Smart membrane f i l ters Researchers at the Sandia National Laboratory (SNL), in New Mexico, USA are using the technique of molecular self- assembly to develop novel mem- brane materials. Rather than manipulating atoms and molecules in to place as in nor- mal chemical synthesis, in self- assembly they arrange themselves in to place. This technique is opening up the possibility of manufacturing highly selective membranes or even smart mem- branes that use nanomachines to open and close their pores according to the identity of molecules approaching them. Jeff Brinder from SNL, a pioneer of self-assembly research, has recently produced an ultra-thin coating with a huge surface area and a totally regular nanostruc- ture; its pores are designed to admit molecules of a particular size. It can also be used as a chem- ical sensor to detect molecules 500 times more sensitively than conventional materials. Such materials are passive nanos- tructures at present, but Brinker plans to develop ones with active pores that open and close as con- ditions change. One possible use might be as a fabric for those working with dangerous chemi- cals which can become imperme- able when hazardous molecules are detected.

Volcanic rock f i l ter media Researchers at Canadian compa- ny, Albarrie have just released the

latest findings from laboratory and field studies on a breakthrough technology utiliz- ing manmade fibres from vol- canic basalt rock in the manufac- ture of filter bags for industrial air pollution control (APC) devices. The original process for extrud- ing basalt rock fibers was devel- oped in the former USSR for defence purposes for applica- tions requiring extreme chemi- cal/heat resistivity. The basalt rock fibre possesses tensile and flex attributes, that Albarrie claim, are superior to those of glass fibres widely used today. By combining the robust physi- cal properties of the basalt rock and advances in composite tex- tile fabric manufacturing tech- nologies, the researchers have developed composite filter bag fabrics that are extremely resis-

rant to the harsh environments of industry baghouse units. Results from laboratory and extensive field testing have revealed that the fibrous rock based fibres provide durability characteristics that rival the more expensive PTFE treated fibre media. F o r m o r e i n f o r m a t i o n c o n - tac t : Greg Rice, tel: +1 336 472 9617; fax: +1 336 472 8437; E-mail: gtrice@ibm.net

MicrofUters help produce energy f rom waste Researchers at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart and the Schwarting-Uhde company in

Flensburg have used filters to improve the technology involved in the generation of energy from rotting waste. They have succeeded in reducing the

dry organic matter which makes up around 60 percent of such residual waste by almost 90 per- cent, simultaneously doubling the yield of bio-gas. Fraunhofer researchers refined the normal two-stage process, adding micro-filters to the sec- ond phase of processing under hermetically sealed conditions. Sludge liquor passes through these filters while the residual mass continues to rot, and shrink to less than half the vol- ume in comparison with earlier

processes. The scientists then apply air to the biomass, and treat what remains with special fungi in order to reduce the amount of lignin in the biomass, which is not easily broken down through fermentation. Finally, the mass is digested one more time, further reducing the residual volume. The odour-free residual solids can then be dis- posed of at landfill sites. The sys- tem, the researchers claim can be easily retrofitted to existing fermentation plant. Results achieved using the system already fulfil the latest technical requirements for disposal of domestic waste in Germany, due for enforcement as of the year 2005. The process is not only suitable for the treatment of household waste; tangible benefits are also gained through the reprocessing of other organ- ic forms of waste such as biowaste, slurry, sewage sludge or natural materials used by industry.

Process and Apparatus for Recovery of Acid Extruded Thermoplastic Foams Useful in Gases f r om Flue Gas, Spray Drying Systems Inc., F i l t ra t i on App l ica t ions , The Dow Chemical USA. WO00/04983. Date of Publication: 3rd February Company., USA. WO00/06284. Date of Publication: 2000. 10th February 2000.

Retention of Filter Elements, ScapaGroupPIc., UK. Bromate/Bromine Filter Cake Removal Fluid, WO00/04975. Date of Publication: 3rd February 2000. Tetra Technologies Inc., USA. WO00/08112. Date of

Publication: 17th February 2000. Moving Sorbent Filter Device, Minnesota Mining and Manufacturing Company, USA. WO00/06288. Cel lu lose Acetate Semipermeable M e m b r a n e Date of Publication: 10th February 2000. and Method for Producing the Same, Daicel

Chemical Industries Ltd, Japan. WO00/09247. Date of Publication: 24th February 2000.

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