Efficient, cheap, and compact filtering

Challenges with the filtering at a juice factory, rollers from a couple of old typewriters and a lot of time. This could be the formula for the creation of Dacofi, a new company, which produces solutions for advanced separation and filtering.

It smells of hobs – and this for a reason. At the pilot plant of DTU Food in Lyngby, they are brewing lots of beer, and today four trainees are visiting to learn about the mysteries of brewing, competently supervised by Preben Bøje Hansen.

Preben Bøje Hansen is a food technician, and together with his colleague, Peter Stubbe, he has invented a filtering machine, compact filtering, which, among other things, can be used for beer brewing.

During the interview he runs back and forth to help the students secure optimal temperatures in the big beer tank. He also has time for checking emails on the telephone, discussing school politics, sketching, and making small models with random items within reach to illustrate the principles of the technique, which forms the basis of the new company called Dacofi. All served with ice-cold draught.

“Today I would like to focus on the three elements, which are definitely going to be part of our business model. But there are more to come,” Preben Bøje Hansen promises and quickly mentions another 2 or 3.

You see, after many years’ work with developing the new technology, things have started to speed up. Dacofi offers solutions for filtering big quantities of material in connection with for example the production of potato flour, beer brewing or the treatment of wastewater.

You take four beer glasses …
Most of us regularly filter material, for instance when brewing coffee. The process leaves us with waste, in this case coffee ground, which in professional circles is called the filter cake. Sometimes you throw out the filter cake together with the filter, other times the filter must be emptied and cleaned, before you can continue.

When it comes to facilities for the industry, handling the filter cake is difficult, because the process has to be stopped while cleaning and reassembling the machine.

”My colleague Peter Stubbe and I had the idea, when we were working on a project at Vallø Juice. They filtered the fruit in an old fashioned so called Bückerpress, and we agreed that we would be able to do that much more efficiently. So we went home and found out how,” Preben Bøje Hansen tells.

Preben Bøje Hansen and Peter Stubbe became colleagues at DTU in 1994, and soon after they created an inventors club for discussing ideas such as the alternative juice press.
The principle behind the new filtering machine is simple, but you have to let go of the image of filter coffee, because the process is not necessarily horizontal like in a coffee brewer. To illustrate this, Preben Bøje Hansen puts four big beer glasses close together, resulting in a cavity in the middle. Two of the glasses are up side down.

“The four glasses represent rollers, each rotating around its own axis. Two of them are covered with rubber, and the remaining two are full of holes and function as filters. The rubber rollers press the material into the filters, and the filter cake is continuously removed by a scraper situated on the side,” he explains.

This way the filter cake is left sitting on the outside of the two filter rollers – ready to be scraped off, and this process can run for hours, all day or for weeks without cleaning. However, when it comes to the production of food, all parts must be cleaned daily for hygienic reasons.

The advantages of Dacofi’s filtration principle are:

  • The process runs continuously, which means no stopping the production
  • The filter is cleaned regularly, and this ensures a high filtration performance
  • The process is energy efficient, because the friction of the moving parts is low, and the constantly clean filter provides a low pressure drop
  • It is inexpensive both to construct and to maintain 
  • The process is quiet, because none of the machine parts move quickly
  • The filter cake is very dry, which means that less liquid is wasted, and it is easier to dry completely afterwards
  • The machine easily handles everything from water to fluids with high viscosity
  • The machine easily handles materials with a high content of dry matter
  • The machine is compact and takes up a minimal amount of space on the floor

Blue Book, Preben Bøje Hansen, 59 years

2011: Established the DTU Brewery, where he is currently the head brewer
2008: Employed by The DTU Food Institute
2006: Course in Aseptic technology, Perdue University, Indiana U.S
2004: Educated as Safety Supervisor
2003: Safety Supervisor at Biocentrum (previously Biotechnology)
1995: Employed at the Institute for Biotechnology
1993-95: Trained as food technician

Preben Bøje Hansen is the father of five children and lives with his wife, Helle, in Herlev. He feels most relaxed when his mind is working on a problem. He usually gets the best ideas in his summerhouse, which is situated on a hillside 100 km from Rome, which he has restored himself.

Preben Bøje Hansen defines the progress of Dacofi as very stimulating, and hopes that in ten years from now he will be head of the development department.

Financial support

  • The DTU Food Institute granted DKK 50.000 to the development of prototype number two
  • GAP funding and a grant from Otto Bruun’s Foundation funded one prototype
  • Jan Hansen funded two prototypes
  • Copenhagen Spin-out’s has granted 120.000 DKK for a prototype, 50.000 DKK for consultancy support for the development of a business plan and 20.000 DKK for a market analysis
  • Proof of Concept-means were applied for but not awarded

Thanks to a grant from CPH Spin-out, Dacofi has managed to engage Julia Budolfsen, a business development consultant, to set up a professional business plan. It will contain three different focus areas.

