Kemic Airlift: removing aggressive carbondioxide (CO2) without chemicals

Kemic Water Treatment has developed Airlift; an innovative solution for removing aggressive carbondioxide (CO2) from drinking water, completely without use of chemicals. 

Aggressive carbondioxide (CO2) is primarily found in areas with soil low in lime. Carbondioxide is lime dissolving, which can cause damage to pipes both at the water treatment plant and in the supply network. For many years, it has therefore been common to add lime to the water in order to remove the carbondioxide and increase the pH-level to the desired level according to regulations about drinking water quality.

Aeration as the only means

Using Kemic Airlift, a new method developed by Kemic Water Treatment in collaboration with independent advisor Henrik Aktor and Aquatarium in Ringkøbing, Denmark, the CO2 is now removed from the water using only oxygenation. Oxygenation has previously been used as part of the water treatment to increase the effect of the chemical materials being added, for instance lime or lye, but never in full scale as the only solution to aggressive carbondioxide. It requires special placement and fitting of the system to create the proper flow to the clean water tank at the waterworks, as well as dimensioning and configuration of the oxygenation, which Kemic Water Treatment has now developed.

Up under the ceiling

Since Airlift requires free flow from the clean water tank at the waterworks, it is necessary to carry out assembly and fitting at great heights, when Airlift is installed, says technician at Kemic Water Treatment, Finn Pedersen:

– Someone who is afraid of heights can’t work with installing Airlift, since we are working at 10-11 metres height. But it is impressive to see the guys almost fly around up under the ceiling, of course while adhering to all safety regulations, Finn tells.

In operation in Ringkøbing, Denmark

The new system for removing aggressive carbondioxide is installed at Aquatarium near Ringkøbing, where increased levels of aggressive carbondioxide (CO2) were detected in the pumped raw water for a period of time. Aquatarium asked Kemic to present some suggestions for solving the issue, and the innovative solution where no chemicals are used were chosen, since Aquatarium in general prefers the best possible solutions without using chemicals.

The system is developed in collaboration with Henrik Aktor from AKTOR Innovation ApS, civil engineer and PhD, who has carried out modelling and calculations in order to reach the best possible solution. Henrik Aktor tells about the collaboration:

– Our water supply in Denmark is constantly challenged with new contaminations and increasing issues, so it’s great that we can join forces in the business when finding the solutions. I contribute with mostly theoretical knowledge, calculations and modelling, which we then use to draw up a solution together, and Kemic implements. The collaboration has been characterised by great trust and a shared ambition to find the best possible solution.

Also the collaboration between Kemic and the client, Aquatarium, has been great. It was an advantage that Kemic has actually delivered the big water treatment plant near Ringkøbing back in 2016.

– Our collaboration with Aquatarium is outstanding. They want the best possible solutions, and the people at the water treatment plant are just as nerdy as we are, so we speak the same language and get things done. It’s a please, tells Finn Pedersen, technician at Kemic Water Treatment.

The good and already long-term relationship with Aquatarium has especially been an advantage since Airlift is a new product, Finn explains:

– Aquatarium is the first site where we installed Airlift, and it was a big advantage that we already know the waterworks really well. But now that we’ve done it once, we can install Airlift anywhere.

Low maintenance and operation costs

Kemic Airlift requires a minimum of maintenance, since there is no filter material to add regularly, which is the case with using addition of lime as a solution to aggressive carbondioxide (CO2). The system comes with a control system so that it can be controlled and monitored as part of the daily operation of the waterworks. Since the oxygenation happens to the processed water right before it hits the clean water tank, there are no filters being clogged up with unwanted contents. In addition, it is a more hygienic solution. Thus the system is very low maintenance and there are no costs for more filter material.

Retrofitting without stoppage of operation

At waterworks with more than one operating line, Kemic Airlift can be retrofitted without any stop in operation or reduction of capacity in the installation period. Operation is stopped on one line at the time for short periods of time only while assembly and fitting is carried out. It is also possible to bypass Kemic Airlift after fitting.

Soil and groundwater conditions determine if removing aggressive CO2 is necessary

Aggressive CO2 is found in groundwater primarily in areas where the soil is low in lime, which in Denmark is mainly in Jylland and some places on the island of Funen. That is due to the geological development during the ice age, where the ridge of Jutland marks a great difference in the groundwater. The further West you travel, the larger concentration of aggressive CO2 is usually found.