July 2014

Sustainable water environment for the coming generations

Being located in the northern part of Jutland should normally indicate that everything is a little slow and behind Copenhagen. However, the northern part of Jutland is in the front when it comes to innovative thinking and ensuring coming generations will be motivated to look into the scientific education sphere when they join Universities.

Aalborg University, Aalborg Municipality, Tech College Aalborg and University College Nordjylland have joined forces and created “Universitarium” which is a yearly event for young people still in primary school and gymnasium where they can experience innovative products and projects within the scientific world. The aim is to encourage the young people pursuing their scientific interest also when joining the Universities. In the summer period, it is an open event for everybody interested in science. Besides all the different products displayed also a number of scientists are in charge of many practical events giving the young people the lesson that besides being interesting the scientific world also is a practical world where your skills create a better world.


This year the theme is “Water”. Water is the foundation for life. Water is covering some 70% of our Earth. Water is the road for transporting the major part of all products carried around the world. Even though Denmark is a small country, we are still one of the bigger players within the Maritime World. When it comes to innovation within the Maritime World, Denmark is in the front. Being in the front from a technical point of view also create the responsibility of creating sustainable solutions ensuring the coming generations also have a wonderful world to live in.


This is where DESMI Ocean Guard comes up; ensuring that “the so-called Invasive Species” are not transported to places where they can create a lot of problems for the local environment. According the IMO (UN body for the maritime world) invasive species are among the four biggest threats worldwide.


DESMI Ocean Guard has developed a very environmentally friendly Ballast Water Treatment System called RayClean. It is a combination of fine filtration – 30 micron, and Low Pressure UV radiation. We are exposing the organisms being able to pass the filter to an extreme sun radiation, causing destruction of the DNA string and consequently not allowing the organism to reproduce itself. The organisms may not necessarily die immediately. However, tests are showing they are not able to reproduce themselves, meaning we will avoid spreading of the organisms.


The advantage of using low pressure UV is that some 30 – 35 % of the lamp energy is converted into UV light. Meaning that we can treat 100 m³ of water with less than 6 kWh energy. One critical factor for UV light is the ability of the light to penetrate the water. The more colored water the more critical it is for the light to penetrate it. The expression UV Transmission (UV-T) is used for telling how much of the light is passing the water. E.g., UV-T 0.8 means that 80 % of the light is passing the first cm of water, 80 % of the 80 % is passing the next cm, and so forth.

DESMI Ocean Guard RayClean system is tested down to UV-T 0.33, meaning that only 33% of the light will pass the first cm. This is top of the class. Most systems will not test the system when the UV-T level is below 0.5. In the real world there are harbors going down to 0.33 in UV-T.


Further DESMI Ocean Guard developed the first system also being able to operate in fresh water. The main difference for the organisms living in fresh water compared to salt water is that fresh water organisms are softer than salt water organisms. Meaning that even though the organisms may be some 80 – 120 micron in size in fresh water they may be able to pass the 30 micron filter. The larger the organism is the more UV energy is necessary to “kill” the organism. Meaning that the risk for the organism to survive the treatment is higher the larger the organism is. But again, DESMI Ocean Guard was the first manufacturer being able to pass the fresh water test.


The DESMI Ocean Guard system is designed with UV cassettes each having treatment capacity for 300 m³/h flow rate. When the flow rate from the ballast pumps are higher more cassettes are placed in parallel. For cleaning the system the cassette has a built-in scraper moving through the entire cassette and having holes for each of the 60 UV lamps placed inside the cassette. Meaning that no chemicals are needed at all in this system. Neither during treatment nor cleaning.

The system is used both during water intake and during water discharge. The holding period in the cassette is approx. 5 seconds, and it is during these 5 seconds the actual UV radiation/treatment takes place.


Are the young people interested in DESMI Ocean Guard’s RayClean system and the environment? It seems so :-)

DESMI Ocean Guard A/S is now belonging to the DESMI Group, and a separate entity within the group. The company was founded 5 years ago as a joint venture between DESMI, A.P. Moller – Maersk and UltraAqua. It is a small, dedicated group of engineers with different expertise having designed, developed, tested and being in charge of selling and producing the systems. It is a company where each member of the group is important, and it is a company where you have to navigate outside your expertise. Allowing you constantly expanding your knowledge.