Research & Innovation

Substitution of Biocides in Cooling Water Treatment

Blue Activity Develops Process for Water Treatment of Industrial Evaporative Cooling Systems with Microorganisms

13.12.2023 - The Heidelberg-based start-up Blue Activity replaces 100% of biocides in cooling water treatment with natural, functional microorganisms. The product change increases the efficiency of cooling tower performance and reduces water consumption and operating costs.

The Heidelberg-based start-up Blue Activity replaces 100% of biocides in cooling water treatment with natural, functional microorganisms. The product change increases the efficiency of cooling tower performance and reduces water consumption and operating costs. The microorganisms introduced ensure continuous deep cleaning throughout the entire system. Future requirements from the national water strategy can thus be implemented easily and cost-effectively. In an interview with CHEManager, founder Lars Havighorst explains the disruptive solution.

CHEManager: What motivated you to found Blue Activity?

Lars Havighorst: We started in 2021 as a CleanWaterTech start-up. Our vision is to protect drinking water as a resource by improving water quality and significantly reducing the quantities used. We see water treatment in industrial evaporative cooling systems as a big lever for this. We not only wanted to optimize the treatment agents used, but also revolutionize them with a fundamentally new form of treatment. With our disruptive approach, we are completely replacing biocides with natural functional microorganisms. We want to make a difference in a market where there has been little innovation in recent years.

What distinguishes your solution from others available on the market?

L. Havighorst: The functional microorganisms we use do not have a biocidal mode of action, as is usual in industrial water treatment for the legally required hygiene safety. Our process does not promote the development of resistance. We ensure permanently good water quality and protect biodiversity in surface waters. In addition, our solution is economically attractive and thus forms a perfect symbiosis for the customer.

How does the industry benefit from the solution?

L. Havighorst: Industries whose energy-intensive production processes rely on an efficient cooling process benefit economically and ecologically. In addition to lower energy and water consumption, the use of hazardous substances can be completely eliminated. In many systems, hidden biofilm ingress leads to disruption of heat transfer and inefficient cooling performance and increases energy and water consumption. Traditional biocide applications can only reduce this effect to a limited extent, as they mainly act in the flowing medium. They often have little or no effect on surfaces and pipe walls. In contrast, our functional microorganisms are active throughout the cooling water system and ensure a natural deep-cleaning effect in the water-bearing systems. As a result, cooling performance is improved and maintenance and servicing costs are reduced. Neither the materials nor the wastewater will be polluted in the future.

The industry is currently investing in energy and CO2 reduction. Where does the topic of water stand?

L. Havighorst: There is no doubt that water is not yet at the top of the industry's agenda. However, it is becoming increasingly important, as politicians want to protect the right to high-quality and affordable drinking water for all with the National Water Strategy adopted in March 2023. Today, industry uses large quantities of water - often of drinking water quality - mainly for cooling processes, which are lacking in supply, especially during dry periods. In addition, the polluter pays principle will apply to wastewater disposal in future. As a result, resources currently used that have a negative impact on water quality may only be used in future subject to strict conditions and additional costs or may no longer be used at all.

Are there also approaches for a circular water economy?

L. Havighorst: Yes, there are indeed. As the contamination content in the wastewater is almost completely avoided by our treatment method, new uses for the effluent from cooling systems are emerging for the first time. Wastewater can be returned to the natural water cycle. One of our reference customers is allowed to feed the cooling water discharge into the company's own fire-fighting pond after receiving approval from the authorities. This not only saves wastewater costs, but the water is also used to irrigate green spaces and can have a positive effect on the groundwater table. The possibility of a circular economy therefore exists.

How do these benefits for customers affect the EU taxonomy and the CSRD criteria?

L. Havighorst: Through the effects described, we generate a very positive contribution for the sustainability reporting of companies in several subject areas, including the EU taxonomy Article 9 with five of the six goals. Our revolutionary approach positively supports six UN SDG goals, the CSRD guidelines and the ESRS criteria - E3-4 Water Management Performance. The impact of our products is therefore unusually broad.

What does a change of treatment look like for the customer and what advantages does the change bring?

L. Havighorst: Our customers, particularly in the chemical industry, are under great cost pressure, especially due to the energy price issue. Our contribution here is positive. Switching to the new treatment method is possible without any additional expense. Cost benefits are realized after just a few months, and projects show a positive ROI after just one year.


