• 15 May – Training Course: Industrial Solid-Liquid Separation Equipment, Runcorn, UK
• 2 October – Training Course: Filter Testing and Characterisation, Chester, UK
• 3 October – Filter Testing and Characterisation Conference and Exhibition, Chester UK
• 3 October – Annual General Meeting
• November – Training Course: Membrane Filtration and Separation Technology, UK

15 May – Training Course: Industrial Solid-Liquid Separation Equipment
Runcorn, UK

The course is of interest to engineers, scientists, managers and other technical personnel involved in solid-liquid separation in the process and related industries. They will find the course informative, regardless of whether they design, purchase, research or use filtration and separation equipment. Plant engineers, technicians and operators will find the course materials directly applicable, and graduate students will value the expert introduction to the technologies.

The course is a review of the processes involved in the separation of solids from liquids. It will draw upon the presenters in depth knowledge of industrial applications and extensive R&D experience, and the emphasis will be on practical aspects with theoretical information presented only where needed to support understanding of the applications.

Scope

• An insider’s view of the solid-liquid filtration market
• Ordering and buying solid-liquid separation equipment
• Guidance on selling solid-liquid separation equipment
• Practical aspects of the basics of sedimentation and filtration
• Clarification and cake filtration
• Membrane filters
• Centrifugal separators
• Pressure and vacuum filters
• Selection, analysis and simulation of SLS equipment

Register and pay for this event securely online now.

2 October – Training Course: Filter Testing and Characterisation
Chester, UK

The Filtration Society’s Filter Testing bi-annual international conference and exhibition is one of the most attended events promoted by the Society. The main one-day event will be preceded by a short course and workshop.

The short course will introduce all the fundamental principles of both liquid and air (gas) filter testing in a relaxing and non threatening way where delegates will have plenty of time to ask some of the questions that might be withheld in a more formal lecture environment. The introductory session will give an overview of the need for testing and differentiate between media testing and filter system testing in both wet and dry applications. In addition, the fundamental mechanisms of filtration and the classification of filter media will be covered. Most importantly, the selection criteria for a filtration process will be discussed. This is such an important subject because so much money can be lost by using inappropriate filter systems.

Having established the generic filter most suitable for a given application, the various tests for performance, such as porosity, pore size, dirt holding capacity and integrity testing will be discussed. Integral to nearly all filtration processes is an understanding of particle size so the methods and the information they produce will be reviewed. An additional topic included this year is testing of elements and filters to ISO and other standards, in addition to testing of the filter media.

All the themes highlighted in the introductory session will be developed and exemplified during the day, which will culminate with a discussion of the large array of international standards that apply in the filtration industry. A range of leading testing equipment will be available for close inspection and discussion during the day.
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3 October – Filter Testing and Characterisation Conference and Exhibition
Chester UK

Filter testing is a critical feature of quality control during filter element manufacturing and integrity validation during filter operation. Equally important in filter applications is as complete an understanding as is possible of the feed to be filtered, which requires characterization in many different ways. This one day conference will bring together people interested in characterization and testing technologies that are being applied in industry, as well as those that are about to become industrially accepted methods. From tightening legislation to the growing number of finer, more demanding, filter processes, new filter media developments are constantly being driven by customer requirements. This and newer regulatory frameworks and standards require ever better test methodologies. It has been 2 years since the last filter testing one-day meeting was organised by the Society, and since then new developments have taken place in both gas and liquid applications. This meeting will feature key elements of these developments, and will be of particular interest to process engineers, designers, technical and R&D staff, research institutes and decision makers.

An exhibition of characterization and test equipment will complement the conference, where some of the latest technologies in the market place will be demonstrated by manufacturers and suppliers.
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3 October – Annual General Meeting

November – Training Course: Membrane Filtration and Separation Technology
UK

Details of this course will be posted as soon as they are available.

18 May 2011 – Short Course: Principles of Industrial Filtration
Runcorn, UK

This short course is a review of the processes involved in the separation of solids from liquids, which emphasises practical aspects and presents appropriate theoretical information.

7 June Technical Visit to BOC, Brinsworth (Rotherham)

Overview of Separation Processes used by BOC, followed by plant tour and visit to Remote Operating Centre. BOC has invited The Filtration Society to visit its Brinsworth production facility in order to see filtration on a large scale for air pre-treatment and cryogenic separation.

12 October – Short Course: Media for Gas and Liquid Filtration
Chester, UK

This course is of interest to engineers, scientists, managers and other technical personnel concerned with filter media and their applications in solid-liquid separation and solid-gas filtration processes. They will find the course informative, regardless of whether they design, purchase, research or use filter media or filtration and separation equipment. Plant engineers, technicians and operators will find the course materials directly applicable, and graduate students will value the expert introduction to the technologies.

The course is a review of the processes involved in the manufacture, properties and applications of filter media used in liquid and air (gas) filtration. It will draw upon the presenters in depth knowledge of industrial applications and extensive R&D experience, and the emphasis will be on practical aspects with theoretical information presented only where needed to support understanding of the applications. The topics that will be covered include:

• The Role of Media in Filtration
• Fibres and Yarns for Filter Media
• Woven Media – Production, Structure and Properties
• Non-woven Media – Production, Structure and Properties
• Membranes and Reactive Media
• Testing Filter Media for Gas Applications
• Characterising and Testing Filter Media for Liquid Applications

13 October – Filter Media 5
Chester, UK

The filter medium is the critical component that determines whether a filter process will perform adequately to give the desired separation efficiency. One of the key roles of a filter medium is to create a clear separation of particulate from a fluid or gas with the minimum consumption of energy. This one day conference will bring together people interested in advances in new filter media that are being applied in industry. From tightening legislation to the growing number of finer, more demanding, filter processes, new filter media developments are constantly being driven by customer requirements. It has been 2 years since the last filter media one-day meeting organised by the Society. Since then new developments have taken place in media for both gas and liquid applications. This meeting will feature key elements of these developments, including the role of design of media, recent products grown from industrial R&D, and different modern filter media technologies in successful applications case studies. The continued development of filter media is key in many filtration processes and will be of particular interest to process engineers, designers, technical and R&D staff, research institutes and decision makers.

13 October – Annual General Meeting

Whilst considerable effort has been made to ensure the accuracy of the information provided, the Society accepts no responsibility for any losses which may arise from errors or misuse of the site.