1. Dacofi’s filter rescues animal feed
1/3 of all the food on the planet (also for animals) is wasted. There is a need for implementing methods in the food industry, which prolong the shelf life, and here Dacofi’s filtering method can prove useful.

“We already have a license agreement with a big Swedish company, Larsson AB. They constructed a facility capable of filtering 30 m3 per hour using our method,” Preben Bøje Hansen explains.

Larsson is interested in the technique because they develop process lines for the production of tapioca and potato flour. You can dry the residual product (potato pulp) and use it as animal feed, but in some areas the climate change has brought more rain and thereby impeded the traditional outdoor drying.

"Compared to other filtration methods, the filter cake from Dacofi’s machine is extremely dry, making it easier to use the residual product in areas with a humid climate," Preben Bøje Hansen says.

2. The brewery can make use of everything
A major brewery is currently negotiating with Dacofi, because the filtration has proven so efficient that it draws a heap of useful substances from the dry matter of the filter cake into the liquid.

"We want to do more research on how to utilize fibers, proteins and minerals from the liquid. The fibers are very healthy and can for example be used for infant formula, and the proteins are great for men dreaming of big muscles. The dry matter can be burned or used in the production of natural gas. Or you can dry it completely and turn it into animal feed or flour," Preben Bøje Hansen says.

The food industry can use the flour as filler where they currently make use of potato flour. The advantage of the new type of flour is that it effectively binds the water, which results in a lean end product.

However, also in this case it is a very significant advantage that the filter cake is easily dried completely, and can be used as animal feed.

3. Household waste is fully utilized
The last focus area in the business plan is about utilizing the organic material in waste from ordinary households. The waste is sorted mechanically, suspended with water, and enzymes are added to the mixture.

Next, the solution is filtered, and this can of course be done with Dacofi’s technology. The water is recycled, and the dry matter is transferred to fermentation vessels, where it is converted to biogas.

Filters based on the Volkswagen principle
The implementation of a large-scale production, based on Dacofi’s filter method at Larsson AB is the result of many years of development at the Food Institute’s pilot plant.

"It has been more than 13 years since we got the first idea for the project in Vallø. We then spent a few years making the patent, and built the first prototype out of old parts from typewriters," Preben Bøje Hansen says. He has saved both this and the next four prototypes, which were necessary to build before the efficiency was satisfactory.

It was mainly the operation and durability of a thin filter, which was challenging, but virtually all parts of the machine have been given serious thought with regard to the choice of materials, durability and price.

"Of course, it has been necessary for us to invent many of the parts ourselves, and it takes a long time when it must be done in our spare time. The goal has always been to create a filter solution like a Volkswagen; it must be efficient, inexpensive and robust, " Preben Bøje Hansen says.

Therefore they have chosen to initially produce filters at the size of 50-300 μm. These have been thoroughly tested and perform undoubtedly. The first version of the product is ready, and it is time to leave the safe environment of the DTU. At first, The Green Entrepreneur House at Risø will be Dacofi’s the new home.

The company has been long in the making, but is has come far when it comes to product development, and here Preben Bøje Hansen has no doubts as to the decisive matter. And to what still means everything, when it comes to future efforts:

“Without my network we would never have come this far. I know a lot of people from the industry – both directors and especially standard employees, who, along the way, have participated and given their opinions. This doesn’t happen by itself, it’s something we have built parallel with the development work.”

The young beer brewers are getting ready for the next step in the brewing process, and Preben Bøje Hansen is in position. He has many years of experience – last summer at the People’s Meeting, the DTU served 1000 liters of draught beer to the guests, produced at the pilot plant of The Food Institute. If Dacofi becomes a success, The Food Institute will have to find another head brewer, because the new company’s development department will need an experienced leader.

Learn more about the technique on www.dacofi.dk

Dacofi is divided into two units:
Dacofi Holding handles the rights, and Dacofi Separation deals with sales, production and marketing.

Four patents have been taken out between 2001 and 2012.

The founders of the company are Preben Bøje Hansen, Peter Stubbe, and Jan Hansen. Currently Jan Hansen is the CEO, but he’s going to resign to dedicate himself to his own company, Al-2 teknik. A new CEO is on the way.


24.06.2015 DTU search engine outmatches Google 23.06.2015 IT’S PURE PLASTIC 17.03.2015 Efficient, cheap, and compact filtering 24.09.2014 Intelligent syringe creates new company 17.09.2014 A gel without taste
Se alle Spin-outs historierne