (σ_bend = 560 MPa, K _1c = 4.7 MPa·m^1/2, HV = 37 GPa) are attained at hot-pressing temperatures in the range 2000-2100°C.     

Thermal storage efficiencies of two solar saltless water ponds

A comparative study between two types of solar ponds is presented. The first type has its free surface covered by a thin layer of transparent paraffin oil. The second type is covered by transparent glass floating devices. Each device disposes an air-vacuum chamber. The free water surface between these devices is covered by transparent paraffin oil also. The thermal storage efficiency of each pond is estimated during two time periods: between sunrise and sunset and from midnight to midnight. The calculated efficiency between sunrise and sunset corresponds to the average transmittance–absorptance product. This is estimated using linear regression and also a maximum likelihood identification technique. The behavior of the system was studied by solving numerically the heat transfer equations of the system. Also an ARMAX (AutoRegressivie Moving Average with eXogenous signal) model allowing the assessment of its performance was presented. This efficiency is larger for the first pond during the sunrise to sunset period and smaller when calculated from midnight to midnight. Thus, the first type of pond could be preferred for a use just after the sunset of the same day, while the second for use after one or more days of heat storage.     

Combined time and wavelength multiplexing technique of optical fiber grating sensor arrays using commercial OTDR equipment

The use of a commercial optical time domain reflectometry device for simultaneous wavelength and time domain multiplexing of fiber-optic Bragg grating sensors is proposed and demonstrated. The realization of such systems provides an inexpensive way of interrogating several hundreds of sensors in a single fiber. Strain resolution of 30 /spl mu/m/m over a strain measuring range of 0.5% was obtained.     

One-dimensional diffuser based on a thick layer of dichromated gelatin

A new diffuser capable of scattering light in one direction (one-dimensional diffuser) has been developed and experimentally tested. The diffuser is formed in a thick layer of dichromated gelatin. The scattering indicatrices of the diffuser measured in two mutually perpendicular directions are presented. It is demonstrated that the indicatrix width in one direction is significantly greater than that in the perpendicular direc-tion. However, no zero-order diffraction has been observed. The proposed one-dimensional diffuser exhibits close scattering indicatrices for reading at a wavelength of 0.44 and 0.63 μm.     

British female academics and comparative psychology: Attempts to establish a research niche in the early 20th century.

Why was there a preponderance of women engaged in laboratory-based studies of animal behavior in Britain in the early years of the 20th century? As a new experimental subject with recently neglected potential, animal psychology then represented an opportunity for women to make further inroads into academic science. Because the study of psychology before World War I offered negligible professional opportunities for the application of the subject, the intake of students was restricted. Perhaps this encouraged academic access to it by aspiring female scientists who felt that career prospects, uncertain and socially unexpected of them in any case, were worth chancing for greater long-term rewards. The academic circumstances and contributions of 3 British female pioneers in experimental comparative psychology are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)