The statements and opinions in the articles and paper abstracts are those expressed by the contributors and as such The Filtration Society assumes no responsibility for them.

Towards Formation of a Society

On 8 July 1964, at the invitation of the Editor of the magazine Filtration (formed in 1964 by combining Filters and Filtration Engineering & Technology), a meeting was held at 5 Belgrave Square in London to discuss the feasibility of forming a Filtration Society in Britain. Just over 40 people attended, representing as many companies in the filtration industry. In the discussions that followed an outline of the Editor’s vision of a Society based on Commission Filtration in France, a specialist group of the Association Nationale de la Recherche Technique, arguments both for and against the formation of such a Society were put forward. The general opinion that emerged was that many aspects of filtration knowledge were being neglected and that a technical society – not a trade association – might well perform a very useful function, particularly if it embraced users of filtration as well as designers and manufacturers of equipment and media.

Bill Norris, the Editor of Filtration, was instrumental in the formation of The Filtration Society.

A vote was taken on the motion that “A Committee be formed to study the practicability of forming a Filtration Society”. The motion was carried by a large majority and the Editor of Filtration called for volunteers to constitute the Committee. The Committee formed was composed of:

• P. Sweet (Fairey Engineering Ltd.)
• R. Palmer (Palmer Aero Products Ltd.)
• D.G. Hill (Air Control Installations Ltd.)
• L.W. English (Auto-Klean Strainers Ltd.)
• R.V. Shears (Locker Industries Ltd.)
• J.A. Hooton (S.H. Johnson & Co. Ltd.)
• P. Bailey (B. Thornton Ltd.)
• W.G. Norris (Editor, Filtration)
• J.W. Price (Organiser, Filtech International)

The Committee met on 10 August and was joined by H.K. Suttle from Loughborough College of Technology. The conclusions of their discussions were that a Society should be formed, that its name should be The Filtration Society, and that it should be “a technical Society which exists to advance knowledge of filtration, separation and clarification engineering and processes”. The Committee further proposed that if the society is formed it should have three major objectives:

1. To hold meetings for the dissemination of knowledge of filtration, separation, clarification and related processes;
2. To recommend methods of testing and evaluating equipment and products;
3. To study the requirement for the foundation of an institute devoted to filtration technology.

The society should be open to individuals who are users, manufacturers or otherwise interested in filtration, separation and clarification.

The main conclusion, together with proposals for the constitution of the officers of the Committee, subscriptions, and so on, were presented to a general meeting of those interested on 6 October 1964. Over 120 people attended and The Filtration Society was duly formed – 60 members were enrolled on the spot!

The First Year

Approximate eighty members attended the inaugural meeting of the Filtration Society held on 9 February at Belgrave Square. Two papers were presented, the first on Particle Size Analysis by B. Scarlett of the Department of Chemical Engineering, Loughborough College of Technology, and the second on High Efficiency Air Filtration by J.E. Firman, a consultant in ventilation and air filtration. The first Chairman of the Society, H.K. Suttle, opened the meeting and introduced the two vice-chairmen – K.J. Ives, a Reader (later Professor) in Civil and Municipal Engineering, University College London, and L.W. English, Technical Director at Auto-Klean Strainers Ltd.

Harold Suttle - the first Chairman of The Filtration Society.

The first Annual General Meeting of the Society was held on 14 October 1965 at the Royal Society of Health in London. This was a major step in the Society’s development as it presented the first opportunity for the membership to debate and approve the proposed Bye-Laws of the Society and to elect Committee Members for 1965-66. Fifteen candidates had been nominated for five vacancies – the elected members were:

• D.A. Bennell
• J.E. Firman
• A.G. Robertson
• P.L. Pocock
• D.B. Purchas
• W.G. Norris
• J.W. Price
• C.W. Hawkes
• D. McLean Wyllie

In his retiring Chairman’s address, Harold Suttle noted that “…. Invention, engineering skills, and, especially, the proliferation of constructional materials, have created machines which perform their specific duties at a satisfactory efficiency. …. A re-appraisal of technological processes must be made if certainty (in design and operation) is to replace empiricism …. Development (of filter equipment) must proceed along with enquiry into the exact nature of natural processes …. (to) yield information which is directly useful to the manufacturer, or designer …. the Filtration Society exists to provide a means for the continuous dissemination of knowledge applicable to a special field ……” and concluded with “The Society is intended to serve in just this manner, by discussion and, it is sincerely hoped, the establishment eventually of programmes on investigation and fundamental research by industry through the medium of our Society. It may be that the establishment of one or more centres, outside London, would encourage the growth of ideas.”. As will be seen, the Society has largely followed these original guiding principles and would develop to become an international organisation.

In 1964, the Society staged a three day meeting at Filtech International at Earls Court in London. The name of the magazine Filtration was changed to Filtration & Separation and arrangements were made with the publisher to enable all members to receive the new journal regularly. The journal was adopted for publication of the Proceedings of The Filtration Society, an arrangement that was to continue until 1999.

Growth and Consolidation

Membership of the Society grew rapidly. The Society expanded in the UK and overseas through the development of Chapters in North America, Europe and Asia.

On 19 December 1966, Frank Tiller convened a group of Texas based filter people on the University of Houston campus, and the Texas Chapter was soon formed. Initial Chapter activities were modest, but drew wide attention and recognition. Soon individuals from elsewhere followed Frank Tiller’s vision as leaders and pioneers to form local Chapters of the Society across America. They included Stan Lindberg in 1967 in Chicago, Larry Avery in New York in 1968, and Wells Shoemaker in Pennsylvania. As local Chapters sprouted, naturally the focus of Chapters that were geographically remote from the UK was less on the Society but more on local Chapter activities, fellowship and education. In the early 1970’s Tiller and Shoemaker organised and ran joint AIChE / Filtration Society Conferences.

Wells Shoemaker saw an opportunity to form other Chapters of the Society and began efforts around the country. In 1972, he formed the Delaware Valley Chapter with Jim Flood as Chairman, followed by the New England Chapter headed by Jud Brown, the Dixie Chapter with Norris Whiteside taking the lead, and in California with Henry Schneider in the Bay area and Gone Franks in Los Angeles, and with Larry Schwartz at the Great Lakes Chapter. The North Central Chapter followed in the late 70’s with Ric Herrera taking the lead in Minneapolis. With this widespread network of Chapters, The Filtration Society was very prominent in the USA at this time.

