THE INTERNATIONAL MARKET FOR FILTER MEDIA:
ITS CHARACTERISTICS, TRENDS AND DRIVERS
K. Sutherland (pages 196-200)
The place of nonwoven materials in the filter media marketplace requires definition of the marketplace, after which market size estimates are given – the estimating process, scope of estimates, and data for the global market are discussed. Media types are broken down to show the position of nonwoven materials. The geographical breakdown of global figures and their end uses and recent developments in the filter media market are evaluated. Market growth rates are discussed along with the driving forces, noting the special need for finer degrees of filtration, higher fluid temperatures, and environmental protection.
LAB PROTOCOL FOR A SPIN TUBE TEST, SIMULATING CENTRIFUGAL COMPACTION OF ACTIVATED SLUDGE
B. Peeters, L. Vernimmen and W. Meeusen (pages 201-213)
The spin tube test is a key bench scale test performed to simulate settling and compaction of activated sludge under centrifugal acceleration in a solid bowl decanter centrifuge. This test allows research of cake compactibility (cake dewaterability) under controlled laboratory conditions and has already shown its value; insights gained by executing the spin tube test on a regular basis allowed the optimization of an industrial centrifuge-dryer system at the Monsanto plant in Antwerp, Belgium.
This paper describes the formal Gauge R&R (repeatability and reproducibility) study that was executed at the beginning, before the test was introduced as a standard test. Since the spin tube test was a brand new test in the laboratory before intensive data collection could be started, it was necessary to ensure that the measurement system would not lead to erroneous conclusions. The paper starts with a short introduction of a Gauge R&R study. Next, the applied lab protocol of the spin tube test is described in detail. The results of the Gauge R&R study showed the spin tube test procedure to be consistent: the cake dryness results are repeatable for the individual analysts, and the dryness results between the analysts are reproducible. After the formal Gauge R&R, results of further lab exploration of the compaction mechanism are discussed. These additional results confirm indirectly the consistency of the spin tube test
A NEW MAGNETIC FILTER FOR SELECTIVE BIOSEPARATION
C. Eichholz, M. Stolarski and H. Nirschl (pages 213-218)
One of the emerging fields in the downstream processing of modern biotechnology lies in the use of particulate systems with functionalized surfaces to separate a target bioproduct like protein, enzyme, DNA etc. from bio-broth by selective adsorption. The application of magnetic separation methods has emerged for analytical purposes. In order to apply the same concept to industrial bioproduction processes new technologies have to be provided which allow effective and economical procedures. In this work a new magnetic filter for selective bioseparation is introduced. The principle is demonstrated by the recovery of pure lysozyme, but it can be extended to real biosuspensions in a similar manner.
CONDITIONING OF FILTER BAGS WITH REACTIVE CaO AND Ca(OH)2 DUST IN FLUE GAS
M. Koch, M. Saleem, P. Pucher and G. Krammer (pages 219-223)
Gas cleaning from reactive dusts is an issue in reactive flue gas cleaning processes. Changes in the specific dust volume due to reactions are especially challenging for filter media, leading to possible pore clogging and filter media blinding. A conditioning period of 120 h for two types of textile filter bags in a reactive atmosphere of artificial flue gas is simulated in an experimental setup at elevated temperature. The evolution of the filter cloth permeability and specific cake resistance are presented. In addition a novel method to determine apparent inhomogeneities of the filter media is applied. For all test series it is found that filtration is also possible in the long term. The final cloth permeability after conditioning is lower for CaO dust than for Ca(OH)2, and is higher than zero, and semi-continuous filter operation is possible with every investigated cloth – dust combination. It is found that even an almost new filter cloth exhibits distinctive spatial differences in permeability. The decrease of the mean permeability value is mainly attributed to a shift of this permeability profile, rather than homogeneous filter blinding.
A SIMULATION-BASED OPTIMIZATION APPROACH TO POLYMER EXTRUSION FILTER DESIGN
K.R. Fowler, E.W. Jenkins, S.M. LaLonde and C.L. Cox (pages 224-230)
In this work, we propose methods for evaluating filter performance and use these methods in an optimization framework to find parameters that maximize the lifetime of the filter while minimizing the amount of debris that escapes. We couple a three-dimensional computational tool that models the deposition process within the filter with optimization algorithms that use the output from the simulator to search the design space. This is a difficult problem that is not described by a differentiable function, since function evaluations are given by a ‘black-box’ simulator. We apply derivative-free techniques to analyze the behaviour of the filter and to gain insight into effective filter design. We discuss these techniques, along with our approaches to the mathematical formulation, and present numerical results and discuss future directions for this work.
MECHANICAL SENSORS FOR IDENTIFYING NANO/MICRO PARTICLES
D.W. Dareing and T. Thundat (pages 231-240)
Nanomechanics offer exciting opportunities for the development of novel sensors and imaging tools for nanotechnology. Many chemical and biological processes result in nanomechanical responses that can be measured with unprecedented sensitivity using microfabricated cantilever beams. Here, we describe nanomechanical tools for visualizing nanometre-sized materials and measuring and detecting nanomechanical forces. Static mode of operation of a microcantilever sensor to sense the presence of biological and chemical agents using forces involved in adsorption process, and a dynamic mode of detection of mass adsorption are addressed. The paper also explains how microcantilevers are used to measure gas and liquid viscosity, which may be used as a marker for the presence of biological and chemical agents. Condensation of vapours in porous structures such as charcoal results in capillary pressure-induced expansion that could be measured with a cantilever. This phenomenon can be used as a basis for developing simple sensors for chemicals.