A revolution in sludge treatment

A paradigm shift

Polymer free dewatering and drying

Energy efficient


A paradigm shift in sludge treatment

A paradigm shift in sludge treatment

Let us present a new tochnology where we by freezing, thawing and drying, dewaters and dries sludge to get a cleaner water and a valuable final product. Completely without the addition of polymers and with minimal energy use.



By far, the most flexible sludge treatment process

The Freeze Dry Unit can treat almost every type of sludge. Freeze Dry Unit can treat sludge regardless if it comes from a wastewater treatment plant, paper pulp or food industry. Freeze Dry Unit dewaters and dries the sludge to a dryness of 95 percent or the degree of dryness desired by the custumer.

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The Freeze Dry Unit leaves a small environmental footprint on the earth

By using a method, unlike the competitors, that doesn't requre the addition of polymers to dewater the sludge the final product can safely be used as fertilizer on farmland and form a circular economy of phosphorus. Freeze Dry Unit also reduces energy consumption and lowers transports.

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Minimal stake, low operational costs and long lifespan

The Freeze Dry Unit allow users to save money regarding energy, operation and transportation costs. In addition, the Freeze Dry Unit gives a valuable resource as a final product.

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Voices about Freeze dry unit

”We have delivered facilities, systems and processes for clean water in more than 70 countries. We see many interesting values with Freeze Dry Unit. Both that it reduces the energy use and that it doesn’t require any polymers or chemicals. This could be an economic and technical solution that strikes internationally. Freeze Dry Unit takes a step closer a circular solution for sludge treatment.”


Market Director, Purac

”We are proud to be one of the first to try Freeze Dry Unit. The results speak for themselves. With Freeze Dry Unit we got a sludge with a dry solids content of 95 percent - from a sludge free from polymers and a dry solids content of only two percent. And this, without the addition of polymers or chemicals in the process! The results means fewer transports and a sludge we can reuse. We really recommend others to try Freeze Dry Unit and discover the advantages.”


Operations Manager, VA Oxelö Energi AB

"At Isle, we love to see innovative solutions to major water sector challenges. Elajo's FreezeDry certainly fits the bill; it is a fundamentally different approach that could make sludge treatment significantly more sustainable. We hope the technology meets expectations in large-scale trials and look forward to helping Elajo engage with wastewater companies around the world."


Head of Dealflow

Network meeting in Stockholm


December 17th we will present Freeze Dry Unit at a network meet in Stockholm

Successful launch at Aquatech!


Freeze Dry Unit was met by many stakeholders in Amsterdam

Presentation at TAG-meeting in London!


Freeze Dry Unit is presented at Isle Utilities TAG-meeting in London the 21st of November!

Visit us at Aquatech!


We will be at Aquatech in Amsterdam, one of Europes biggest exhibitions for water and wastewater, and present the Freeze Dry Unit to the market for the first time

Questions and answers about Freeze dry unit

Why does the Freeze Dry Unit not need any polymers to work?

Polymers are used to floch the sludge and help the dewatering process in tradiotional mechanical dewatering methods, such as a centrifuge or screw press. No polymer are needed as the freezing process in he Freeze Dry Unit separates sludge particles and water.

How can the final product be utilized?

After the sludge is dried it can be used in an incineration chamber, as fertilizer on farmlands or other ways of disposal. Because the Freeze Dry Unit doesn’t require any polymers or other additives the final product is very suited as a fertilizer, provided that the sludge itself is not toxic.

What happens to the process reject water?

Reject water could be fed to a water treatment process at the wate water treatment plant, or be collected to be used as ferilizers, if enough nutients are present.

Why do you want to achieve a high dry solid content?

A higher dryness of the sludge opens up more ways of dispsal. For example sludge with a high enough dryness can be incinerated and phosphorus can be mined from the ashes as well as he incineration releases energy that can be used.

A high dryness also reduces the amount of transports needed as there is less water in the sludge. The transports can be reduced by as much as 80 %. This is good for the environment.

Why should nutrints in the sludge be recycled?

Nutrients like phosphorus and nitrogen are vital to the agriculture as they are needed to grow crops. Phosphorus is mined from the ground but deposits have decreased and mining has gotten more expensive. There is also a big evironmental impact when mining phosphorus and with the production of inorganic fertilizers. If nutrients can be recycled, mainly phosphorus, a big part of the phosphorus in sewage sludge could replace phosphorus that in other case would be mined.

What happens to other substances in the sludge?

Nutrients in the sludge are mostly nitrogen and phosphorus. Most of the phosphorus are bound to the sludge and will end up in the sludge after the process. Nitrogen is more present in the water and will therefore end up both in the sludge and in the process reject water, but mostly in the sludge.

Thera are also often heavy metals in sludge. These are bound to the sludge particles and stays in the sludge after the dewatering and drying process.

How much energy is needed?

If the sludge fed into the Freeze Dry Unit has a DS of 2 % the needed energy is 20-50 kWh depending on sludge type. This equals to 2,5 kWh/kg DS.

Is it a batch process or a continuous?

It is a continuous prcess.

Can hygienization be achieved?

It is possible to add a step of hygienization where the sludge is helt above 70 degrees Celsius for a minimum of one hour.

Is there bad smell from the process or the final product?


What volumes can be treated?

Freeze Dry Unit is fully scalable and is not restricted by volume.