A critical event occurred in the spring of 1978 that would spawn the American Filtration Society. Wells Shoemaker and Norris Whiteside travelled to Manchester in the UK for a Committee meeting, carrying two proposals from the USA: it was the desire of the leadership of the American Chapters to band together as the American Program Committee (APC) for the express purposes of staging national meetings, and the Americans wished to stage the 3rd World Congress in 1982 under the sponsorship of the new APC group. After considerable discussion, the Committee of the Society accepted both proposals. The Chapters in America then had a solid foundation with which to build both a unified organisation under the APC name, and to run an important World Congress in the USA. The APC was organised formally in 1978 with Wells Shoemaker serving as Chairman. Later that year he was installed as Chairman of The Filtration Society at the 2nd World Congress in London, and he was later presented with a life membership of The Filtration Society in 1985.

Inauguration of the Dixie Chapter - Wells Shoemaker presents The Filtration Society charter to Norris Whiteside, President of the Chapter (second left) as vice-president Bill Warner (left) and assistant secretary/treasurer George Elliott look on.

Amidst an amount of cross-Atlantic controversy about the operation of the Society and the APC in 1987, three American members tendered their resignations from the Committee. Under their guidance the Chapters in the USA formed themselves into what is now known as the American Filtration and Separations Society.

Meanwhile, the Society continued to flourish elsewhere in the world. In the early 1970’s a Canadian Chapter was formed and the Society’s first outpost in Europe was established in Utrecht on 24 April 1972 when the Netherlands Branch under the Chairmanship of Dick Benjamins was created. The minimum membership for the formation of a Chapter was achieved in Belgium, leading to the formation of the Flemish Chapter early in 1980 with the leadership being assumed by Robert Weiler. The inaugural meeting of the Argentine Chapter was put together by Mino Covo and held in Buenos Aires on 20 December 1979, and of the Mexican Chapter in Mexico City on 18 August 1980, and a South African Chapter was formed under the guidance of Wynand van Wyk in 1983. Others were formed in Malaysia, Russia and India. Some of these Chapters were short lived due to lack of local members or absorbed into national bodies, others such as the Netherlands Branch went on to become filtration societies in their own right.

A clutch of past Chairmen: (l.to r.) Peter Swift, Harry Sanstedt, Dick Benjamins, Wells Shoemaker and Tony Ward.

In 1985, the Society’s branch in Japan was inaugurated during a visit by Albert Rushton. The group became known as the Japanese Association and was led by Mompei Shirato of Nagoya University. Today it remains one of the most active Chapters of the Society; Chapters in Scandinavia, now the Nordic Filtration Society, and India also remain active. The Society enjoys harmonious relationships with filtration groups and societies in over 25 countries worldwide.

In the early 1980’s the Bye Laws of the Society underwent major revision, the Committee became known as the Council and was simultaneously restructured, and the Society was incorporated. Shortly The Filtration Society was to become a Registered Charity in the UK. To most members these changes were unnoticeable and normal business was maintained. Day-to-day matters have always been looked after by an Honorary Secretary, of which there have been surprising few over the years – Bill Norris was the first, later followed by Tony Ward, Peter Swift, Mike Taylor and Richard Wakeman. Financial control has been exercised by a Treasurer, also an honorary position; this is again a position that has been occupied by relatively few people – Alan Robertson, Tony Ward, Peter Swift, Doug Moir, and Andy Walker.

Technical Filtration Matters

From the beginning, the Society organised technical meetings in the UK. The enthusiasm of the Society’s members led to cooperation in the development of a three day technical programme – which was to be held at Filtech (International Filtration Exhibition) at Earl’s Court in London under the chairmanship of Harold Suttle – within months of its establishment. Like all enthusiasm, the keenness of members involved in organising meetings has had its highs and lows, but today the Society still runs a well attended technical programme and cooperates with organisations overseas to set up international conferences. For example, throughout the 40 years the Society has worked with the organisers and played a key role in the development of the technical programmes for the series of biannual Filtech Conferences. In earlier days these were staged in London before moving to Karlsruhe, and later Düsseldorf. The Society has actively published the proceedings of its technical meetings – a compilation of several 1000 printed papers on the subject of filtration and closely related topics.

Mike Taylor opening a Filtech conference.

The records of the Society contain copies of all the earlier conferences starting with “Cost and Performance of Filtration and Separation Equipment” held in 1967, and thereafter covering a diverse range of topics from “Filtration in Medical and Health Engineering” to “Choosing the Right Equipment for Dust Control and Air Cleaning”, from “Current Patterns of Filtration and Separation Research” to “Filtration, Productivity and Profits: Liquid-Solids Separation”. These were generally one day technical meetings that attracted delegates from a breadth of industries, due to their interest and curiosity in the wider aspects of filtration as much as because they directly worked with particular types of filters.

The Filtration Society accepted the role of organising two World Congresses, the 2nd and the 8th in 1979 and 2000 respectively. The authors and the topics presented at these demonstrated the truly international character of the Society, the breadth of interest in a wide range of industry sectors, and the enormous spread of topics that are relevant to the overall subject that we call filtration. The world congress series precipitated a new atmosphere between researchers, users and sponsors of R&D, in which there was greater recognition of the need for the output of R&D to maintain flourishing filtration businesses that could meet the technical challenges posed by tightening legislation – particularly related to environmental matters taken in their broadest sense – and the ever growing desire to manufacture more sophisticated products in the process industries.

Albert Rushton speaking at the opening ceremony of the 8th World Filtration Congress.

To coincide with its organisation of the 8th World Filtration Congress in Brighton, The Filtration Society made 2000 a celebratory year: a new logo was introduced, a new corporate image was adopted, and the Journal and the Transactions of The Filtration Society were introduced. These publications were soon incorporated into a new publication, FILTRATION (no connection with the 1963 magazine of the same name), which is distributed to all members as the official journal of the Society. The World Congress was adjudged a great success and left the Society in a very strong position as the leading international organisation concerned with filtration and separation.

Recognising Excellence

An Awards Trust Fund was established soon after the formation of the Society, for the specific purpose of creating awards to recognise excellent work in furthering the knowledge of filtration and separation.

