Yolanda Fernandez

REMOVAL OF COPPER AND CADMIUM IONS FROM DILUTED AQUEOUS SOLUTIONS BY LOW COST AND WASTE MATERIAL ADSORBENTS

The sorption of copper and cadmium ions using activated carbon,kaolin, bentonite, diatomite and waste materials such as compost,cellulose pulp waste and anaerobic sludge as sorbents is reported. Equilibrium isotherms were obtained for the adsorption of these metals in single and binary solutions. Bentonite presented the highest adsorption capacities for both copper and cadmium. A competitive uptake was observed when both metals are present; copper being preferentially adsorbed by all materials with theexception of anaerobic sludge. Equilibrium data were fitted toLangmuir and Freundlich models, with satisfactory results for most of the adsorbent-metal systems studied.Of all the adsorbents studied, bentonite and compost presentedthe highest removal efficiencies, reaching 99% for copper whencadmium is also present, for initial solution concentrations ofup to 100 mg L-1. Anaerobic sludge has a greater preferencefor cadmium, even in the presence of copper, with removal efficiencies of 98% for similar concentrations to those mentioned above.

Anaerobic mesophilic treatment of cattle manure in an upflow anaerobic sludge blanket reactor with prior pasteurization

Abstract Different autonomous communities located in northern Spain have large populations of dairy cattle. In the case of Asturias, the greatest concentration of dairy farms is found in the areas near the coast, where the elimination of cattle manure by means of its use as a fertilizer may lead to environmental problems. The aim of the present research work was to study the anaerobic treatment of the liquid fraction of cattle manure at mesophilic temperature using an upflow anaerobic sludge blanket (UASB) reactor combined with a settler after a pasteurization process at 70 °C for 2 hr. The manure used in this study came from two different farms, with 40 and 200 cows, respectively. The manure from the smaller farm was pretreated in the laboratory by filtration through a 1-mm mesh, and the manure from the other farm was pretreated on the farm by filtration through a separator screw press (0.5-mm mesh). The pasteurization process removed the pathogenic microorganisms lacking spores, such as Enterococcus, Yersinia, Pseudomonas, and coliforms, but bacterial spores are only reduced by this treatment, not removed. The combination of a UASB reactor and a settler proved to be effective for the treatment of cattle manure. In spite of the variation in the organic loading rate and total solids in the influent during the experiment, the chemical oxygen demand (COD) of the effluent from the settler remained relatively constant, obtaining reductions in the COD of ∼85%.

Thickness quality control

This article describes a series of methods to detect thickness defects in DWI tinplate. These methods provide information to identify the origin of the defects, allowing fast corrections and, therefore, improving mill performance. In this approach, an adapted thickness signal is spatially sampled from the input stages of the mills last X-ray gauge. The system is also able to detect other problems related to thickness quality such as third-octave chatter using only the thickness measures from an X-ray gauge. The usage of this system resulted in an improvement in the factory performance and considerable money savings.

Conoscopic holography based profilometers for defect inspection : improvements in speed, resolution and noise reduction

One of the more challenging applications of optical metrology is real-time dimensional control and surface inspection in industrial applications, where strong requirements of cost, speed of operation, ease of setup and applicability in adverse environments, greatly limit the number of applicable technologies. An optic profilometer, based on Conoscopic holography, has been designed specifically for this purpose and used in several on-line inspection systems. This device is able to obtain a distance profile of a target in a single shot; works at long distance standoff (700-1200mm) and still keeps good resolution (under 0.2mm) with a very easy and reliable setup. However, there are still some drawbacks that should be addressed. The first one is the signal processing, which is a relatively expensive process and limits the acquisition rate at no more than 70 profiles per second. The second one is speckle noise, which is an inherent problem in systems that use coherent-light illumination and triangulation, and therefor could be extrapolated to many other optical inspection systems. This paper shows the current lines of research to solve both problems and presents some initial, yet very interesting, results. These improvements can be applicable to other ranges of devices using this technology in adverse environments, for roughness and vibration measurement or surface defects detection.

