A solar-powered system designed to remove excess water from these residues

Company and project background

Alhomna Systems is a French cleantech startup developing solar technologies designed to transform organic residues into valuable resources. Our vision is to demonstrate that environmental solutions can also be economically viable. We believe that sustainable technologies, inspired by low-tech principles, can become profitable when they focus on transforming and valorising existing material flows.

Many organic residues produced by wastewater treatment plants, agriculture or the food industry still contain valuable nutrients and organic matter. In theory, these materials could replace part of the chemical fertilizers used today. However, in practice they are difficult to manage because they contain a large amount of water and must be stored during periods when land spreading is not allowed.

Through the Up2Circ programme, we explored the feasibility of SolarDry, a solar-powered system designed to remove excess water from these residues. By concentrating the material and making it more stable, SolarDry reduces transport volumes and facilitates storage and handling.

This approach helps create the conditions for better valorisation of organic matter while also improving the social acceptability of residue management by reducing odours, transport, and operational constraints.

What motivated you to make your business more circular?

The motivation came from observing how inefficient the current system can be when managing organic residues.

In many cases, sludge and digestates are transported over long distances even though most of their weight is simply water. This creates high logistics costs, unnecessary energy use, and additional CO₂ emissions.

At the same time, these materials still contain nutrients and organic matter that could be reused instead of being treated purely as waste. We saw an opportunity to rethink this process by combining solar energy and circular resource recovery.

The SolarDry project was therefore initiated to explore how solar heat could reduce volumes, lower environmental impacts, and support more circular management of organic residues.

Implementation Process

What were the main objectives of your feasibility study?

The objective of the study was to evaluate whether a solar-powered dehydration system could realistically work for treating sludge and organic residues.

We wanted to understand the technical feasibility of using solar heat to evaporate water, the environmental benefits of reducing transport and fossil energy use, and the potential economic value for operators.

Several indicators were analysed, including dry matter increase, reduction of transported volumes, energy substitution, and potential emission reductions.By combining technical modelling with market and logistics analysis, the study aimed to determine whether SolarDry could become a practical circular solution for waste management.

What activities did you carry out as part of your project?

The project involved a combination of technical analysis, data modelling, and market exploration.

We first conducted engineering modelling to understand how heat would circulate inside the SolarDry reactor and how efficiently water could be evaporated using solar thermal energy.

We also analysed solar irradiation data and compared it with the geographical distribution of wastewater treatment plants and agro-industrial sites. This helped identify territories where solar drying could be particularly relevant.

Finally, we analysed logistics and economic factors such as transport distances, energy prices, and potential uses for the dried material.

What feedback did you receive from stakeholders (customers, suppliers etc.)?

We exchanged with wastewater operators, agro-industrial companies, and experts in waste management to better understand their operational constraints.

Many stakeholders confirmed that reducing the volume of wet residues is a major challenge today, both economically and environmentally. Transport costs, regulatory pressure, and energy prices are all increasing.

They also highlighted the importance of solutions that can be implemented directly on site, without requiring heavy infrastructure.

This feedback helped us refine the project and identify promising early applications, particularly in agro-industrial contexts where moderate but continuous residue flows are common.

Impact & Outcomes

What are the main results and outcomes of the project for your company?

The feasibility study confirmed that solar-powered drying could significantly reduce the volume of wet residues.

By increasing the dry matter content to around 60%, the transported mass can be reduced by approximately two thirds. This means fewer truck movements, lower logistics costs, and reduced environmental impacts.

The study also confirmed that solar thermal energy can substitute part of the fossil energy typically used in conventional drying systems.

Did you detect a positive impact of circular transition for your company and for the environment?

Reducing the water content of sludge and organic residues directly reduces transport-related emissions and energy consumption. At the same time, replacing fossil energy with solar heat improves the overall environmental performance of the process.

Another important aspect is that dehydrated organic matter becomes easier to handle and can potentially be reused as a resource, for example in agriculture or as a biomass material. In this way, the project contributes both to renewable energy use and to the circular management of organic resources.

Which changes have you already implemented?

The study helped us refine the SolarDry concept and better understand the most promising use cases. Based on the results, we are now preparing the next development phase, which will involve building and testing a pilot system in real industrial conditions.

This pilot will allow us to collect operational data, validate the performance of the technology, and prepare the path toward future deployment.

Lessons learned

What key lessons did you learn regarding circular innovation?

Technological innovation alone is not enough. It is essential to understand how solutions will be used in practice and how they fit into existing industrial processes.Working closely with stakeholders helped us better identify practical needs and opportunities.

Did you encounter any challenges?

The main challenge was identifying the right first markets for deployment. Different sectors have different operational constraints, so finding the best early adopters is an important step.

If you could do your project again, what would you do differently?

If we started the project again, we would involve industrial stakeholders even earlier in the feasibility phase. Early discussions with potential users help identify operational constraints and accelerate the transition from concept to real-world implementation.

Future plans & recommendations

What are your next steps towards circular transition?

Our next step is to build and test a pilot version of the SolarDry technology in real industrial conditions. This will allow us to validate the concept at a larger scale and demonstrate how solar-powered drying can support circular waste management.

Is there any advice you would give to other SMEs looking to implement a circular project?

Start with a clear problem that needs solving and talk to potential users early. Circular innovation often emerges from practical challenges, and collaboration with stakeholders helps ensure that new solutions create real value.

How can policymakers or financial institutions better support businesses in adopting circular practices?

Programmes like Up2Circ are extremely valuable because they allow SMEs to explore innovative ideas and validate concepts before making large investments. Additional support for pilot projects and demonstration facilities would help accelerate the transition from feasibility studies to real industrial deployment.

Do you have any additional comments or reflections about your participation in the Up2Circ project?

Participating in the Up2Circ programme was a valuable first experience with European funding and reporting processes for our company. While these programmes involve a structured and formal framework, Up2Circ provided an accessible entry point that allowed us to better understand how European innovation funding works.

It was therefore a very useful first step for us. Beyond the technical work carried out during the project, it helped us gain experience with European project management and opened new perspectives for future programmes such as LIFE or Interreg.