To encourage advancement in the knowledge of filtration and separation science and engineering, in 1966 the Society instituted a biannual award – the Gold Medal. The medal, bearing the Society’s logo that had been newly adopted at that time and suitably inscribed with the recipient’s name, was made possible by the generosity of Messrs. B. Thornton Ltd. who undertook to provide the medal on a continuing basis.

The first Gold Medal was awarded to Jacob Murkes, manager of the separation research department of Alfa-Laval in Stockholm, in London at the 1966 Annual General Meeting.

The Earl of Bessborough congratulating Jacob Murkes after presenting him with The Filtration Society’s Gold Medal.

To encourage and recognise the achievements of younger people, the Council established the Suttle Award, which was intended to be presented every two years to the author of a sufficiently meritorious technical paper. The Society’s dinner in London on 29 September 1971 marked the presentation of the first Suttle Award.

For a period in the 1970’s the Society also offered Travel and Study Awards to enable younger people to undertake studies into matters concerning filtration at a university or in industry.

Professor Dr Ir Pieter Heertjes presenting Richard Wakeman with the first Suttle Award in London.

The Filtration Society is run by a Council, made up of people who voluntarily give their time freely and without recompense to further its aims. Some are identified in this short history – but there are many others who have contributed to the Society and its activities through participation on Council, organising technical meetings, contributing invaluable advice and assistance with specific projects, and so on. Although the Society is a technically based organisation, its members enjoy international friendship with other people who face similar technical challenges in their working lives – many of whom are willing to exchange knowledge about topics of mutual interest. Although for some readers of this short history memories will be stirred, others may just be curious about the Society, how it came about and how it developed.

Vice-Chairman: Trevor Sparks, Filter-Ability Ltd, Ireland

Immediate Past Chairman: Jack Taylor, Chemviron Carbon Cloth Division

Science Correspondent: Graham Rideal, Whitehouse Scientific Ltd

Treasurer: Neil Burns, Croft Engineering Services

Honorary Secretary: Richard Wakeman, Consultant

Members of Council:

• Lloyd Holliday, Outotec
• Mark Crooks, TSI Instruments Ltd
• Richard Lydon, Clear Edge Group Ltd
• Trevor Sparks, Filter-Ability Ltd, Ireland
• Ken Sutherland, Northdoe Ltd
• Kuo-Lun (Allan) Tung, Chung Yuan University, Taiwan
• Andrew Chalmers, Filter Integrity Ltd
• Uwe Schneider, Gebr. Roeders AG, Germany
• Simon Wise, Walker Filtration Ltd
• Antti Häkkinen, Lappeenranta University of Technology, Finland
• David Dubbin, GEA Process Engineering Ltd

The above members of Council, with the exception of the Honorary Secretary, are also Trustees of The Filtration Society.

Trustees of the Awards Fund

• John Gregory
• Steve Tarleton (Treasurer)
• Richard Wakeman

The Filtration Society technical conferences and visits bring together the industry leaders, and offer networking opportunities to learn about the latest information in filtration and separation technology.

The society’s history dates back to July 1964 when a meeting was held at 5 Belgrave Square in London to discuss the feasibility of forming a Filtration Society in Britain. Just over 40 people attended, representing as many companies in the filtration industry. In the discussions that followed a vision of a Society based on Commission Filtration in France, a specialist group of the Association Nationale de la Recherche Technique, arguments both for and against the formation of such a Society were put forward. The general opinion that emerged was that many aspects of filtration knowledge were being neglected and that a technical society – not a trade association – might well perform a very useful function, particularly if it embraced users of filtration as well as designers and manufacturers of equipment and media.

Read more about the society’s history here.

Washing of disperse solid systems is a widely used and complex operation that is embedded in the process chain. The target of the washing operation can be either the purification of the solid particles or to recover the substances dissolved in the liquid as completely as possible. In many cases hazardous substances have to be removed from solid waste materials before depositing them. Washing is often not only a question of environmental protection but also a possibility for the recovery of valuable substances to recycle them in the process and decrease the demand of raw materials. Since the washing step is mostly integrated into other process operations, it is subject to numerous demands exceeding by far the primary demands, like good separation results and a low specific wash liquid demand. Because of the phenomenology and limits of different washing processes it is difficult to choose the appropriate washing process. Additionally, the transport mechanisms of some washing processes are not yet sufficiently understood.

A broad overview of the existing washing processes, the numerous parameters, and the demands they have to meet is given. Included here are well known examples from different separation technologies for permeation and dilution washing in co-current or counter-current mode as well as new highly efficient and recently developed washing processes. Based on a categorization of the washing processes and the classification of these processes according to their macroscopic transport phenomena, one can compare the existing washing processes and show their individual limits. This can be used as a rough guideline for the choice of an appropriate washing process within the complete process chain of solid/liquid separation.

POLYMERIC AND CERAMIC NANOFIBRES
J. Steffens (pages 26-28)

Nanofibre is a broad phrase generally referring to a fibre with a diameter less than 1 μm. While glass fibres have existed in the sub-micron range for some time and polymeric meltblown fibres are just beginning to break the micron barrier, 0.25 μm diameter electrospun nanofibres have been manufactured and used commercially for air filtration applications for more than twenty years. Several value-added nonwoven applications, including filtration, barrier fabrics, wipes, personal care, medical and pharmaceutical applications may benefit from the interesting technical properties of commercially available nanofibres and nanofibre webs.

This paper is a review of the electrospinning process for making nanofibres and nonwoven nanofibre webs from synthetic fibre-forming polymers. The resulting physical characteristics of nanofibre webs will be discussed. In order to provide a useful context for the nonwovens industry, nanofibre webs will be compared to both meltblown and spunbond nonwovens. The description and comparison of the properties should provide product designers in the nonwovens industry with the tools to generate product and applications ideas about new uses for nanofibres.

THREE STEPS TO A NEW FILTRATION QUALITY: MODERNISATION OF FILTER PLANTS BY REVAMPING
T. Langeloh and R. Bott (pages 29-32)

The standard job of a filter is to separate solids from a liquid and to provide: (a) well dewatered dry filter cakes; (b) clear, particle-free filtrate; (c) washed, clean filter cakes; (d) high and constant liquid and solids flow rates; (e) easy to handle bulks; in a reliable operation without failures e.g. by a clogged or damaged filter cloth. However, filter plants are often not operated under optimum conditions and the results often do not meet the requirements. The discrepancy becomes critical if a filter is used up to its capacity limit or beyond its capability, because of increased production rates, higher quality requirements, the introduction of modern process control or a change of product characteristics, for example, the particle size distribution.