About The Author

Lars Havighorst is the founder and CEO of Blue Activity and is responsible for business development, partner management, finance, and marketing. He completed his BBA at Karlsruhe University of Applied Sciences, specializing in finance and sales. After his studies, he initially worked in financial consulting for more than 13 years before he began to focus intensively on the topic of water in the industry in 2018 and finally founded Blue Activity together with his co-founder Michael Simon at the beginning of 2021.



CM   Business Idea


Not just new, but revolutionarily different

Using biocides for the hygienic operation of industrial evaporative cooling systems was yesterday. Blue Activity revolutionizes this way of thinking by successfully replacing environmentally hazardous biocides with 100% functional microorganisms of natural origin. Combined with an easy-to-implement 360° service offering for the safe and long-term sustainable operation of industrial evaporative cooling systems. Companies can therefore quickly, safely, and easily switch their water treatment to the use of natural microorganisms and benefit from cost advantages.

When the customer commissions Blue Activity, it takes over the complete water treatment of the selected systems. Together with its customers, the start-up converts the water treatment to the use of microorganisms within a maximum of three days and offers customers modern 24/7 online monitoring (Remote Monitoring & Diagnostic) for improved system support, so that all relevant KPIs can be called up at any time via remote maintenance and the values can be continuously analyzed and adjusted. This means that the necessary service visits can be conducted as required and therefore in a cost-optimized manner.

To enable customers to meet the more stringent future water and wastewater regulations of the ESRS criteria in the best possible way, Blue Activity not only provides a natural substitute for biocides, but also offers biopolymers made from the waste of renewable raw materials for hardness stabilization treatment. For efficient corrosion protection, the phosphate content in the product has been reduced to a fifth, which significantly improves the wastewater limit values. Blue Activity can therefore supply everything from a single source to ensure the sustainable and safe operation of open recooling systems.


Blue Activity GmbH, Heidelberg



CM   Elevator Pitch


Milestones and Roadmap

Blue Activity is a CleanWaterTech start-up founded in 2021 for industrial water treatment with natural microorganisms instead of biocides. As an innovative solution provider for the water treatment of industrial evaporative cooling systems, the company offers its customers an all-round carefree package with natural operating materials for budget-optimized operation of these systems and focuses on the best possible symbiosis of innovation, sustainability, and cost efficiency in its range of solutions.

By consistently replacing biocides with natural microorganisms and substituting petroleum- and heavy metal-based polymers for corrosion protection and hardness stabilization with environmentally friendly biopolymers, hazardous substances can be safely avoided in accordance with ruling legislations of the Hazardous Substances Ordinance. This conserves water resources and improves wastewater quality in line with the National Water Strategy and the increasingly stringent regulations in this context.

In 2022, Blue Activity's first full financial year, around 250,000 m3 of make-up water and discharge (wastewater) were reduced annually together with customers, while at the same time saving around 68 tons of biocide, which led to further cost savings for customers. These values are to be increased annually by converting further systems in order to protect drinking water resources more sustainably.




  • Foundation of Blue Activity GmbH
  • Two reference customers acquired with pilot systems


  • Nominee at the Next Economy Award 2023, Düsseldorf
  • Another three well-known reference customers acquired with pilot systems
  • Support from five business angels


Entry of a seed investor

  • Registration of two patents
  • Another four systems acquired
  • Finalist at the Tech Tour "Water Tech 2023", Aarhus (Denmark)
  • 2nd place at the Econic Start-Up Award 2023, Frankfurt
  • Nominee Best of Industry Award 2023, Würzburg
  • Nominee Next Economy Award 2024, Düsseldorf
  • Selected Circular Economy Accelerator Program 2023, Wuppertal
  • Finalist Heidelberg Founder Award 2023, Heidelberg



  • Further development of in-house online monitoring incl. dashboard
  • Internationalization of the business
  • Expansion of strategic partnerships for better market cultivation
  • Expansion of the product range (wastewater treatment plants, process water, etc.)




We would like to thank the sponsors of the CHEManager Innovation Pitch for making this publication possible!

BioCampus Straubing Sponsor CHEManager Innovation Pitch



    Ruhr-IP Sponsor CHEManager Innovation Pitch  

Siemens Sponsor CHEManager Innovation Pitch




BlueActivity GmbH

Rudolf-Diesel-Str. 11
69115 Heidelberg

+49 6221 - 6484077