On-line wavy strip and off-center analysis of high speed production lines by a linear camera

This paper describes a method for analyzing undulation and off-center of a flat product in a web inspection by a linear camera. The longitudinal undulation in the plate appears to the high speed of the line and different tensions across the strip section as it is pulled to the end of the line. If the amplitude and/or frequency of the undulation is too high it will produce an increase of breakage probability and new defects may appear. In addition, it introduces errors in width measurement if it is not taken into account. We propose a method to identify undulation characteristics based on time-frequency analysis of the projection of the strip edge. We recover the position of the edge and undulation by assuming that band off-center is a slower process than undulation. Simulations with different undulation waveforms and off-centers, as well as experimental results are shown.

Improving signal processing performance on a conoscopic holography-based profilometer with phase-shifting interferometry algorithms

One of the more challenging applications of optical metrology is real-time dimensional control and surface inspection in industrial applications, where strong requirements of cost, speed of operation, ease of setup and applicability in adverse environments greatly limit the number of applicable technologies. The design and uses of an optic profilometer, based on conoscopic holography, have been reported previously, but there are still some drawbacks that should be addressed. One of the most important is signal processing, which is a relatively expensive process and limits the acquisition rate at no more than 70 profiles per s. We present a new approach to the signal processing problem, deriving that the phase information contained in one fringe pattern, which corresponds to one profile, can be considered as a combination of multiple one-dimensional (1-D) patterns that carry the same information but for a phase difference in the carrier wave, making it possible to apply efficient phase-shifting interferometry (PSI) techniques and resulting in a reduction of more than two orders of magnitude in computational needs.

A long standoff profilometer for surface inspection in adverse environments based on conoscopic holography

One of the more challenging applications of optical metrology is real-time dimensional control and surface inspection in industrial applications, where strong requirements of cost, setup and applicability in adverse environments, greatly limit the number of applicable technologies. This paper shows an optic profilometer developed specifically for this purpose. This device, based on Conoscopic holography, is able to obtain a distance profile of a target in a single-axis scan; works from long distances and still keeps good resolution with a very easy and reliable setup. The first part of the paper introduces the working principles of Conoscopic holography and shows the sensor set-up. Necessary algorithms for obtaining the distance information are presented and the whole process is illustrated with real captures of test objects. The second part focuses on a real example of this technology applied in an on-line inspection system in steel continuous casting funded by the European Committee for Steel and Carbon, and which is currently working in Aceralia LDA steelmaking factory in Asturias (Spain). The system is placed in the process line and performs on-line detection of surface defects over hot steel slabs from a distance of 1200 mm. 100% of the production can be inspected without interfering with the process and without adding any delay.

Thickness quality control and diagnosis system for tinplate rolling mills

The draw wall ironed (DWI) tinplate market clearly trends to demand a reduction in thickness, which implies stricter tolerance levels as small variations could result in problems in the manufacturing process and therefore customers dissatisfaction in a highly competitive market. This paper describes a series of methods to detect thickness defects in DWI tinplate. In addition, these methods provide information to identify the origin of the defects, allowing fast corrections and therefore improving mill performance. In our approach an adapted thickness signal is spatially sampled from the input stages of the mills last X-ray gauge.

Denoising of conoscopic holography fringe patterns with orientational filters: a comparative study

One of the most important problems to address when applying interferometric techniques to industrial applications is the high presence of noise which results in poor fringe patterns and thus poor measurements. One of the techniques that suffers most with this problem is conoscopic holography. Even if this interferometric technique is ideal for industrial inspection, the poor quality of fringe patterns obtained in adverse environments may even make measurement impossible. Classical filtering techniques based on one-dimensional filters or general speckle removal filters such as Frost or Gamma may not suffice in adverse conditions, therefore a new approach based on the nature of the fringe pattern information itself must be looked into. In this paper we propose the use of orientational filters to develop a filtering method, that not only removes noise of any nature, but also enhances the fringe pattern information. Several approaches to these algorithms are implemented and evaluated using synthetic conoscopic fringe patterns under different noise conditions, showing how they clearly outperform classical filters with a negligible distortion even in the worst conditions. Examples with real data acquired with the latest prototype of conoscopic long-standoff profilometer are also provided.