In this situation the decision has to be made whether the production target shall be reached with a new filter or even with retrofitting of the existing filter plant. To answer the question it is necessary to assess the potential of improvement and to have concrete ideas as to which specific measures have to be taken for an effective filter upgrading. For this reason BOKELA developed a 3-step optimisation programme for drum, disc, belt, pan, cartridge, leaf filters or filter presses which is clearly structured in 3 phases with exactly defined decision points. According to the programme numerous filter plants have been already optimised in different industries leading to improved product qualities and operational reliability and capacity increases up to 100%.

EVALUATION OF ELECTROSTATIC FILTER MEDIA FOR AEROSOL SAMPLING AND ANALYSIS
M.M. Abdel-Salam (pages 33-40)

Aerosol particles are released into the atmosphere by different processes with significant effects on human health. During the last few decades there has been increasing interest in the measurement of aerosol particles using a wide range of different aerosol samplers and aerosol filtration is a widely used method for measuring airborne particles. Electrostatic filters have the advantage of high aerosol collection efficiency accompanied by low resistance to airflow when compared to the traditional high resistance fibrous and membrane filters commonly used in aerosol sampling.

This paper investigates the suitability of 3M electrostatic filter media for aerosol sampling and analysis in comparison to some conventional aerosol sampling filters, such as glass fibre and membrane filters. The areas investigated include resistance to airflow, aerosol collection efficiency, loading capacity, weight stability and chemical properties. The 3M electrostatic filter media was found to be suitable for aerosol sampling and analysis (gravimetric and elemental chemical analyses) and was as good as the traditional filters widely used in aerosol sampling.

MEASUREMENT OF BIOAEROSOL FILTRATION EFFICIENCY IN AN ASHRAE 52.2 FILTER TEST FACILITY
W. Tang, M.A. Ramakrishnan, S. Goyal and T. Kuehn (pages 40-44)

A real-time monitor of bioaerosols, Fluorescence Laser Aerodynamic Particle Sizer (FLAPS), was evaluated for its ability to detect bioaerosols and measure bioaerosol filtration efficiency. Biological spores (Bacillus subtilis and Cladosporium sphaerospermum) were aerosolized and injected into a wind tunnel based on ASHRAE Standard 52.2. The sensitivity of the FLAPS was adjusted by the photomultiplier tube (PMT) gain to distinguish between bioaerosols and non-biological aerosols such as polystyrene latex and potassium chloride particles. Suspensions of biological spores were carefully prepared to remove interference with culture media. Aerosol concentrations upstream and downstream of a clean synthetic media filter (MERV-14) with electrostatic charge were monitored by FLAPS and by an Andersen impactor. The calculated filtration efficiency from the measurement of FLAPS was 96% for B. subtilis and 100% for C. sphaerospermum. These results agree with those obtained with the Andersen impactor (91% for B. subtilis and 99.5% for C. sphaerospermum).

PULSED ELECTRIC FIELD ASSISTED SOLID/LIQUID EXPRESSION OF AGRO-FOOD MATERIALS: TOWARDS A NOVEL ENVIRONMENTALLY FRIENDLY TECHNOLOGY E. Vorobiev, L. Praporscic and N. Lebovka (pages 45-49)

In this paper we analyse the kinetics and mechanisms of solid/liquid expression combined with a pulsed electric field (PEF). Experiments were performed with raw agro-food materials (slices of fresh carrots and apples, whole grapes), and with agro-food wastes. The layer of particles was formed in the laboratory filter press cell, connected to a PEF generator. The PEF treatment of different intensity (<1000 V/cm) and duration (10-300 ms) was applied before solid/liquid expression (as a pretreatment) or during expression (intermediate treatment).

The PEF application caused electropermeabilisation of cell membranes and enhanced considerably the solid/liquid expression from studied agro-food materials (from 30-50% before treatment to 70-85% after the treatment). The simplified empirical model of solid/liquid expression fitted the experimental data well for both untreated and electrically treated materials. The PEF treatment also influenced the quality of juices expressed from raw materials. The PEF treated juices were more limpid and pure compared to the untreated juices, probably due to selectivity of extraction from electrically permeated cells. Such juices can be purified and clarified more easily than untreated juices. Therefore, it can be speculated that the novel technology comprising the combination of PEF and solid/liquid expression will generate less quantity of industrial wastes compared to existing transformation technologies.

PARTICULATE EMISSIONS FROM FILTER-BASED GAS CLEANING DEVICES AND THEIR CHARACTERIZATION ACCORDING TO PM2.5 CRITERIA
G. Kasper, J. Binnig and J. Meyer (pages 49-54)

We report on a study of particle emissions from pulse-jet cleaned filter media and filter ageing effects of up to 10,000 cycles, which were obtained in laboratory tests on a VDI test rig, using two measurement systems adapted specifically to determine size selective data according to PM2.5. Time resolved measurements were made with an optical particle counter recalibrated (for the test dusts Pural SB and NF) to directly read dust mass vs. aerodynamic diameter according to the PM2.5 transmission curve. In parallel, a cyclone was used as pre-separator in combination with an analytical filter to obtained emitted dust mass averaged over a number of cycles.

Regarding PM2.5 emission levels, one can draw different conclusions from the same data, depending on whether total emissions per cycle or average concentrations per cycle are reported. The results also illustrate how ageing depends on the type of dust and the duration of ageing cycles. Ageing progressed more rapidly with the coarse, free flowing dust. The 5 s ageing cycles prescribed by VDI and ASTM protocols are too short.

THE PRESSURE-DRIVEN MEMBRANE BIOREACTOR vs. THE ION EXCHANGE MEMBRANE BIOREACTOR FOR THE REMOVAL OF TOXIC ANIONS FROM DRINKING WATER SUPPLIES: ADVANTAGES AND LIMITATIONS
S. Velizarov, A. Barreiros, C.T. Matos, M.A. Reis and J.G. Crespo (pages 54-58)

Two membrane bioreactor configurations, the pressure-driven membrane bioreactor and the ion exchange membrane bioreactor (IEMB), were tested for the removal of toxic oxyanions from drinking water. The results based on a case study – nitrate removal at a treated water production rate of 30 L m-2 h-1 – showed that in both bioreactors the desired water quality in terms of nitrate and nitrite can be achieved. The pressure-driven membrane bioreactor allows for possibly higher water production rates and uses relatively cheaper membranes, however, the water quality control in terms of TOC requires on-line monitoring and a strict regulation of the carbon source addition. This configuration also requires an initial start-up period before achieving a steady state operation because the water and microbial culture are in direct contact.

