Three decades of Innovation: An interview with the CTO on Cambi’s 30th anniversary

This 2022, Cambi celebrates three decades in the sludge and organics treatment industry. Cambi's Chief Technological Officer, Hans Rasmus Holte, recently spoke on the rich history and evolution of Cambi's thermal hydrolysis technology at a webinar for the Americas. He was one of the few who were there in the company's early days as a start-up in Norway. In this short interview, we ask the CTO what he believes has brought the company to where it is today and the inroads that will lead Cambi to an even brighter tomorrow.

You have been part of almost the entire journey of Cambi. What do you believe success factors have led Cambi this far in such a challenging field?

Ultimately, it is a combination of the fit between the market need and the technology we offered, the risks we took and the integrity with which we made and developed the technology, and the belief in the product despite the long time it took to develop the market and the lead times within the municipal wastewater sector.

As a start-up back then, Cambi became aware of the trends early and thoroughly developed a hypothesis- and it was that the company would have long-term advantages by addressing specific challenges within the wastewater industry. I think it's because we took the right opportunities and kept ourselves focused, knowing how valuable our ideas were. We developed, qualified, and justified forward-looking solutions and said no when distractions appeared, although we have also learned from errors. Focusing on sustainable improvement and becoming really good within a core business area and avoiding disadvantageous pathways were important.

Then and today, many new tech companies with promising technology have a high burn rate early in the game, not being mature and ready to widely market a product to prepare the market, but Cambi took the right and necessary risks, and landed a first client that fortunately took a chance on us fast. That was the plant in Hamar, Norway, and its reliable operation opened doors for us down the road. Similarly, early adopters such as Mjøsanlegget, Thames Water, and DC Water have been important door-openers in new markets for Cambi. In this industry specifically, it also helped that we had long-term investors early on who, at the very beginning, understood the business and the returns.

A solid strategy based on enduring drivers cannot be stressed well enough, either. We steadily grew the business and expanded to other countries, studied and covered all the bases- legislative and design requirements, different sludge characteristics across various plants – we strengthened our technical capabilities well. We had a strong theoretical foundation for developing the technology, and we had loyalty to data. Collecting and processing that data for decision-making is key in technology evolution. Cambi has always had a bedrock rooted in scientifically proven concepts and continues to improve our processes systematically. Today, our capability of handling "big data" accelerates our innovation.

Lastly, I really believe having a multidisciplinary highly-skilled team was a crucial factor. Cambi took in people with different backgrounds who were willing to challenge one another, strengthen one another, and this created an environment that made the technical goals achievable. This is still the case within Cambi today, and a strong advantage I believe should be of strategic importance for most tech companies who want to succeed in our industry. This comes in addition to working closely together with the client to address and solve their specific challenges.

What's a valuable yet difficult learning you've had in the process? Any challenges that had an impact on today's process and products?

Secondly, and this is more of the technical growth aspect, is the streamlining of the thermal hydrolysis process plant that we offer to the public. One part of this is learning that we needed to move to the batch-process thermal hydrolysis system from the continuous system, which suffered from scaling, erosion, and other issues.

Another important part of our technical evolution, which happened over several years, was the shift from project design to product design. Every client plant is different, and in the past, we designed systems specifically to fit these plants, which at the time was beneficial because it meant we were very flexible, and it helped us learn a lot about client preferences. This customisation strategy, however, opens us up to a long lead time and even errors when we allow too much flexibility. We began to standardise our product as a result. We knew which components work best together considering different client needs, different sludge varieties, climate; we had years of experience with monitoring, testing, and the systematical registration of non-conformities; we learned how to maintain a bit of flexibility with components in various countries without adding risk – all that lead to the robust portfolio we have today. We have also worked closely with sub-suppliers to further develop and improve components where common industry standards did not suffice. There was difficulty in becoming conservative in that respect, but ultimately, it led to highly reliable systems with high uptime and availability.

Today we even have Cambi PLUS, which allows us to monitor THP plants in real-time, and this has only allowed us to accelerate the development of the technology further.

What is your perception of the market's understanding of the thermal hydrolysis process today? Are there misconceptions or opportunities you wish to tackle soon?

In general, I think the awareness and understanding of thermal hydrolysis among industry players and consulting bodies are commendable. Of course, it's not uncommon to encounter utilities today that still think that increasing digester volume is the only way to deal with increasing sludge quantities, but with thorough research and evaluations of sludge treatment systems as a whole, thermal hydrolysis becomes a clear option for many plants, reducing not only investment in digester volume to about 1/3, but often, more importantly, reducing annual opex. The mindset of tackling the energy and mass balance of the entire sludge treatment system and not just thinking of parts individually can greatly help utilities save on costs and significantly improve carbon footprint.