The ion exchange membrane bioreactor offers the advantage of selectively removing the target anion and producing TOC-free water with practically no initial start-up period. Due to the physical separation of the microbial culture from the water stream, the very low diffusion coefficient of ethanol through the Neosepta ACS membrane used, and the membrane-attached biofilm acting as an additional reactive barrier to ethanol penetration, secondary pollution of the treated water was avoided. The development of cheaper anion exchange membrane (possibly in a hollow fibre form) would make the IEMB process economically competitive.

LINKING DEWATERING PARAMETERS FROM TRADITIONAL, FLUID MECHANICAL AND GEOTECHNICAL THEORIES
R. de Kretser and P. Scales (pages 60-66)

Due to the wide range of research fields requiring an understanding of solid/liquid separation, a range of theories and parameter sets have evolved in parallel. Discussion of the approach from one field of research is seldom discussed in the context of the other. This paper attempts a reconciliation of the key approaches in terms of their respective similarities, advantages and inter-conversion of the key parameters on which they are based. The advantages of such a reconciliation both enables a greater understanding of dewatering in general and provides the ability to readily convert data or utilise test methods from one field of research within another.

Keywords: Specific cake resistance; hindered settling factor; flux density; compressive yield stress; solids stress; consolidation coefficient; permeability; compressibility.

NANOFLUIDICS IN FILTRATION AND PARTICLE PROCESSING
H. Nirschl, R. Wengeler and B. Schäfer (pages 67-74)

The subject of this paper is to give an insight into the fluid dynamics when nanoscale or submicron particles are handled in filtration or separation processes. The differences of the forces on particles in macroscale and nanoscale are presented and discussed in detail. The differences can be separated according to particle-particle interaction, the interaction with the surrounding fluid and the influences of external fields. It is evident that the behaviour of nanoparticles suspended in a fluid depends strongly on the surface properties of the suspended material.

As examples, the flow through a nanoscale packed bed and the dispersion process of nanoscale particles is discussed. It is shown that the permeation through a nanoscale structure is influenced by electrostatic and electroviscous effects. Electrostatic effects have an influence on the aggregate structure while the electroviscous effects directly influence the permeation.

Keywords: Nanofluidics; nanoparticles; electrostatic and electroviscous effects; packed bed; suspension.

INVESTIGATION OF FILTRATION CONDITIONS FOR NANOFILTRATION OF REACTIVE DYE PRINTING WASTEWATER
N.P.R. Andersen, M.L. Christensen, K. Keiding and I. Petrinić (pages 75-81)

One of the major problems concerning textile wastewaters is the coloured effluent from rinsing and washing processes. Although the dye concentration is low, compared to many other chemicals found in this type of wastewater, the water quality is insufficient for reuse or discharge. Application of nanofiltration and reverse osmosis to reduce or remove dyestuff from reactive dyeing operations has been widely explored in the literature and is now applied in many plants worldwide. Less attention, however, has been paid to the membrane filtration of reactive dye printing wastewater containing high amounts of thickeners (alginate).

In this study synthetic wastewater, with a composition similar to reactive dye printing wastewater produced during the washing of printed fabric, has been subjected to nanofiltration. The effects of dye, thickener and salt concentration on the separation efficiency and permeate flux has been investigated. All experiments were carried out with an NFT-50 membrane in a plate and frame module applying constant crossflow and filtration pressures ranging from 200 to 1500 kPa.

The results showed that the presence of alginate in the wastewater markedly decreased the permeate flux compared to wastewater without alginate but with the same amount of dye and salts. Calculations indicated that the reduced permeate flux originated exclusively from concentration polarization (CP) and not membrane fouling. The retention of dye was high (>99%) at all pressures, while the retention of salt, expressed as retained conductivity, increased with pressure from 65% at 200 kPa to 85% at 700 kPa (crossflow 240 L/h). However, at higher pressure and crossflow the retention of salt decreased due to more pronounced CP. Thus, for the filtration of reactive dye printing wastewater, a high retention of dye and salt could be obtained at filtration pressures that were significantly lower than those normally used when filtering textile wastewaters.

Keywords: Nanofiltration; alginate; retention efficiencies; process optimisation; water reuse.

IMPROVING CFD SIMULATIONS OF LUBRICANT OIL FIBROUS FILTER MEDIA
M.J. Lehmann and P.K. Hermar (pages 82-86)

Modelling lubricant oil filter media and its particle collection efficiency is still a demanding but elusive goal. Two key areas of difficulty are the availability of appropriate models for particle collections in simulation programs and the characterisation of the fibrous media. The widely used CFD program FLUENT calculates particle tracks based on the motion of the mass point of a particle. Consequently a particle is only counted as deposited when its centre hits a fibre surface. This model is not appropriate for liquid filtration modelling, as the dominant collection mechanism is interception. Therefore, we enhanced FLUENT by our own subroutines to account for the perimeter of a particle and its distance to a fibre surface which resulted in improved prediction of efficiency for particle removal from liquids.

The challenge to model the fibrous structure of the media remains. Many recent studies attempt to model the 3D fibre structure in 2D by random placement of cylinder cross sections vs. the prior over-simplified approach using perfectly spaced fibres. However, this approach still does not generate a realistic structure and still over predicts pressure drop. So the current work investigates the influence of semi-randomly arranged fibre structures. The resulting fibre structures are more realistic than those created by fully-random placement. Simulations comparing the pressure drop and collection efficiency of these types of structures are shown.

The results demonstrate the effect of the different kinds of simulated 2D fibre structures on pressure drop and collection efficiency. A shift from fully random to semi-random structures results in changes to flow patterns and generally leads to a significant decrease of pressure drop. Furthermore, changing from a staggered fibre grid to more locally aggregated fibre structures increases the media usage through its depth. However, moving from fully random to semi-random structures causes decreases in collection efficiency. The results and discussion briefly illustrate these effects and the challenges for future media modelling.

Keywords: CFD-simulation; fibrous filter; filter media; filter design; modelling.

In many applications, besides the laboratory, there exists a need for the exact characterisation of filters and separators, e.g. in the fields of lubrication oil separation, blow-by oil separation, automotive and engine air filters and compressed air filters. As the aerosol concentration in the different processes may change rapidly, a quick particle characterisation upstream and downstream of the filter is required.

Other problems arising are the different measurement conditions of the application with regard to, for example, the temperature, type of aerosol and pressure conditions during the process. In the past, a user tried to cover at least the problem of varying aerosol concentrations by using two particle counters upstream and downstream of the filter to perform simultaneous measurements. The difficulty in doing so is the exact comparison (calibration) of the two counters with regard to their classification accuracy, resolution and counting efficiency.

Palas® has developed the new aerosol spectrometer welas® 3000 with two integrated sensors for upstream and downstream which allow quasi-simultaneous particle size and particle concentration measurements to be carried out. The sensors may be equipped with different sizes of measuring volume in order to obtain optimised results with regard to different concentrations in a short time. Since the electrical parts, such as the lamp source and optical receiving unit of the scattered light, are the same, the device parameters of the two sensors, such as classification accuracy, resolution and counting efficiency, are the same as well.

The sensors are connected to the control unit via optical fibres. Thus, it is possible to switch quickly between upstream and downstream without losses in the sample lines by simply using an optical switch of the light connection to the sensors. The welas® system may be equipped with internal heating up to 120°C and an aerosol cuvette that is pressure resistant to 10 bar. Hence, the system can be used for the previously mentioned applications. This paper will focus on measurement results, e.g. in the field of lubrication oil separation and on measurements at pressures up to 10 bar with varying upstream concentrations.

CFD ANALYSIS ON THE EFFECT OF CALENDERING OF FILTER CLOTH ON TRANSIENT CHARACTERISTICS OF CAKE FILTRATION
K-L Tung (pages 109-112)

The effects of a filter fabric calendering treatment and the permeability of filaments with regard to the particle deposition phenomena onto or into filter fabrics at the initial stage of filtration are conducted quantitatively using a microscopic forces analysis. The flow pattern and the resistance to fluid flow in the calendered interstices were obtained numerically using the fluid flow software FLUENT™. Based upon numerical data for the continuous phase, a program was devised to simulate the transient behaviours of pore clogging and cake formation by way of the Lagrangian approach. This estimates the change of filtrate clarity during the initial stage of filtration for various calendered fabric porosities and various filament permeabilities.

Results show that in the case of tightly woven filter cloths the flow is predominantly through the yarns of the cloth, while flow will generally be directed around the yarns of a loosely woven cloth, especially if the yarn is twisted tightly. Therefore, filtrations with tightly woven but loosely twisted yarn can increase the unfavourable, but inevitable, clogging problem. The simulated results further show that although the filtration resistance of woven filter fabric increases after calendering, the permeability is rectified and the clogging of the filter pores is also improved. After the calendering of the filter fabric has taken place, only the cake formation mode (in accordance with the law of blocking for all types of pore) is evident. The critical concentration proposed by previous investigators is not observed for calendered filter fabrics.

NEW ISO STANDARDS FOR COMPRESSED AIR ANALYSIS AND FILTER TESTING
S. Smith (pages 112-116)

A large number of the International Standards used within the compressed air industry are either in the process of regeneration or are due for review. In addition, the first complement of compressed air filter testing standards, ISO 12500 Parts 1 & 2, are nearing finalisation with Part 3, Particulates, in development. Further, there are proposals to develop three additional standards for inclusion in the ISO 12500 series. This paper provides an up to date review of the position regarding these standards and details the proposed methodology for ISO 12500-3 coarse particulates testing.

RECYCLING OF PROCESS WATER USING MICROFILTRATION AND NOVEL COMPOSITE FILTER MEDIA S.
Volooj, C. Carr and R. Lydon (pages 117-123)

In this study dyebath recycling and decolourisation using a dual-flocculant system combined with microfiltration has been examined, and typically above 90% of dye removal was achieved. The effects of fluorine treatment on the surface and filtration performance properties of the composite filter media have been investigated, and filtrates with less turbidity and cakes with lower moisture contents were observed. XPS and contact angle measurement techniques were used to characterise the nature of the modification imparted by the fluorine treatment.

APPLICABILITY OF FABRIC FILTERS IN AIR POLLUTION CONTROL (APC) FOR WASTE INCINERATION PLANTS – LONG-TERM EXPERIENCE…
G.G. Pranghofer (pages 124-126)

Continuous development and improvement of high durability laminates led to a large number of reference applications in Waste Incinerators, the long-term performance of PTFE membrane filters in various configurations and different stages of APC systems is detailed. Experience has been obtained over 20 years in all stages of flue gas cleaning, e.g. collectors downstream from the boiler, downstream spray dryers and in end-of-pipe filter systems, covering a temperature range in the collector of 100 – 250°C. The results of the performance in different incineration plants is provided in this paper, including retention rates of PM 2.5, dioxins, heavy metals and, in combination with absorbents, of acidic components (SO2, HCl, HF) in compliance with BAT and the European Regulation (Directive 2000/76/EC of the European Parliament and of the Council of 4 December 2000 on the incineration of waste).

COMPARISON OF DIFFERENT FILTER AID PERMEABILITY TEST METHODS
W. Li, C. Kiser, Q. Richard and E. Mayer (pages 127-132)

Permeability is an important specification for evaluation and selection of filter aid products. However, there has not been a standard filter aid permeability test method in the US. Permeability results published by different companies may not be comparable due to different apparatus, filter paper, cake formation, sample amount, sample preparation, and different driving force used. The objectives of the study in this paper were to (i) investigate factors affecting permeability results in different filter aid testing methods, and (ii) develop a method and procedure providing consistent testing results on different testing apparatus. Three permeability test methods, three grades of rice hull ash and two grades of diatomaceous filter aids were involved in the study. It was found that filter paper or clogging of filter paper, testing pressure, sample preparation are critical factors affecting permeability results. A tight, low resistant and not easy to clog filter paper should be chosen for a permeability test. The testing pressure should be chosen carefully considering the compactibility of samples to be tested. Recommendations on other testing conditions are also given in the paper.