What to you is the most exciting thing you foresee for thermal hydrolysis in the coming decades?

I can't lay out all the cards in this interview, but there are a few things we openly talk about and share in terms of innovation for thermal hydrolysis.

Firstly, we are making headway in showing the versatility of THP when it comes to configurations. In most installations around the world, the thermal hydrolysis process goes before anaerobic digestion where all sludge is treated, but other schemes have varying benefits that can suit the needs of other plants. For example, THP can be used after digestion prior to final dewatering in sites with ample digestion capacity. This results in the most significant biosolids volume reduction among the configurations and will still result in higher biogas production as the centrate can be recirculated to the digesters. Extensive scientific work has been done on a large range of anaerobically digested biosolids, and this method is well documented. Cambi has demonstrated this technology in full-scale in Germany in Europe, and such a configuration is now scheduled to be delivered to the Deurne-Schijnpoort sludge treatment plant in Belgium by 2023.

When it comes to digital technology, we are incessantly improving on our remote monitoring system called Cambi PLUS. Clients who want the added benefit of this modular digital platform can upload test parameter results where they would otherwise be automatically calculated, giving more accurate views of the system, and then consult with our engineers for optimisation advice. This allows Cambi not just to glean useful information from our plants in real-time but also to reduce the time spent on on-site process monitoring and optimisation as well as maintenance tasks.

We are also testing the technology with different types of feedstocks, including sludge from the pulp and paper industry. We have a demo plant now installed at the Secunda plant of Sasol, a chemicals and energy company in South Africa, and we are further expanding the horizon of our technology. It will be tried on the plant's industrial sludge coming from their gasification process to see if it can be refed into the system and therefore reduce waste.

Another growth space for us is co-digestion – the use of anaerobic digestion on two types of feedstocks, typically sludge with food waste or some other type of organic waste stream, like Fats, Oil, and Grease (FOG). This holds considerable potential for municipalities to not just increase biogas production but reduce methane and CO2 emissions. Cambi, to date, already has seven co-digestion references in countries where the practice is common such as Norway, Sweden, Korea, and China.

Any memorable moment in Cambi's history you'd like to share?

Some key achievements and contracts, of course, have made me very proud in these last 30 years. For example, how the technical team designed the technology to handle high-viscosity sludge, so that we can operate at higher dry solids, and how we recently innovated to recover more heat and reduce the steam consumption up to 30%. As a person who is very motivated by problem-solving and improving industry practice, these were such gratifying milestones in my career.

I also remember the first biowaste plant we had in Lillehammer. That was monumental in that we were applying thermal hydrolysis to a completely different waste stream and making a difference.

If I had to say, however, what the thing I treasure most is in this last three decades, it would have to be how thorough we work in such a diverse environment. I love working in a team, and knowing the breadth of interdisciplinary expertise and experience surrounding me will find the solution to any problem through thorough effort. It's an amazing feeling seeing our predictions and solutions be so spot-on because of that accumulated collective knowledge. I remain humbled and have great respect when approaching the unknown or venturing into new areas, but it's for this reason that I'm not afraid of encountering difficulties and challenges in my work for Cambi. I know our teamwork, our humility, and our commitment to hard work.

An achievement that makes me proud when looking at the past 30 years of development is how we have actually managed to realise our ambitions and contribute so much to developing technology that advances the circular economy.

We're fit and ready to just keep evolving, keep growing.

31 January 2022


Hans Rasmus Holte

Hans Rasmus Holte has been with the company for more than 25 years and holds several patents in Cambi's portfolio. His past contributions and pending patents are crucial in maintaining Cambi’s position in advancing the circular economy and a carbon-neutral future.

Mr. Holte has been pivotal in the development of the thermal hydrolysis process technology and its full-scale applications at wastewater treatment plants. He has been involved in research and development; process modelling, design, and troubleshooting; product management and standardisation; and project management and project development both within the municipal and industrial sector He has broad experience with biosolids, biowaste, waste processing systems, and biofuel utilisation.

He has a degree equivalent to an MSc in Forestry from the Norwegian University of Life Sciences (1993), where he started his career as a research officer.  

Hans Rasmus Holte at Cambi Group AS
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