PHYSICAL MEASUREMENT OF PORES BY GLASS BEAD CHALLENGE TESTING
G. Rideal (pages 132-137)

Pore size measurement by the indirect method of porometry can produce varying results, especially for larger pores in excess of about 100 μm. Consequently, ‘bubble point’ rated filters often fail to stop the expected particles in real situations. Historical labelling of filters, and even nominal ISO standard specifications can therefore be very misleading. In this work, narrow particle size distribution glass microspheres from a few microns to several hundred microns were used as challenge particles to assess a number of filter media. A new Sonic filter tester could perform the test in 1 minute in the dry state. The challenge test results were unaffected by the porosity of the samples, unlike the porometry results where large variations were seen. In other examples, a sintered polymer air filter rated at 5 μm had a filter cut point of 140 μm while a nonwoven sand screen used in petroleum extraction rated at 125 μm had a cut point of 395 μm. Recovering and analysing trapped microspheres within the pore structure can be used to measure pore size distribution and also reveal subtle internal details in woven filter media.

TESTING FILTER MEDIA FOR LIQUID FILTRATION
R.J. Wakeman (pages 138-147)

Filter media exist in many forms and with a wide range of properties that are relevant to the filtration process. Not all media have to meet the same requirements when in service and different industries place differing demands on the media. This leads to the need and development of standards that are industry specific in some cases, or media design specific in others. The range of media available is overviewed together with some of the test methods that relate to the ability of a medium to capture contaminants from a liquid stream (other methods that relate to, for example, mechanical properties of the medium are outside the scope of this paper). Integrated within the overview are the standards that have been written by associations with responsibility for representing best practice in particular industries or by national/international standards organisations. Some directions of current research that may underpin future standards are indicated.

NON-WOVEN FABRICS AS SOLID/LIQUID SEPARATION MEDIA IN A MEMBRANE BIOREACTOR
W-K. Chang, S-H. Chuang, A.Y-J. Hu and M-C. Chang (pages 149-153)

The characteristics of non-woven fabrics as solid/liquid separation media in a MBR application have been studied in this paper. To understand the effect of particle properties on filtration performance, inorganic and microbial particle filtrations were studied simultaneously. The results showed that there was no significant decline of permeate flux during 120 h operation for inorganic particle filtration. Comparatively, non-woven fabrics were fouled rapidly for microbial particle filtration and significant decline in permeate flux was observed during experimental periods. However, low effluent suspended solids was achieved rapidly due to the denser cake layer on the fabric surface. This study has demonstrated that non-woven fabric materials could be used as solid/liquid separation media in membrane bioreactors for wastewater treatment. An appropriate operating strategy, like optimum operating flux and fouling control, is needed for long-term stable operation.

Keywords: Membrane bioreactor; filtration; fouling; non-wovens; solid/liquid separation; wastewater.

MEASURING PARTICLE DEPOSITION WITHIN FIBROUS FILTER MEDIA BY MAGNETIC RESONANCE IMAGING
J. Hoferer, E.H. Hardy, J. Meyer and G. Kasper (pages 154-158)

This paper describes the application of magnetic resonance imaging (MRI) to obtain information on local particle mass deposition within fibrous filter media. The experimental set-up used for on-line loading experiments is also detailed. The required procedure to initially gather information on filter structure without destroying it, which is required when the same filter medium is later loaded with particles, is briefly presented as is the particle size distribution of the particle material used to load the filter in comparison to a conventional test dust. Preliminary results are discussed for recording the loading process within a medium by visualizing the local deposited mass at various loading stages. By using this non-destructive measuring technique which first allows measurement of the internal fibre structure followed by loading of the medium, it will be possible to compare the data with results of simulations and thereby allow validation of kinetic filter models.

Keywords: Depth filtration; fibrous filter; gas filtration; MRI; particle deposition.

FILTERABILITY AND AGEING OF CRYSTALLINE POTASSIUM SULPHATE SALTED-OUT WITH ETHANOL AND ACETONE
M. Louhi-Kultanen, A. Llansana Arnalot, L. Nyström and J. Kallas (pages 159-167)

The desupersaturation and ageing of a solid/liquid suspension consisting of crystalline and dissolved potassium sulphate, co-solvent water and an anti-solvent, i.e. acetone or ethanol, were investigated based on image analysis, measurements of electronic conductivity and determination of certain filterability parameters. The crystals were produced by salting-out precipitation at 25°C. The samples were taken after addition of the anti-solvent in a semi-batch process by pumping the precipitant at constant flow rate or in a batch process by adding all the anti-solvent at the beginning of the precipitation process. The studied ageing time was 60 mins. Ostwald ripening theory was utilized to compare the ripening tendency in the studied solvent systems. The precipitation conditions were changed by altering the flow rate of the precipitant. The solution composition was changed by adding sulphuric acid to decrease the pH from a neutral solution pH equal to 6.2. Ageing for 60 mins. decreased the cake resistances of both studied precipitant systems whereas cake porosities varied only slightly between fresh and aged precipitate cakes.

Keywords: Filterability; ageing; stability; out-salting precipitation; potassium sulphate; desupersaturation.

TUBE SETTLERS FOR THE ENHANCEMENT OF SETTLING TANK CAPACITY
K. Fujisaki and M. Terashi (pages 168-172)

A new type settler has been developed and its usefulness was confirmed experimentally. The device arranges inclined parallel plates in the vertical direction, contrary to the usual horizontal arrangement. In this method, the separated clear water is removed directly by suction from the top end of the parallel plates. For the removal of clear water, the right and left edges of the plates are closed in order to make a tube with a rectangular cross section. These are the unique and original features of the equipment. The treatment capacity is proportional to the number of settling tubes set in the suspension, since each settling tube acts as a small settling tank. The new settling tube module was set in a final settling tank and over a wide range of sediment concentration the relationship between the suction velocity and suspended sediment concentration of effluent was investigated. Based on the results of these on-site experiments, it is demonstrated that the new tube settler system is very effective for the enhancement of settling tank capacity. A numerical estimation of the application of this system to a practical settling tank also confirms the effectiveness of the device.

Keywords: Lamella settler; settling tank; tube settler; sedimentation; thickening; clarification; sewage secondary effluent; activated sludge.